SwePub - sökning: WFRF:(Uz Zaman Ashraf 1975)

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1.	Glazunov, Andres Alayon, 1969, et al. (författare) Capacity Gains of (3 × 3)×(3 × 3) MIMO Fixed Links with Planar Aperiodic Sparse Arrays in Pure-LOS Channels 2018 Ingår i: Proceedings of the 2018 8th IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications, APWC 2018. ; , s. 734-736 Konferensbidrag (refereegranskat)abstract © 2018 IEEE. Presented is an analysis of the topology of a 3 × 3 element planar (square) array antenna with vertically polarized isotropic antenna elements. The focus has been on fixed multiple-input multiple-output communication links in pure line-of-sight channels. An empirical equation is presented for the mid-elements' relative position on the sides of the square array achieving near-optimal (3 × 3) × (3 × 3) multiple-input multiple-output capacity. It is observed that the position is a function of both the separation distance between transmit and receive antennas and the wavelength of the transmit signal in a similar way as for 3 × 3 systems with linear arrays. The capacity gains of the aperiodic planar array over the uniform planar array antenna configurations are presented. It is shown that considerable capacity gains in capacity can be obtained by choosing the right array topology following a simple design rule.
2.	Maaskant, Rob, 1978, et al. (författare) Spatial Power Combining and Splitting in Gap Waveguide Technology 2016 Ingår i: IEEE Microwave and Wireless Components Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-1764 .- 1531-1309. ; 26:7, s. 472-474 Tidskriftsartikel (refereegranskat)abstract A single-layer spatial power splitter-combiner structure is packaged in gap waveguide technology. The measured metal-only back-to-back structure features an average insertion loss less than 2.3 dB and a return loss larger than 10 to 20 dB over the entire 75-110 GHz W-band. The design procedure is outlined and the measured and simulated results are shown to be in good agreement. The structure can be used as a stand-alone power splitter and/or combiner (single-mode, all-excited in-phase channels), a quasi-optical beamformer to excite an array of slot antennas in the top ground plane by ridge gap waveguides, or as a back-to-back RF component in grid amplifier designs.
3.	Pivnenko, Sergiy, et al. (författare) Using a Conical Horn as Compact Antenna Test Range Feed in Millimetre Bands 2022 Ingår i: 2022 16th European Conference on Antennas and Propagation, EuCAP 2022. Konferensbidrag (refereegranskat)abstract Using a conical horn as a feed for a single offset-fed Compact Antenna Test Range (CATR) is described. Although such horn has larger variation of the phase centre with frequency and slightly different beamwidth in the E-plane and H-plane within the used field of view, as compared to a specially designed corrugated horn feed, good results were obtained for the measured amplitude and phase variations in the Quiet Zone at mm-band. Some details of application of conventional conical horns as CATR feeds are also explained.
4.	Shah, Waqar Ali, 1987, et al. (författare) W-band spatial power combiner and splitter in gap waveguide technology 2016 Ingår i: 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016, Fajardo, Puerto Rico, 26 June - 1 July 2016. - 1522-3965. ; , s. 255-256 Konferensbidrag (refereegranskat)abstract A passive power splitter and combiner has been designed in-between two metallic ground plates using gap waveguide technology. The measured insertion loss is smaller than 2.3 dB and the return loss is larger than 10 dB over the entire W-band (75-110 GHz). The design procedure has been detailed and the simulated and measured results for the proposed structure are shown. The designed structure can be used as a passive power splitter or combiner, as a grid amplifier in a back-to-back RF chain, or as a quasi-optical beamforming component in beam steering antenna arrays.
5.	Svensson, Arne, 1955, et al. (författare) In memory of Professor Per-Simon Kildal 2016 Ingår i: IEEE Antennas and Propagation Magazine. - 1045-9243. ; 58:4, s. 116-117 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
6.	Uz Zaman, Ashraf, 1975, et al. (författare) 3D Printed Periodic Structures for RF Packaging of Integrated Array Module at sub-6GHz Band 2021 Ingår i: 2021 International Symposium on Antennas and Propagation, ISAP 2021. Konferensbidrag (refereegranskat)abstract Wideband PMC packaging solution fabricated by low cost 3D printing technology has been proposed as an alternative to conventional metal wall solution for isolating critical active circuits in integrated arrays operating at sub-6GHz. The two proposed periodic structures named as triangular pins and conical pins produce a parallel-plate stopband over the frequency range from 2.5-6GHz and 2.1-5.5GHz respectively. A test structure, containing passive microstrip lines placed on a FR4 substrate, has been used to verify the packaging performance of the proposed 3D printed structures and the measured isolation performance of the newly proposed periodic structures agree very well with the simulated performance. Isolation level better than 40-50dB has been demonstrated within the band of interest.
7.	Albadalejo Lijarcio, Juan Luis, 1994, et al. (författare) Low-cost Coaxial Slot Array Antenna for E-band Automotive Corner Radar Applications Based on Gap Waveguide MLW Technology 2024 Ingår i: 18th European Conference on Antennas and Propagation, EuCAP 2024. Konferensbidrag (refereegranskat)abstract This paper presents an E-band automotive radar antenna based on multilayer waveguide (MLW) technology. The electromagnetic fields propagate through a low-loss air-filled coaxial transmission line created by the stacking of three separate metal sheets. The fundamental antenna element consists of a single side-fed column composed of six in-line slots. An electromagnetic bandgap (EBG) structure is integrated along the transmission lines to mitigate the unwanted leakage resulting from small air gaps between the metal sheets. The fabrication of the prototype was realized by using a quick and cost-effective sheet metal manufacturing process, which has proven to be highly suitable for large-scale production. The measurement results for both radiation pattern and reflection coefficient agree with the corresponding simulations within the operating frequency band ranging from 76 to 81 GHz. The measurements results demonstrate a return loss better than 10 dB across the designated frequency band and the realized gain of the antenna is, on average, 11.5 dBi, with a beam width of 120 degrees in azimuth (E-plane) and 20 degrees in elevation (H-Plane).
