| 1. |
-
A wideband frequency selective surface reflector for 4G/X-Band/Ku-Band
- 2018
-
Ingår i: Progress In Electromagnetics Research C. - : Electromagnetics Academy. - 1937-8718. ; 81, s. 151-159
-
Tidskriftsartikel (refereegranskat)abstract
- A Frequency Selective Surface (FSS) reflector with wideband response for 4G/X-band/Ku-band is proposed. The wideband FSS reflector consists of cascaded dual-layer patch FSS which is etched on separate layers of FR4 substrate. The targeted frequency range is 5–16 GHz. A wide stopband of 10.4 GHz (100% percent bandwidth) is obtained with two layers in cascade. The Equivalent Circuit (EC) method is used to approximate the simulated results. An extensive parametric study is also carried out to understand the effect of various combinations of FSS layers and their disposition. A panel of final FSS is fabricated where measured and simulated results agree well.
|
|
| 2. |
- Bembarka, Aicha, et al.
(författare)
-
Frequency Tunable Filtenna Using Defected Ground Structure Filter in the Sub-6 GHz for Cognitive Radio Applications
- 2022
-
Ingår i: Progress In Electromagnetics Research C. - 1937-8718. ; 118, s. 213-229
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a new frequency tunable filtering-antenna (so-called filtenna) is inspired by a Defected Ground Structure (DGS) band-pass filter for the fifth generation picocell base stations. It is intended for use in Cognitive Radio (CR) communications within the European Union Sub-6 GHz spectrum, which ranges between 3.4 and 3.8 GHz. Firstly, a Wideband (WB) monopole antenna is proposed where the operational frequencies cover 3.15–4.19 GHz, taking the 10-dB return loss level as a threshold. A band-pass filter of a Semi-Square Semi-Circle shape is integrated into the WB antenna ground to obtain the communicating filtenna. The narrowband frequency tunability is achieved by changing two varactor diode capacitances located in the filter slots. The antenna is prototyped occupying a total space of 60 × 80 × 0.77 mm3, then tested to verify the simulated results. Three operating frequencies 3.4, 3.6, and 3.8 GHz of the filtenna are studied in terms of return loss, realized gain, and radiation patterns which verify that the frequency shift has almost no effect on the antenna performance. The filtenna has a maximum gain of 4.5 dBi in measurements and 3.47 dBi in simulations. The obtained results have proved their efficiency for CR communications.
|
|
| 3. |
- Eroglu, Abdullah, et al.
(författare)
-
Design of multilayer and multiline microstrip directional coupler with closed form relations
- 2018
-
Ingår i: Progress In Electromagnetics Research C. - : Electromagnetics Academy. - 1937-8718. ; 83, s. 1-14
-
Tidskriftsartikel (refereegranskat)abstract
- Design, simulation, implementation and measurement results of multiline and multilayer microstrip directional couplers are given with closed form relations. Step-by-step design procedure reflecting the design practice of directional couplers, which requires only information on coupling level, port impedances and operational frequency, is presented. The method based on the synthesis technique applied in the design of conventional two-line microstrip symmetrical directional couplers is adapted to design multilayer directional couplers with the aid of electromagnetic simulators using parametric analysis with curve fitting method. The proposed design method is compared with the measurement results and accuracy is verified. It has been also shown that the directivity of the couplers designed using the multilayer structure is improved significantly. A method such as the one presented in this paper can be used to design multilayer two-line and three-line directional couplers which can be integrated to the front end of an RFID systems to provide the required isolation between transmitter and receiver and prevent signal leakage due to use of conventional circulators.
|
|
| 4. |
- Frid, Henrik, et al.
(författare)
-
Optimization of Micromachined Millimeter-Wave Planar Silicon Lens Antennas with Concentric and Shifted Matching Regions
- 2017
-
Ingår i: Progress In Electromagnetics Research C. - 1937-8718. ; 79, s. 17-29
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a study of planar silicon lens antennas with up to three stepped-impedance matching regions. The effective permittivity of the matching regions is tailor-made byetching periodic holes in the silicon substrate. The optimal thickness and permittivity of the matchingregions were determined by numerical optimization to obtain the maximum wideband aperture efficiencyand smallest side-lobes. We introduce a new geometry for the matching regions, referred to as shiftedmatching regions. The simulation results indicate that using three shifted matching regions results intwice as large aperture efficiency as compared to using three conventional concentric matching regions.By increasing the number of matching regions from one to three, the band-averaged gain is increasedby 0.3 dB when using concentric matching regions, and by 3.7 dB when using shifted matching regions,which illustrates the advantage of the proposed shifted matching region design.
|
|
| 5. |
- Guo, T., et al.
(författare)
-
Scalable preparation of broadband ultrablack graphite nanoneedle surfaces through self-masked etching
- 2018
-
Ingår i: Progress In Electromagnetics Research C. - : Electromagnetics Academy. - 1937-8718. ; 81, s. 191-197
-
Tidskriftsartikel (refereegranskat)abstract
- Ultrablack materials play an essential role in astronomical observation and many thermal applications. Many material systems such as vertically aligned carbon nanotubes have produced extraordinarily high absorption, but require complicated fabrication. Here we report a single step self-masked etching process performed on compressed-coal graphite plates on a silicon substrate, which produces an ultrablack material with 0.7% hemispherical reflectance in the visible region and specular reflectance below 0.7% between 850 nm and 10 µm. Nanoscopic pieces of silicon are ripped off the substrate and deposit on the graphite resulting in carbon nanoneedle structures, which grow linearly with etching time reaching a height of 5.7 µm after 60 minutes.
|
|
| 6. |
- Ivanchenko, Igor, et al.
