| 1. |
- Oloumi, Daniel, et al.
(author)
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A Modified TEM Horn Antenna Customized for Oil Well Monitoring Applications
- 2013
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In: IEEE Transactions on Antennas and Propagation. - : IEEE. - 0018-926X. ; 616:12, s. 5902-5909
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Journal article (peer-reviewed)abstract
- A TEM horn antenna with modified radiation pattern customized for oil well monitoring application is presented in this paper. The antenna is designed to operate in an oil saturated medium in the frequency range between 1.4 to 11 GHz. A complete design procedure for the proposed TEM horn antenna with a method to modify the radiation pattern is introduced here. The modification is conducted using non-uniform expansion of the antenna flares. Applying this technique eliminates ripples in the antenna’s main-lobe radiation pattern at higher frequencies, a problem which exists for conventional TEM horn antennas. The design coefficients which control the flare openings are optimized using CST Microwave Studio to achieve smooth main-beam radiation patterns while maintaining return loss more than 10dB. Simulations are performed both in oil and free space. Free space simulations are done to provide a valid reference for antenna radiation pattern measurement as radiation pattern cannot be measured in oil. Simulation results are followed by the measurement results with a very good agreement. The fabricated dimensions of the antenna including balun section are limited to 89.2×49.2×78.2 mm. The designed antenna is utilized as a part of an ultra-wideband radar system for oil well monitoring.
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| 2. |
- Oloumi, Daniel, et al.
(author)
-
A TEM Horn Antenna with Non-uniform Expansion for Oil Well Monitoring
- 2012
-
Conference paper (peer-reviewed)abstract
- A TEM horn antenna with non-uniform expansion to modify the radiation characteristics, operating from 1.4 to 11 GHz in oil medium is introduced. Main lobe radiation pattern ripple at higher frequencies which are the problem of conventional TEM horn antenna is suppressed. The expansions coefficient is tuned using CST Microwave Studio to achieve good return loss (less than 10dB) and radiation pattern. The horn is utilized as a part of an ultra-wideband radar system to monitor oil well with no metal casing.
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| 3. |
- Oloumi, Daniel, et al.
(author)
-
Dual-band orthogonally-polarized slotted-Lozenge reflective unit cell tuned by MEMS varactor
- 2012
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Conference paper (peer-reviewed)abstract
- A novel dual-band orthogonally-polarized MEMS reconfigurable slotted-Lozenge patch is introduced here. The dual-band performance of the lozenge patch (12 and 14 GHz) is due to different diagonal length. A cross slot is etched in the middle of patch to control the phase swing in each frequency and polarization. The effective slot length is controlled by MEMS capacitors with capacitance ratio of 1.5 resulting in phase swing of 345°. The reflect-array composed of this cell element would be able to radiate two independent beams at different frequencies and polarizations.
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| 4. |
- Oloumi, Daniel, et al.
(author)
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Gain compensation of a printed log periodic dipole array antenna by cutting-away the dielectric between radiating elements
- 2011
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Conference paper (peer-reviewed)abstract
- This paper introduces a simple technique to compensate the lost gain due to the dielectric loss of the printed log periodic dipole array (PLPDA) antenna. First, a simple Printed LPDA is designed then by removing the dielectric between radiating elements, the PLPDA is changed into Cut PLPDA (CPLPDA). This change causes to compensate antenna gain by 1 dB approximately. Moreover, a simultaneously weight reduction of more than half is likely to happen. Observing the characteristics of both antennas shows that main antenna properties such as radiation pattern, and return loss are maintained during this modification. The proposed structures are simulated by CST Microwave Studio software and are fabricated on both sides of FR4 substrate with =4.5 and 2.4mm thickness. At the end, the simulated results are confirmed by the measured results with excellent agreements.
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| 5. |
- Oloumi, Daniel, et al.
(author)
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Imaging of oil-well perforations using UWB synthetic aperture radar
- 2015
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In: IEEE Transactions on Geoscience and Remote Sensing. - : IEEE. - 0196-2892 .- 1558-0644. ; 53:8, s. 4510-4520
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Journal article (peer-reviewed)abstract
- Ultrawideband (UWB) synthetic aperture radar (SAR) as a tool for oil well perforation monitoring is experimentally investigated in this paper. Experiments are conducted on a lab prototype that emulates the small section of an oil well. Oil well perforations are scanned using the designed UWB radar system for different experimental conditions. High-resolution images in both down-range and cross-range are obtained by using UWB pulses and signal processing. High-quality images are constructed using SAR processing algorithm with the proposed modifications. Experiments are carried out for different perforation conditions such as open, partially clogged and fully clogged cases. It is shown by the experiments that the proposed radar technique and the data processing methods are capable of providing more revealing high-quality images. This approach can be applied effectively to monitor the oil well medium and detect well impairment locations.
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| 6. |
- Oloumi, Daniel, et al.
(author)
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Miniaturized Reflectarray Unit Cell Using Fractal-Shaped Patch-Slot Configuration
- 2012
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In: IEEE Antennas and Wireless Propagation Letters. - : IEEE. - 1536-1225 .- 1548-5757. ; 11, s. 10-13
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Journal article (peer-reviewed)abstract
- This letter introduces a new class of miniaturized reflectarray unit cells with increased phase swing employing Minkowski fractal-shaped patch-slot elements. Square, 1st Minkowski, and 2nd Minkowski fractal patches are designed as a reflectarray unit cell. A slot with variable lengths of mm is used in the ground plane to perform the phase variation function. The resonant frequency corresponding to the maximum phase swing is reduced from 10.6 GHz for the square patch down to 8.8 and 8.3 GHz for the first-and second-order Minkowski fractal patches, respectively, which is equivalent to 17% and 22% size reduction. Unit cells with different patch type and slot length are fabricated, and close agreement is observed between the measured and simulated results. As it has been proven for conventional phased array antennas, this size reduction can lead to a decrease in mutual coupling in reflectarray antennas. Alternatively, it allows for smaller distance between reflectarray antenna elements, which renders a wider beam-scanning range.
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