8.	Albadalejo Lijarcio, Juan Luis, 1994, et al. (författare) Substrate-Less Vertical Chip-to-Waveguide Transition for W-Band Array Antenna Integration 2023 Ingår i: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP. - 2164-3342. - 9788831299077 Konferensbidrag (refereegranskat)abstract This paper presents a vertical transition from a high permittivity GaAs MMIC to rectangular waveguide using bondwires as a coupling structure. The transition is advantageous for the direct integration of any off-the-shelf chip into a waveguide antenna since no modification of the GSG-pad or additional substrate is needed. An EBG structure consisting of pins is used for the packaging of the chip in order to avoid field propagation in undesired directions. The simulations results show that the reflection coefficient is lower than -10 dB and the average insertion loss is better than 0.5 dB from around 87 to 101 GHz (14% relative bandwidth).
9.	Alfonso Alos, Esperanza, 1979, et al. (författare) Gap waveguide components for millimeter-wave systems. Couplers, filters, antennas, MMIC packaging 2012 Ingår i: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest). - 1522-3965. - 9784885522703 ; , s. 243-246 Konferensbidrag (refereegranskat)abstract Design of passive components (couplers, filters and antennas) and MMIC packaging validation intended for RF front ends for microwave links at 38 GHz using gap waveguide technology have been shown. The use of this technology allows all-in-one integration of receiver, transmitter, and diplexer including the antenna into one mechanical unit. These initial designs and studies have been made at the microwave band for validation and measurement purposes, and for comparison with existing technology. They represent the first step towards the application of gap waveguides to millimeter-wave systems, where gap waveguides could have a large potential.
10.	Alfonso Alos, Esperanza, 1979, et al. (författare) Ka-Band Gap Waveguide Coupled-Resonator Filter for Radio Link Diplexer Application 2013 Ingår i: IEEE Transactions on Components, Packaging and Manufacturing Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 2156-3985 .- 2156-3950. ; 3:5, s. 870-879 Tidskriftsartikel (refereegranskat)abstract Gap waveguide technology represents an interesting alternative as low-loss, cost-effective, and high-performance transmission line and package of microwave and millimeter-wave systems. A Ka-band coupled-resonator filter for a radio link diplexer, which requires high selectivity to isolate transmit and receiving channels, is proposed and realized using gap waveguide technology. The band-pass filter, which has a central frequency of 37.37 GHz and a pass bandwidth of 560 MHz, is fabricated between two parallel metal plates, leaving an air gap between them. After milling one of the plates, silver-plating is applied on them. Measurements show a minimum in-band insertion loss of 1 dB and agree quite well with simulations.
11.	Algaba Brazalez, Astrid, 1983, et al. (författare) Design of a coplanar waveguide-to-ridge gap waveguide transition via capacitive coupling 2012 Ingår i: Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012. Prague, 26-30 March 2012. - 9781457709180 ; , s. 3524-3528 Konferensbidrag (refereegranskat)abstract A transition from Coplanar Waveguide (CPW) via capacitive coupling in order to provide feeding to the so-called Ridge Gap Waveguide (RGW) has been investigated. The main objective of this work is to find a way to facilitate integration of active electronics with the gap waveguide structure and also to do measurements of the components made in gap waveguide technology working around 100 GHz. The transition design and simulation of S parameters for the designed topology is presented.
12.	Algaba Brazalez, Astrid, 1983, et al. (författare) Improved Microstrip Filters Using PMC Packaging by Lid of Nails 2012 Ingår i: IEEE Transactions on Components, Packaging and Manufacturing Technology. - 2156-3985 .- 2156-3950. ; 2:7, s. 1075-1084 Tidskriftsartikel (refereegranskat)abstract This paper shows that microstrip filters perform like textbook examples when packaged with perfect magnetic conductor (PMC). A PMC is made as a pin surface or lid of nails, and this is used to package a microstrip parallel coupled line bandpass filter. Our measurements confirm that parallel plate, cavity modes, and radiation are suppressed. This paper also includes a study of the reasons for a frequency shift between the ideal PMC packaged case and the realized case.
13.	Algaba Brazalez, Astrid, 1983, et al. (författare) Improving microstrip filters with gap waveguide packaging 2011 Ingår i: Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011. Rome, 11-15 April 2011. - 9781457702501 ; , s. 1080-1084 Konferensbidrag (refereegranskat)abstract A study is presented of the performance of microstrip filters packaged with Perfect Magnetic Conductor (PMC) and realization of the PMC using a lid of nails. A 3rd order parallel coupled-line bandpass filter is designed and packaged with a lid of nails at the Ku-band. The study shows the PMC packaging technique is very efficient in improving the filter characteristics including the insertion loss in the bandpass region.
14.	Algaba Brazalez, Astrid, 1983, et al. (författare) Investigation of a Microstrip-to-Ridge Gap Waveguide transition by electromagnetic coupling 2012 Ingår i: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest). - 1522-3965. - 9781467304627 ; , s. 1-2 Konferensbidrag (refereegranskat)abstract A transition from Microstrip to Ridge Gap Waveguide (RGW) has been studied and numerically analyzed in terms of S parameters. The RGW technology shows potential to be used up to THz frequencies. Therefore, good transitions are needed in order to make possible the measurements of RGW components at frequencies above 100 GHz.
