IEEE Antennas and Wireless Propagation Letters

Ieee transactions on antennas and propagation

Ground Penetrating Radar : Theory and Applications

In this paper, a novel multi-stream spatial digital predistortion (DPD) technique is proposed to model and linearize the fully-connected (FC) hybrid beamforming (HBF) transmitters. The proposed scheme solves the DPD implementation issue in the FC HBF array by estimating and linearizing the beam signals instead of the individual PAs. In FC HBF systems, significant intermodulation (IMD) between different transmit signals will be generated due to the analog beamforming and combining network upstream of the power amplifiers (PAs). The IMD beams will end up being radiated in different directions and some of them might fall in the linear beam directions. Therefore, multi-input DPD blocks using a practical multi-variable model are constructed for each RF chain to eliminate the complicated inner- and cross-channel IMDs of the beam signals. Simulations on a 4-stream 64-element FC HBF array and experimental tests on a 2-stream 4-element system are carried out to benchmark the proposed DPD technique against the conventional techniques. Better than 13 dB adjacent channel power ratio (ACPR) improvement and 12 dB normalized mean square error (NMSE) improvement have been achieved by the proposed DPD technique.

Multi-Stream Spatial Digital Predistortion for Fully-Connected Hybrid Beamforming Massive MIMO Transmitters

Mid-air collisions (MACs) are commonly caused by temporary or permanent loss of flight control resulting in catastrophic damages and hence must be countered with suitable technology. The avionic industry has been using Traffic Alert and Collision Avoidance System (TCAS) for avoiding mid-air collisions since 1987. The TCAS either uses an Omni-directional antenna or a directional antenna for the surveillance of other nearby aircraft. The existing TCAS directional antennas, i.e., an array of monopole antennas are characterized by a maximum gain of 3.6 dB, which is regarded as low. As a result, many research has been carried out to find the alternative for the TCAS antenna and have found microstrip patch antenna (MPA) which yield some promising results such as feed flexibility, multiband, beam steering, etc. However, the MPA still suffers from disadvantages such as low gain and narrow bandwidth. Hence, lately, a tremendous amount of work has been carried out to enhance the gain of the MPA. In this paper, we first review the key methods that has been reported so far to improve the gain of the traditional TCAS antenna. We note that, in most of the reported work, conventional techniques such as parasitic patches, and shorting pins are used to improve the gain of MPA, and no substantial work was done using advanced techniques such as electromagnetic-band gap (EBG), metamaterials and metasurfaces. Hence, we further review the work that has been carried out to improve the gain of vertically polarized MPAs using advanced techniques for L- and S-band (up to 3 GHz). Many advanced structures that are easily adapted to enhance the gain of TCAS antenna are thoroughly discussed in this work.

/pdf/a-review-on-gain-enhancement-techniques-for-vertically-li8poa8ts4.pdf

A Review on Gain Enhancement Techniques for Vertically Polarized Mid-Air Collision Avoidance Antenna for Airborne Applications

In this paper, a design of ultra-wideband microstrip array antenna using a stepped line cut and U-slot combination for 5G millimeter-wave applications is proposed. The feeding technique used in the proposed design is a proximity coupling technique to improve bandwidth performance. The proposed antenna bandwidth performance is compared with the conventional antenna array design to determine the bandwidth increase. Numerical and simulation results show a significant increase in bandwidth performance compared to conventional design. The proposed antenna design can operate at frequency band 28 GHz with a bandwidth 4.47 GHz and gain 8.71dB. These results prove that the proposed antenna design can be used for 5G technology applications in the millimeter-wave band. 

/pdf/ultra-wideband-microstrip-array-antenna-for-5g-millimeter-4i8wes5daf.pdf

Ultra-wideband Microstrip Array Antenna for 5G Millimeter-wave Applications

In this paper, design of multiband MIMO antenna by using patch and slot modification is proposed. The MIMO multiband antenna design uses the addition and modification of patch and slot shapes to obtain antenna performance in several frequency bands. In a previous study, the multiband antenna design only used the method of adding patches or slots separately. In this research, we tried to combine the addition of patches and slots together. The antenna design uses the substrate material Rogers RT5880 with a dielectric constant (er ) 2.2 and height 0.787 mm. The dimensions of the MIMO multiband antenna developed by this study are 42.90 × 14.89 mm. Simulation and measurement results show that this MIMO antenna can work on several millimeter-wave frequency bands, 24 GHz, 28 GHz and 38 GHz. These results prove that the development of design techniques by adding patches and slots to microstrip antennas can produce antennas that work in several frequency bands.

https://iopscience.iop.org/article/10.1088/1757-899X/852/1/012154/pdf

Design of Multiband MIMO Antenna for 5G Millimeterwave Application

Ground Penetrating Radar (GPR) is one of radar types that is often used to determine conditions inside or below some surface. GPR is also commonly used as a material evaluation tool by its trait as a non-destructive testing (NDT). One of the most important sections of GPR is signal processing system or GPR data processing that will filter all of the GPR survey results. Reflection signals gained by the radar antenna are then filtered to discover any objects located below the ground surface. The better the process in filtering data, the more accurate the GPR interprets the gained signal. This study aims to design a GPR data processing system that is sufficiently be able to interpret the gained signal so that it can accurately discover any objects located on the ground. This GPR data processing system is expected to work on a variety of frequencies and the application can be developed in various types. The aims of this study are designing and modifying the GPR data processing system.

/pdf/the-development-of-ground-penetrating-radar-gpr-data-2aezksg732.pdf

The Development of Ground Penetrating Radar (GPR) Data Processing

https://iopscience.iop.org/article/10.1088/1742-6596/1402/4/044032/pdf

Design of substrate integrated waveguide to improve antenna performances for 5G mobile communication application

Reducing system complexity and cost in synthesizing a sparse array antenna design is a challenging task for practical communication systems, such as radar systems and space communication. In this paper, a hybrid technique to synthesize a linear sparse array antenna design is described. This technique is developed using two methods. The first method is a combinatorial approach that applies cyclic difference sets (CDS) integers to significantly reduce the number of antenna elements. The approach and procedure used to apply the new CDS method to configure a linear sparse array, with significant reduction of the spatial antenna dimension, is described. The second method, applied to the array result of the first method, is amplitude tapering using a binomial array approach to reduce the sidelobes level (SLL). The simulation and measurement results of the sample sparse array design showed that the SLL was reduced in comparison to the sparse array design using only the combinatorial CDS method.

http://aemjournal.org/index.php/AEM/article/download/432/pdf

A Hybrid Technique Using Combinatorial Cyclic Difference Sets and Binomial Amplitude Tapering for Linear Sparse Array Antenna Design

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