(författare)
-
X-band aperture antenna with hybrid dielectric inserts
- 2016
-
Ingår i: Progress In Electromagnetics Research C. - 1937-8718. ; 61, s. 27-35
-
Tidskriftsartikel (refereegranskat)abstract
- An X-band radiator as an open-ended waveguide with a hybrid dielectric insert is proposed. The insert is in the form of a parallelepiped, which fills the entire cross section of the waveguide and constitutes a Teflon matrix with local inhomogeneities in the form of dielectric cylinders with a different permittivity. The design allows for forming various near-field distributions and, hence, the radiator performance by means of definite combinations of the local inhomogeneities can be modified. A number of configurations in the location of air and quartz cylinders are investigated. The calculated and experimental results are in good agreement. The proposed approach to the near-field formation of the aperture antenna is promising, because the variety of possible configurations in the location of local inhomogeneities with different permittivity provides new opportunities in terms of designing both single radiators and antenna arrays.
|
|
| 7. |
- Månsson, Daniel, et al.
(författare)
-
Comparing analytical and numerical calculations of shielding effectiveness of planar metallic meshes with measurements in cascaded reverberation chambers
- 2012
-
Ingår i: Progress In Electromagnetics Research C. - 1937-8718. ; 31, s. 123-135
-
Tidskriftsartikel (refereegranskat)abstract
- Large electrical systems or facilities can be satisfactorily shielded by using low-cost meshed metallic nets. Here the shielding effectiveness for two such planar meshes is calculated analytically and verified both experimentally by using cascaded reverberation chambers as well as numerically with results computed using a full wave electromagnetic solver. It is shown that all three methods agree and, in addition, that non-square shaped aperture meshes can be handled with an equivalent square area shaped aperture.
|
|
| 8. |
- Razavi, Aidin, 1982, et al.
(författare)
-
Characterization method of an automotive random-LOS OTA measurement setup
- 2018
-
Ingår i: Progress In Electromagnetics Research C. - 1937-8718. ; 84, s. 47-60
-
Tidskriftsartikel (refereegranskat)abstract
- A novel characterization method of OTA test setups for wireless communication systems on vehicles in the random line-of-sight (Random-LOS) environment is proposed. The measurement setup assumes a compact range and a test zone where the antenna under test (AUT) on the vehicle would be located. An ideal receiver is assumed for the reference measurement, which allows to perform a system analysis through evaluating the Probability of Detection (PoD) as the system figure-of-merit. The proposed method is aimed as an aid for test equipment designers to design OTA compact ranges, compare their performances, and define an ideal numerical reference. The requirements for OTA measurement ranges are different from those for conventional anechoic compact ranges. A compact cylindrical reflector system with an antenna array line feed is characterized using the proposed method, from 1.6-2.7GHz, for two orthogonal polarizations, various AUT heights and reflector tilting angles, with and without ground plane in a test zone which is 2m wide in diameter.
|
|
| 9. |
- Wang, L., et al.
(författare)
-
Design of fragment-type isolation structures for MIMO antennas
- 2014
-
Ingår i: Progress In Electromagnetics Research C. - 1937-8718. ; 52, s. 71-82
-
Tidskriftsartikel (refereegranskat)abstract
- Fragment structure should find its application in acquiring high isolation between multiple-input multiple-output (MIMO) antennas. By gridding a design space into fragment cells, a fragment-type isolation structure can be constructed by metalizing some of the fragment cells. For MIMO isolation design, cells to be metalized can be selected by optimization searching scheme with objectives such as isolation, return losses, and even radiation patterns of MIMO antennas. Due to the exibility of fragment-type isolation structure, fragment-type structure has potentials to yield isolation higher than canonical isolation structures. In this paper, multi-objective evolutionary algorithm based on decomposition combined with genetic operators (MOEA/D-GO) is applied to design fragment-type isolation structures for MIMO patch antennas and MIMO PIFAs. It is demonstrated that isolation can be improved to different extents by using fragment-type isolation design. Some technique aspects related to the fragment-type isolation design, such as effects of fragment cell size, design space, density of metal cells, and efficiency consideration, are further discussed.
|
|
| 10. |
- Xiao, Fei, et al.
(författare)
-
Compact Third-Order Microstrip Bandpass Filter Using Hybrid Resonators
- 2011
-
Ingår i: Progress In Electromagnetics Research C. - 1937-8718. ; 19, s. 93-106
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a novel microwave bandpass filter structure is proposed. By introducing a metallic via hole, the filter structure operates as one λ/2 and two λ/4 uniform impedance resonators and consequently form a triplet coupling scheme. The equivalent circuit model is analyzed in detail, which shows that there is a transmission zero in the low stopband. Based on that concept, three microstrip filters are designed, fabricated and measured, respectively. The first filter has no source/load coupling and only one transmission zero is created. By introducing source/load coupling, the second filter can create three transmission zeros. The third filter can create a controllable transmission zero in upper stopband. The simulated and measured results agree very well.
|
|