15.	Alibakhshikenari, Mohammad, et al. (författare) Dual-Polarized Highly Folded Bowtie Antenna with Slotted Self-Grounded Structure for Sub-6 GHz 5G Applications 2022 Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:4, s. 3028-3033 Tidskriftsartikel (refereegranskat)abstract In this paper, a novel dual-polarized highly-folded self-grounded Bowtie antenna that is excited through I-shaped slots is proposed for applications in sub-6GHz 5G multiple-input-multiple-output (MIMO) antenna systems. The antenna consists of two pairs of folded radiation petals whose base is embedded in a double layer of FR-4 substrate with a common ground-plane which is sandwiched between the two substrate layers. The ground-plane is defected with two I-shaped slots located under the radiation elements. Each pair of radiation elements are excited through a microstrip line on the top layer with RF signal that is 180° out of phase with respect to each other. The RF signal is coupled to the pair of feedlines on the top layer through the I-shaped slots from the two microstrip feedlines on the underside of the second substrate. The proposed feed mechanism gets rid of the otherwise bulky balun. The Bowtie antenna is a compact solution with dimensions of 32 32 33.8 mm3. Measured results have verified that the antenna operates over a frequency range of 3.1–5 GHz and exhibits an average gain and antenna efficiency in the vertical and horizontal polarizations of 7.5 dBi and 82.6%, respectively.
16.	Alibakhshikenari, Mohammad, et al. (författare) Wideband Sub-6 GHz Self-Grounded Bow-Tie Antenna with New Feeding Mechanism for 5G Communication Systems 2019 Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019. ; March 2019 Konferensbidrag (refereegranskat)abstract This paper presents a self-grounded directional Bow-Tie antenna with a novel feed structure for sub-6 GHz applications in 5G communication systems covering 3.35-4.4 GHz. The antenna consists of two petal shaped metal structures that are fed by a bend microstrip line with an out-of-phase excitation. The petals are anchored on a common ground-plane. The feed mechanism used to excite the petals is by EM coupling from a single open-circuited microstrip line implemented behind the ground-plane. The coupling of EM energy from the input microstrip line to the feed microstrip line is controlled via an I-shaped slot printed on the ground-plane. The proposed antenna offers good impedance matching across its operating frequency range with VSWR<2 and exhibits an average gain of 20 dBi for an 8×8 element antenna array.
17.	Aljarosha, Alhassan, 1982, et al. (författare) A Wideband Contactless and Bondwire-Free MMIC to Waveguide Transition 2017 Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 27:5, s. 437-439 Tidskriftsartikel (refereegranskat)abstract A contactless transition from a high-permittivity microstrip line (e_r=9.9) to an air-filled waveguide (WG) has been impedance-matched over a large simulated relative bandwidth of 38% (W-band, 75-110 GHz). The transition couples the EM fields directly from the MMIC's microstrip line via an SIW and an off-chip stub section to a ridge WG section. The novel structure is low loss and suits pick-and-place assembly techniques of mm-Wave MMICs inside metal WGs. The design process is detailed and manufacturing tolerances of the Alumina prototype PCB are discussed. The measured back-to-back structure retains an appreciable insertion loss smaller than 0.8 dB for a single transition and a fractional bandwidth of 28% (72-95~GHz) over which the return loss is greater than 10 dB.
18.	Aljarosha, Alhassan, 1982, et al. (författare) Mm-Wave contactless connection for MMIC integration in gap waveguides 2016 Ingår i: 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016, Fajardo, Puerto Rico, 26 June - 1 July 2016. - 1522-3965. ; , s. 253-254 Konferensbidrag (refereegranskat)abstract A contactless, broadband and low-loss microstrip-to-groove gap waveguide transition operating at W-band is presented. The principle of operation is based on transforming EM fields from the SIW to the ridge gap waveguide mode via electromagnetic coupling. This is advantageous, since the proposed solution avoids the use of metal contact between the SIW and one of the waveguide parts. Furthermore, metamaterial-based gap waveguide technology provides a resonance-free packaging solution.
19.	Auriacombe, Olivier, 1989, et al. (författare) Oil, water, and ice detection on road surfaces with a millimeter-wave radiometer 2020 Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 11533 Konferensbidrag (refereegranskat)abstract Passive radiometers are well-known instruments used in the characterization of soil, sea surfaces and remote sensing of the earth atmosphere with satellites or airplanes. The instrument described in this article is a dual-polarised superheterodyne radiometer operating around 93 GHz. It is placed on a structure to measure road surface conditions (ice, water or oil) in a laboratory-controlled environment. This radiometer measures the reflected and emitted radiations from the road surface (asphalt and concrete) and the background temperature, in two orthogonal polarizations (H and V). The difference in the dielectric properties of the ice, oil and water from dry road surface allows to distinguish them efficiently. This kind of technique can be used for road surface recognition in all weather conditions and does not require presence of daylight or other sources of illumination. In this paper, calibration procedures and radiometric characterisations of the radiometer are studied in order to select the best and simpler method to operate the radiometer. It was found that calibrating the radiometer with only one blackbody target or using a table of gain and system noise temperature is sufficiently accurate over a long time to be able to distinguish dry from ice or water covered surfaces. The laboratory results are showing a high difference in the brightness temperature between road surface covered with ice, water or oil and the dry road surface. No ambiguities between those conditions exist but potential limitations could rise, for example if the road surface roughness changes during a measurement. Those promising results validate the potential of using radiometer for road safety and the automotive industry. The presented laboratory measurements are the first step towards the implementation of the instrument into a moving vehicle for alerting drivers ahead of unforeseen dangers. Downloading of the abstract is permitted for personal use only.
20.	Auriacombe, Olivier, 1989, et al. (författare) Road Surface Characterization Using a Radiometer at 100 GHz 2020 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2020-November, s. 136-137 Konferensbidrag (refereegranskat)abstract A dual polarization super-heterodyne radiometer operating between 85 and 100 GHz has been developed and used for surface characterization. The instrument can detect changes from dry to icy road in many environmental conditions (night, fog, rain) by measuring the combination of reflected/transmitted radiation from the surface at two orthogonal polarizations. The difference in brightness temperature between those polarizations is an accurate tool to distinguish ice from dry road surfaces. Results from measurement of dry asphalt and ice layers on asphalt are presented in this paper.
