Through Wall Imaging Radar Antenna with a Focus on Opening New Research Avenues

This review paper is an effort to develop insight into the development in antennas for through wall imaging radar application. Review on literature on antennas for use in through wall imaging radar, fulfilling one or more requirements/specifications such as ultrawide bandwidth, stable and high gain, stable unidirectional radiation pattern, wide scanning angle, compactness ensuring portability and facilitating real-time efficient and simple imaging is presented. The review covers variants of Vivaldi, Bow tie, Horn, Spiral, Patch and Magneto-electric dipole antennas demonstrated as suitable antennas for the through wall imaging radar application. With an aim to open new research avenues for making better through wall imaging radar antenna, review on relevant compressive reflector antennas, surface integrated waveguide antennas, plasma antennas, metamaterial antennas and single frequency dynamically configurable meta-surface antennas are incorporated. The review paper brings out possibilities of designing an optimum through wall imaging radar antenna and prospects of future research on the antenna to improve radiation pattern and facilitate overall simple and efficient imaging by the through wall imaging radar

Antenna Designs Aiming at the Next Generation of Wireless Communication

Millimeter-wave (mm-wave) frequencies have drawn large attention, specically for the fifth generation (5G) of wireless communication, due to their capability to provide high data-rates. However, design and characterization of the antenna system in wireless communication will face new challenges when we move up to higher frequency bands. The small size of the components at higher frequencies will make the integration of the antennas in the system almost inevitable. Therefore, the individual characterization of the antenna can become more challenging compared to the previous generations.This emphasizes the importance of having a reliable, simple and yet meaningful Over-the-Air (OTA) characterization method for the antenna systems. To avoid the complexity of using a variety of propagation environments in the OTA performance characterization, two extreme or edge scenarios for the propagation channels are presented, i.e., the Rich Isotropic Multipath (RIMP) and Random Line-of-Sight (Random-LoS). MIMO efficiency has been defined as a Figure of Merit (FoM), based on the Cumulative Distribution Function (CDF) of the received signal, due to the statistical behavior of the signal in both RIMP and Random-LoS. Considering this approach, we have improved the design of a wideband antenna for wireless application based on MIMO efficiency as the FoM of the OTA characterization in a Random-LoS propagation environment. We have shown that the power imbalance and the polarization orthogonality plays major roles determining the 2-bitstream MIMO performance of the antenna in Random-LoS. In addition, a wideband dual-polarized linear array is designed for an OTA Random-LoS measurement set-up for automotive wireless systems. The next generation of wireless communications is extended throughout multiple narrow frequency bands, varying within 20-70 GHz. Providing an individual antenna system for each of these bands may not be feasible in terms of cost, complexity and available physical space. Therefore, Ultra-Wideband (UWB) antenna arrays, coveringmultiple mm-wave frequency bands represent a versatile candidate for these antenna systems. In addition to having wideband characteristics, these antennas should offer an easy integration capability with the active modules. We present a new design of UWB planar arrays for mm-wave applications. The novelty is to propose planar antenna layouts to provide large bandwidth at mm-wave frequencies, using simplified standard PCB manufacturing techniques. The proposed antennas are based on Tightly Coupled Dipole Arrays (TCDAs) concept with integrated feeding network

Unveiling Magnetic Dipole Radiation in Phase-Reversal Leaky-Wave Antennas

The radiation principle of travelling-wave type phase-reversal antennas is explained in details, unveiling the presence of magnetic-dipole radiation in addition to well-known electric dipole radiation. It is point out that such magnetic dipole radiation is specific to the case of traveling-wave phase-reversal antennas whereas only electric-dipole radiation exists in resonant-type phase-reversal antennas. It is shown that a phase-reversal travelling-wave antenna alternately operates as an array of magnetic dipoles and an array of electric-dipoles during a time-harmonic period. This radiation mechanism is confirmed through both full-wave and experimental results.Comment: 4 pages, 3 figure

Design of a low-profile wideband patch antenna with L-shaped feeding mechanism

This paper has presented the design of a novel low-profile wideband patch antenna. The antenna structure is formed of three layers of substrates with the radiating patches on the top, the grounded patches in the middle and the feeding portion at the bottom. The large operating frequency bandwidth has been obtained due to the L-shaped feeding technique. Moreover, the low cross-polarization level can also be achieved as the feeding structure can be regarded as the preferred differential feeding. The obtained results can confirm that the proposed antenna has achieved a wide impedance bandwidth (VSWR ≤ 2) of about 60% (3-5.5 GHz) and the whole height of the antenna is 6 mm (around 0.06λ l at the lowest operating frequency). The obtained cross-polarization level is less than-30dB compared with co-polarization

A Wideband Differentially Fed Dual-Polarized Antenna with Stable Radiation Pattern for Base Stations

© 1963-2012 IEEE. A new wideband differentially fed dual-polarized antenna with stable radiation pattern for base stations is proposed and studied. A cross-shaped feeding structure is specially designed to fit the differentially fed scheme and four parasitic loop elements are employed to achieve a wide impedance bandwidth. A stable antenna gain and a stable radiation pattern are realized by using a rectangular cavity-shaped reflector instead of a planar one. A detailed parametric study was performed to optimize the antenna's performances. After that, a prototype was fabricated and tested. Measured results show that the antenna achieves a wide impedance bandwidth of 52% with differential standing-wave ratio <1.5 from 1.7 to 2.9 GHz and a high differential port-to-port isolation of better than 26.3 dB within the operating frequency bandwidth. A stable antenna gain (≈8 dBi) and a stable radiation pattern with 3-dB beamwidth of 65° ±5° were also found over the operating frequencies. Moreover, the proposed antenna can be easily built by using printed circuit board fabrication technique due to its compact and planar structure

BANDWIDTH BOUNDS OF INFINITE PLANAR ARRAY ELEMENTS

For elements of an infinite planar phased array in free space and an infinite conductor-backed free standing planar phased array, fundamental bandwidth bounds are derived from the optical theorem for periodic scatterers. The bounds are based on Gustafsson’s theory of fundamental bandwidth limits for electrically small antennas of arbitrary shape, but extended to periodic configurations. The element bandwidth bound is found to be a function of the strengths of the induced static dipole moments in constant background fields as well as the unit-cell dimensions and the scan angle. Explicit bandwidth bound expressions are found for narrowband and ultrawideband array cases. For elements of an infinite conductor-backed planar phased array with a dielectric substrate, fundamental bandwidth bounds are derived by Doane based on the Fano’s method. A general conductor-backed array is modeled as transmission line terminate with a shorted load. The input reflection coefficient is expanded in long wavelength limit and Fano’s method is used to determine a limit for the frequency integral of the reflection coefficient. This yields the bandwidth bound for the array. In this dissertation, the reflection coefficients were expanded into high order terms. Then, Fano limit is invoked to have the higher-order bandwidth bound. Such bandwidth bound depends on the physical features (scan angle, ground separation, unit-cell area) and electric feature (dipole strength). All bandwidth bound are numerically tested using example array designs. The following time-harmonic analysis, an e^jωt time convention is assumed and suppressed. Peak phasors are used for source and field quantities

2009 Index IEEE Antennas and Wireless Propagation Letters Vol. 8

This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author\u27s name. The primary entry includes the coauthors\u27 names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author\u27s name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index

2008 Index IEEE Transactions on Control Systems Technology Vol. 16

This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author\u27s name. The primary entry includes the coauthors\u27 names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author\u27s name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index