21.	Bencivenni, Carlo, et al. (författare) 5G mmWave Beam Steering Antenna Development and Testing 2019 Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019. - 9788890701887 Konferensbidrag (refereegranskat)abstract mmWave frequencies offer unprecedented capacity but also new technical challenges. Current solutions typically adopt integrated PCB antennas, however they still face issues when it comes to coverage, power consumption and cost. Instead, we present a SG mmWave antenna platform demonstrating a different approach based on Gapwaves technology. The proposed design is an integrated all-metal multi-layer assembly, offering low-loss feeding, high-gain subarray, high-Q filters and exceptional thermal handling. To support these claims, active measurement of beam steering, EIRP and temperature are presented. Results from this small demonstration unit are very encouraging and show performance challenging that of much larger systems.
22.	Bencivenni, Carlo, 1986, et al. (författare) Towards Integrated Active Antennas for 5G mm-wave Applications at Gapwaves 2018 Ingår i: 2018 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting, APSURSI 2018 - Proceedings. ; , s. 415-416 Konferensbidrag (refereegranskat)abstract Recently, in preparation for the upcoming 5G systems, the telecom industry has been showing a great interest in high frequency active antennas. We present a brief overview of the innovative design solution developed at Gapwaves for mmwave digital beamforming applications, capable of addressing all the associated technical issues. We review the general antenna architecture and components and explain how gapwaves technology enables us to achieve high performance, highly integrated active antennas in a cost effective way.
23.	Chen, Lei, et al. (författare) A Method of Reducing Mutual Coupling for a Finite Array 2020 Ingår i: 14th European Conference on Antennas and Propagation, EuCAP 2020. - 9788831299008 Konferensbidrag (refereegranskat)abstract A method of reducing mutual coupling for a finite array with the characteristics of wideband and beam steering is presented in this paper. By adding an extra decoupling network, the mutual coupling can be efficiently suppressed for the antenna array. To verify the validity of the proposed method, a 1 x 8 millimeter-wave array antenna based on the gap waveguide technology is used in this work. The simulation results show that the active reflection coefficients are improved from 6.98 dB to -8.29dB, and the mutual coupling between adjacent elements is reduced to below -16.73 dB covering 20-33 GHz with the beam steering angle range of +/- 70 degrees.
24.	Chen, Lei, 1982, et al. (författare) A Method of Reducing Mutual Coupling Using an Extra Coupling Path 2019 Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019. Konferensbidrag (refereegranskat)abstract A method of reducing mutual coupling for a large-scale array with the wideband and beam steering characteristics is proposed in this work. An extra coupling path is intentionally introduced to reduce the mutual coupling among adjacent radiating elements. A millimeter wave array is used to verify the proposed method. The simulation results show that the mutual coupling between adjacent elements can be reduced to below -15 dB over the band of 19-39.5 GHz and this concept is viable even for the beam steering angle range of ±45°.
25.	Fan, Fangfang, 1981, et al. (författare) Bandwidth Investigation on Half-Height Pin in Ridge Gap Waveguide 2018 Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 66:1, s. 100-108 Tidskriftsartikel (refereegranskat)abstract Gap waveguide is a promising transmission structure, especially for millimeter-wave (mmW) and terahertz applications. It does not require conductive connection between the upper and the lower plates, which makes this technology gain advantages over conventional rectangular waveguides and substrate integrated waveguides in an mmW and terahertz regime. Different fabrication methods for gap waveguides should be employed for different frequency bands applied, such as molding, milling, die forming, electrical discharge machining, microelectromechanical systems, and 3-D printing. Therefore, different pin forms used in gap waveguides are required to match the applied fabrication methods. In this paper, a new pin form, the half-height-pin form, in gap waveguides is proposed for reducing the fabrication cost, and its stopband characteristics are investigated and compared with the previous full-height pins in gap waveguides at the V -band. A device of a double-ridged gap waveguide with two 90° bends for verifying the stopband characteristic analysis of the new pin form has been designed and manufactured. The measured data confirm our analysis and simulations.
26.	Fang, Mu, 1992, et al. (författare) 1-Dimensional Wide Scanning Gap Waveguide Based Slot Array Antenna using Decoupling Technique for 100 GHz Applications 2024 Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 72:4, s. 3438-3450 Tidskriftsartikel (refereegranskat)abstract This paper presents a 1-dimenional wide scanning slot array antenna based on ridge gap waveguide (RGW), operating at a 100 GHz band. A novel half wall decoupling structure is proposed to reduce the mutual coupling and the reflection coefficient simultaneously, thus achieving a more stable active reflection coefficient (ARC) within the ±60° scanning range. At the same time, special attention has been given in retaining the embedded pattern suitable for wide scanning performance. An 8-element slot array antenna (8×8 slots) with two different feeding networks is fabricated and measured to verify the scanning performance. The prototype achieves 91% total efficiency while scanned up to 60° with 3 dB scanning loss. The measured results show good agreement with the simulations both for the reflection coefficient and radiation performance.
27.	Fang, Mu, 1992, et al. (författare) A Comparative Study of Decoupling Techniques for Waveguide Slot Array Antennas 2024 Ingår i: 18th European Conference on Antennas and Propagation, EuCAP 2024. Konferensbidrag (refereegranskat)abstract In this paper, we present a comparative study of three decoupling techniques for waveguide slot array antennas, including half wall, corrugation and metal fence. Their decoupling efficacy and impact on element patterns are investigated under two typical element spacings: 0.5λ0 and 1λ0. A summary highlighting the differences among these three decoupling techniques is provided to gain insight into which specific application scenarios are best suited for each technique.
28.	Fang, Mu, 1992, et al. (författare) Design of a Gap Waveguide Based Unit Cell for 1-D Beam Scanning Application at W-band 2023 Ingår i: 17th European Conference on Antennas and Propagation, EuCAP 2023. Konferensbidrag (refereegranskat)abstract In this paper, we present a 1-D scanning slot array unit cell column based on ridge gap waveguide technology which can be a good candidate for wide scanning antenna applications at 100GHz. A parametric analysis of the proposed model is organized to demonstrate the merits and potential performance. Simulated data in terms of H-plane pattern and impedance bandwidth as well as the scanning characteristics has been investigated for the unit cell column of slot array. Also, design concerns regarding manufacturing issues and corresponding mechanical challenges have been taken into account while doing the electromagnetic design. The chosen unit cell which consists of a column of slot array works with 6-16% impedance bandwidth and achieves a scanning up to ± 60° in one dimension.
29.	Farahbakhsh, A., et al. (författare) 60-GHz Groove Gap Waveguide Based Wideband H-Plane Power Dividers and Transitions: For Use in High-Gain Slot Array Antenna 2017 Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 65:11, s. 4111-4121 Tidskriftsartikel (refereegranskat)abstract Wideband design of power dividers, T-junctions, and transitions based on groove gap waveguide (GGW) technology is presented in this paper with the goal to use these components in high-gain millimeter-wave antenna array design at 60-GHz frequency range. Since this GGW technology does not require electrical contact between the different metal layers of a complex 3-D waveguide structure, the fabrication cost and mechanical complexity are decreased. The designed T-junctions and different power dividers exhibit wide operational bandwidth and low output power and phase imbalance over the 60-GHz frequency band. Also, two transitions from GGW to a standard rectangular waveguide have been designed. To validate the performance of the designed components, a 64-way power divider in combination with 256 radiating slots is designed, prototyped, and measured at 60-GHz band. Measurement results agree well with the simulated performance of the complete array antenna, and the antenna gain is more than 32.5 dBi. The total radiation efficiency is more than 80% over the operating frequency range from 57 to 67 GHz. Also, the measured sidelobe levels are found to be agreeing well with the simulated level.
30.	Farahbakhsh, Ali, 1984, et al. (författare) A mmWave Wideband Slot Array Antenna Based on Ridge Gap Waveguide With 30% Bandwidth 2018 Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 66:2, s. 1008-1013 Tidskriftsartikel (refereegranskat)abstract A wideband 8 x 8 element slot antenna array based on ridge gap waveguide feeding network has been proposed for mmWave applications. The antenna subarray consists of four radiating slots which are excited by a groove gap cavity layer. Compared with previously published works, the proposed planar antenna array has quite wide impedance bandwidth. The antenna covers a wideband of 50-67.8 GHz with 30% impedance bandwidth (VSWR < 2). Also, the antenna has only 2.5 dB gain variation over the entire bandwidth which implies also good radiation characteristics for the proposed antenna. The maximum measured gain value is about 27.5 dBi with a total efficiency of 80% for the proposed antenna within the band of interest. With this performance, the proposed antenna array is a promising candidate for mmWave communication systems.
31.	Farahbakhsh, A., et al. (författare) A Single Layer Dual-Polarization Array Antenna Based on Parallel Plate Gap Waveguide 2022 Ingår i: 2022 16th European Conference on Antennas and Propagation, EuCAP 2022. Konferensbidrag (refereegranskat)abstract A dual-polarization array antenna based on over-moded parallel plate gap waveguide is presented in this paper. The antenna has only one metal waveguide layer that leads to simplification of manufacturing process. The antenna sub-array has four patches that are excited by a parallel plate gap waveguide through a cross slot. Two reflectors are utilized to feed the parallel plate gap waveguides in two directions. The simulated results show that the antenna bandwidth is 8.8% while its maximum gain is 25.5 dBi and its efficiency is about 85%.
32.	Farahbakhsh, A., et al. (författare) A wideband high-gain and high-efficiency slot array antenna based on groove gap waveguide 2018 Ingår i: IET Conference Publications. - : Institution of Engineering and Technology. ; 2018:CP741 Konferensbidrag (refereegranskat)abstract A groove gap waveguide based wideband high gain and high efficiency 8×8-element slot antenna array has been proposed for mmWave applications. A 16-way power divider based on groove gap waveguide is used as feeding network in this work. The antenna sub-array consists of four radiating slots that are backed by a groove gap cavity layer. The proposed antenna frequency band is from 48.8 GHz to 66.7 GHz and achieved maximum gain is about 27.4 dBi with a total efficiency of about 90 %.
33.	Farahbakhsh, A., et al. (författare) Corporate distribution networks for slot array antenna based on groove gap waveguide technology 2016 Ingår i: 10th European Conference on Antennas and Propagation, EuCAP 2016, Davos, Switzerland, 10-15 April 2016. - 2164-3342. ; , s. Art. no. 7481157- Konferensbidrag (refereegranskat)abstract This paper deals with the design of low loss wideband power dividers based on groove gap waveguide (GGW) technology. The advantages of GGW power dividers are low insertion loss, high power handling capacities, ease of fabrication and compatibility with integrated microwave networks. A 64-way power divider is designed and used as the feeding network of a 16×16-element slot antenna array at 60-GHz band. The results show that the gain and total radiation efficiency of the antenna are more than 32.5 dBi and 90% over the desired frequency range from 56 to 66.4 GHz.
34.	Farahbakhsh, A., et al. (författare) D-Band Slot Array Antenna Using Combined Ridge and Groove Gap Waveguide Feeding Network 2019 Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019. Konferensbidrag (refereegranskat)abstract In this paper, the design of a cavity-backed slot array antenna based on combination of ridge and groove gap waveguide for D-band applications is investigated. The proposed subarray has 2×2 slots with impedance bandwidth of 20 % covering from 127 GHz to 155 GHz. A feeding network combining groove gap waveguide and ridge gap waveguide has been proposed also in this work. The feed network has been designed as a combination of ridge gap waveguide and E-plane groove gap waveguide to reduce the losses in the feed network of a large antenna array, thereby increasing the total efficiency of the array antenna.
35.	Farahbakhsh, A., et al. (författare) Ridge gap waveguide slot antenna array with 30% bandwidth for 60-GHz applications 2017 Ingår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017. - 2164-3342. ; , s. 3050-3052 Konferensbidrag (refereegranskat)abstract This paper presents a wideband high efficiency slot antenna array based on ridge gap waveguide technology at 60 GHz for millimeter-wave applications. The antenna sub-array consists of four radiating slots that are excited by a cavity. Some tuning pins are placed inside the cavity to achieve wideband performance. A 4×4 slots array antenna is designed using 4-ways power divider. The proposed structure exhibits 30% impedance bandwidth (\|S11\|
36.	Farahbakhsh, A., et al. (författare) Single Layer Antenna based on Gap Waveguide Technology with Dual-Circular Polarization for 60-GHz Band 2023 Ingår i: 17th European Conference on Antennas and Propagation, EuCAP 2023. Konferensbidrag (refereegranskat)abstract A dual-circularly polarized antenna element based on E-plane groove gap waveguide (GGW) for 60 GHz applications is presented in this work. The simulated return loss of the antenna is better than -10 dB for both polarizations in the working frequency bandwidth of antenna covering from 58 GHz to 62 GHz. The axial ratio of the proposed antenna is better than 2.5 dB in the whole bandwidth. The simulation results prove that the proposed antenna element is a good candidate to design larger array with dual circular polarization for different wireless applications at millimeter wave frequency range.
37.	Farjana, Sadia, 1983, et al. (författare) Low Loss Gap Waveguide Transmission line and Transitions at 220-320 GHz Using Dry Film Micromachining 2021 Ingår i: IEEE Transactions on Components, Packaging and Manufacturing Technology. - 2156-3985 .- 2156-3950. ; 11:11, s. 2012-2021 Tidskriftsartikel (refereegranskat)abstract This paper presents a novel microfabrication technique to manufacture gap waveguide components operating at sub-millimeter wave (sub-mmWave) frequency range. The conventional metal waveguide component manufacturing has a low resolution and low throughput and is not suitable for applications above 100 GHz. The micromachining techniques have matured and applied in various applications. Several micromachining techniques have been developed to address the specification requirements of different fields. Conventional micromachining techniques suffer from fabrication issues such as non-vertical sidewall, non-uniform surface, and time-consuming fabrication process. The proposed dry film photoresist offers significant amount of benefits such as fewer processing steps, reduced production cost, shorter prototyping time over existing micromachine techniques. To validate the proposed fabrication method, SUEX dry film photoresist is used to demonstrate three gap waveguide transmission lines. Different transitions from rectangular waveguide (RW) to gap waveguide (GW) have also been designed to characterize the newly fabricated gap waveguide components with a standard measurement setup. All the designed and fabricated device operates from 220 GHz to 320 GHz. The fabricated devices showed a good agreement with the simulation result over this frequency band and the measured average insertion losses were in the order of 0.048 dB/mm and 0.075 dB/mm for groove gap waveguide and ridge gap waveguide respectively. Thus, dry film photoresist provides fabrication precision of the structures and consequently opens the path for low-cost fabrication of high-frequency waveguide components.
38.	Farjana, Sadia, 1983, et al. (författare) Micromachined Ridge Gap Waveguide Transmission Line and Transition at 220-310 GHz 2021 Ingår i: 2021 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, APS/URSI 2021 - Proceedings. - 9781728146706 ; , s. 1297-1298 Konferensbidrag (refereegranskat)abstract This paper presents a vertical wideband transition between a standard WR-3.4 rectangular waveguide (RW) and ridge gap waveguide (RGW) operating at 220-310 GHz. To achieve a wideband impedance matching a capacitive stub is used instead of multiple steps in the ridge section to reduce the manufacturing complexity. The designed back-to-back transition is fabricated with SUEX dry film photoresist. The attractive features of the designed transition are simplicity and high tolerances to manufacturing errors, without compromising the wideband performance. The measurement results of the fabricated prototype show good agreement with simulations over the frequency band of interest and the measured average insertion loss is 0.075 dB/mm and the measured input reflection coefficient is below -12 dB for the back-to-back structure. Measurement results indicate that SUEX dry film photoresist is a suitable material to fabricate waveguide components operating at and above the millimeter-wave range.
39.	Farjana, Sadia, 1983, et al. (författare) Micromachined Wideband Ridge Gap Waveguide Power Divider at 220-325 GHz 2022 Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 10, s. 27432-27439 Tidskriftsartikel (refereegranskat)abstract A micromachined ridge gap waveguide power divider operating at 220-325 GHz is presented. The device is fabricated by SUEX dry film photoresist. Dry film photoresist can be used to obtain geometrical features with high accuracy using a robust fabrication process. The designed power divider has simple geometrical features and a wide band performance. The measured transmission coefficients are equal to -3.5 ± 0.4 dB at 220-325 GHz and the measured input reflection coefficient is below -12 dB at 220-325 GHz. The measurement results are in good agreement with simulations, demonstrating that the proposed fabrication method is suitable for the fabrication of waveguide components operating at the millimeter and sub-millimeter wave range. The presented low-loss ridge gap waveguide power divider may enable cost-effective and rapid fabrication of passive devices such as high gain antennas operating up to THz frequencies.
40.	Farjana, Sadia, 1983, et al. (författare) Multilayer Dry Film Photoresist Fabrication of a Robust >100 GHz Gap Waveguide Slot Array Antenna 2023 Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 11, s. 43630-43638 Tidskriftsartikel (refereegranskat)abstract This article presents the first use of a multilayer dry film photoresist to fabricate a slot array antenna by micromachining. The proposed fabrication process demonstrates a straightforward and fast method of realizing antenna structures and delicate features with very high accuracy above 100 GHz. The slot array antenna design is based on gap waveguide technology. The designed antenna consists of two layers: a slot layer and a feed layer with a transition to measuring waveguide. The antenna contains structures that require a multiple level dry film fabrication process with thicknesses ranging from 80 μm to 400 μm with ± 10 μm tolerance. The fabricated antenna shows good accuracy. To make the fabricated antenna layers conductive, the fabricated polymer antenna was coated with Ti and Au. The input reflection coefficient was measured to be below – 11 dB over a 10% bandwidth from 136-148 GHz, and the antenna gain was measured to be 11.4 dBi at 142 GHz, both of which are in fair agreement with simulations. A thermal cycling test has been conducted on the fabricated antenna and the results show insignificant degradation at least up to 300 cycles in the temperature range –50 °C to 135 °C which is the typical temperature gradient range for many practical outdoor wireless applications.
41.	Farjana, Sadia, 1983, et al. (författare) Pick and place assembly technique for fabrication of groove gapwaveguide resonator 2017 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 922:1 Konferensbidrag (refereegranskat)abstract Gap waveguide are an innovative technology for millimeter-wave RF applications. There are some factors to be considered while using this technology at millimeter wave frequencies or above, particularly for low cost RF applications. Surface mount technology and pick and place machine technique can demonstrate a way to solve this problem. In this paper a groove resonator is presented which is manufactured by using pick and place technique. Brass pins of diameter 1.6mm and height 2.3mm was mounted on a 5mm thick copper plate. Lead free solder paste was used for solder joint.
42.	Farjana, Sadia, 1983, et al. (författare) Polymer based 140 GHz Planar Gap Waveguide Array Antenna for Line of Sight (LOS) MIMO Backhaul Links 2019 Ingår i: IMWS-AMP 2019 - 2019 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728109350 ; July 2918, s. 148-150 Konferensbidrag (refereegranskat)abstract This paper presents the micromachining based fabrication process of a 140 GHz planar antenna array based on gap waveguide technology to be used in next generation backhauling links. Each antenna element in the bigger 3D-array to be used in LOS MIMO configuration designed to have about 30dBi gain. Each antenna element in the big array consists of several metal layers such as the cavity backed radiation layer and a corporate feed network layer. In this work, we focus on the single antenna array element. Considering some fabrication difficulties as well as focusing on batch fabrication, three different micromachine techniques, SU8 fabrication, PDMS molding and injection molding of polymer OSTEMER has been utilized to fabricate the single antenna device.
43.	Farjana, Sadia, 1983, et al. (författare) Realizing a 140 GHz Gap Waveguide–Based Array Antenna by Low-Cost Injection Molding and Micromachining 2021 Ingår i: Journal of Infrared, Millimeter and Terahertz Waves. - : Springer. - 1866-6892 .- 1866-6906. ; 42:8, s. 893-914 Tidskriftsartikel (refereegranskat)abstract This paper presents a novel micromachining process to fabricate a 140 GHz planar antenna based on gap waveguide technology to be used in the next-generation backhauling links. The 140 GHz planar array antenna consists of three layers, all of which have been fabricated using polymer-based microfabrication and injection molding. The 140 GHz antenna has the potential to be used as an element in a bigger 3D array in a line-of-sight (LOS) multiple input multiple output (MIMO) configuration to boost the network capacity. In this work, we focus on the fabrication of a single antenna array element based on gap waveguide technology. Depending on the complexity of each antenna layer’s design, three different micromachining techniques, SU8 fabrication, polydimethylsiloxane (PDMS) molding, and injection molding of the polymer (OSTEMER), together with gold (Au) coating, have been utilized to fabricate a single 140 GHz planar array antenna. The input reflection coefficient was measured to be below − 11 dB over a 14% bandwidth from 132 to 152 GHz, and the antenna gain was measured to be 31 dBi at 140 GHz, both of which are in good agreement with the simulations. © 2021, The Author(s).
44.	Ferrando-Rocher, Miguel, et al. (författare) 8 x 8 Ka-Band Dual-Polarized Array Antenna Based on Gap Waveguide Technology 2019 Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 67:7, s. 4579-4588 Tidskriftsartikel (refereegranskat)abstract This paper describes an 8 x 8 fully metallic high-efficiency dual-polarized array antenna working at the Ka-band, based on the gap waveguide (GW) concept. The radiating element is a circular aperture backed by two stacked cylindrical cavities, which are orthogonally fed to achieve a dual-polarized performance. Both feeding layers consist of a GW corporate network to reach all the cavities backing each radiating element. Cavities are naturally integrated within the bed of nails hosting grooves and ridges for the guiding electromagnetic (EM) field, leading to a low-profile dual-polarized array in the Ka-band. The experimental results present good agreement with simulations. The measured radiation patterns agree well with the simulation and the antenna provides an average gain over 27 dBi within its operating bandwidth (29.5-31 GHz).
45.	Ferrando-Rocher, M., et al. (författare) A dual-polarized slotted-waveguide antenna based on gap waveguide technology 2017 Ingår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017. ; , s. 3726-3727 Konferensbidrag (refereegranskat)abstract Euraap.This paper describes a wide-band dual-polarized slotted-waveguide antenna working at V-band (57-66 GHz) based on Gap Waveguide concept. The antenna has three layers. The first one (feeding-layer 1) is practically identical to the second one (feeding-layer 2). This optimizes the design and facilitates manufacturing. The corporate-feeding networks on the two layers are rotated 90 degrees to each other to get the two orthogonal polarizations. Radiating elements are square apertures located on the top of the antenna. Simulated results show both impedance bandwidth and radiation pattern bandwidth greater than 15% for both polarizations.
46.	Hamedani, Mahsa, et al. (författare) Planar H-Plane Horn Antenna Based on Groove Gap Waveguide Technology 2020 Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 19:2, s. 302-306 Tidskriftsartikel (refereegranskat)abstract H-plane horn antenna using gap waveguide technology is proposed. The advantage of this technology is its air-filled feature, which improves the impedance matching compared with substrate integrated waveguide (SIW) horn antennas. Corrugated walls as soft surfaces are used on the outer surfaces of the upper and lower horn plates, which act as barriers around the aperture of the antenna and reduce its backlobe levels. The bandwidth of the antenna for $\| {{S_{11}}} \|$< -10 dB is 19-28 GHz and the gain varies between 8.5 and 12 dBi. The total efficiency is better than 88% in the operation bandwidth. This structure has the capability of easily integrating with other planar microwave components. As a demonstration, a coupled-resonator filter is integrated with the antenna to select the desired frequency band and cancel the out-of-band harmonics. For the proof of concept, a prototype model is fabricated and tested, where measurement data agree well with the simulation results.
47.	Hassona, Ahmed Adel, 1988, et al. (författare) Compact Low-Loss Chip-to-Waveguide and Chip-to-Chip Packaging Concept Using EBG Structures 2021 Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 31:1, s. 9-12 Tidskriftsartikel (refereegranskat)abstract This letter presents a novel approach for packaging millimeter-wave (mmW) and terahertz (THz) circuits. The proposed technique relies on using an on-chip coupling structure that couples the signal to a quarter-wavelength cavity, which in turn couples to either a waveguide (WG) or another chip. The solution also uses a periodic electromagnetic bandgap (EBG) structure that controls the electromagnetic wave and prevents field leakage in undesired directions. The proposed solution is fabricated and demonstrated at the D-band (110-170 GHz), and the measurement results show that it achieves a minimum insertion loss of 0.8 and a 3-dB bandwidth extending from 124 to 161 GHz. The proposed approach does not require any galvanic contacts and can be used for packaging integrated circuits in WG modules as well as for chip-to-chip communication.
48.	Hassona, Ahmed Adel, 1988, et al. (författare) D-band waveguide-to-microstrip transition implemented in eWLB packaging technology 2020 Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 56:4, s. 187- Tidskriftsartikel (refereegranskat)abstract This Letter presents a non-galvanic D-band (110-170 GHz) interconnect realised in embedded wafer level ball grid array (eWLB) packaging technology. The interconnect consists of a patch-radiator-based waveguide transition implemented using one of the technology's redistribution layers. The patch radiates to a WR-6.5 standard waveguide perpendicular to its plane. An electromagnetic band-gap structure realised by metal patches is used to suppress undesired modes and improve the performance of the transition. The proposed solution is experimentally verified, and measurement results show that the transition exhibits an average insertion loss of 2 dB across the frequency range 122-146 GHz which, to the best of the authors' knowledge, is the lowest reported loss for a D-band packaging solution in eWLB technology and hence addresses one of the main integration challenges facing millimetre-wave systems.
49.	Hassona, Ahmed Adel, 1988, et al. (författare) Nongalvanic Generic Packaging Solution Demonstrated in a Fully Integrated D-Band Receiver 2020 Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 10:3, s. 321-330 Tidskriftsartikel (refereegranskat)abstract This article presents a packaging technique for monolithic microwave integrated circuits (MMIC) demonstrated in a fully integrated receiver (Rx) module at the D -band (110–170 GHz). The solution consists of an MMIC-to-waveguide transition realized using an on-chip probe mounted in the E -plane of a split-block waveguide module. An artificial magnetic conductor structure is implemented to suppress cavity modes and achieve better coupling from the waveguide to the probe. The transition's performance is experimentally verified using a back-to-back test chip, and measurement results show that the proposed packaging solution achieves a low insertion loss of only 0.7 dB and covers a very wide frequency range extending from 105 to 175 GHz. The proposed transition is also integrated with an in-phase/quadrature-phase (I/Q) Rx on the same chip. The Rx is realized in a 250-nm indium phosphide double heterojunction bipolar transistor technology and consists of a low-noise amplifier, an I/Q mixer, and a frequency tripler. Measurement results show that the Rx module achieves an average conversion gain of 23 dB across the frequency range of 110–145 GHz and has an average noise figure of 10.6 dB. The Rx MMIC has a dc power consumption of 440 mW and occupies an area of 1.6 × 1.6 mm 2 . This article addresses one of the main challenges in systems operating above 100 GHz and presents a fully integrated packaging solution that suits large integrated circuits and does not require any galvanic contacts nor impose any limitations on MMIC dimensions.
50.	Hassona, Ahmed Adel, 1988, et al. (författare) Packaging Technique of Highly Integrated Circuits Based on EBG Structure for +100 GHz Applications 2020 Ingår i: 14th European Conference on Antennas and Propagation, EuCAP 2020. Konferensbidrag (refereegranskat)abstract This work presents an on-chip packaging concept suitable for monolithic microwave integrated circuits (MMIC) operating above 100 GHz. The concept relies on using an on-chip transition that couples the signal to a standard air-filled waveguide. The proposed solution utilizes an electromagnetic band-gap (EBG) structure realized using bed of nails to prevent the propagation of parallel plate modes and improve the coupling between the MMIC and the waveguide. The technique shows an average insertion loss of only 0.6 dB across the frequency range 110 - 155 GHz. Moreover, the concept is demonstrated in a D-band amplifier circuitry that is fabricated in an indium phosphide (InP) double heterojunction bipolar transistor (DHBT) technology. Experimental results show that the amplifier exhibits a maximum gain of 18.5 dB with no sign of propagation of any parallel plate modes. This work presents a verified solution for packaging high-frequency integrated circuits, and hence paves the way towards higher system integration above 100 GHz.

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