Pedram Mousavi

A compact, circularly-polarized (CP), end-fire, $4\times 1$ continuous beamsteering antenna array implemented using substrate-integrated waveguides for 5G mobile terminals is proposed in this paper. The purpose of this system is to complement the radiation patterns of planar phased arrays on the faces of a typical mobile terminal. The proposed system seamlessly integrates previously-presented antennas and polarizers, with adjustable phase shifters and a feeding network in a multi-layered, single stack, printed circuit board (PCB) for continuous beamsteering in a compact package. Through the use of forward and reverse couplers, and the stacking of the phase shifters on top of the feeding network, a compact form factor of $7.6\times 4.1\times 0.38\lambda _{o}^{3}$ is achieved. The system was fabricated and assembled through standard PCB processes. The measurements illustrated that the system can achieve a continuous beamsteering range of ±35° with an axial ratio better than 3 dB and a gain variation less than 3 dB. A measured impedance bandwidth (BW) of 8.9% at 28 GHz is also demonstrated. Given its performance, size, ease of manufacture, integrated control lines and single RF feed, the proposed system is a good candidate for 5G millimeter-wave continuous beamsteering in mobile terminals.

Hybrid analog-digital precoding has been recognized as a promising potential solution to facilitate implementation of massive multiple-input multiple-output systems in the millimeter wave spectrum. Hybrid transceivers reduce the RF chain count and cost by dividing the task of precoding between the digital and analog processing domains, but near-optimal design of the hybrid precoders is non-trivial and their optimal design is analytically intractable. This is due to the joint optimization of digital and analog precoding matrices as well as extra constraints for analog precoders due to their realization by analog phase shifters. Additionally, hybrid transceivers can be realized via two architectures, either fully-connected or partially-connected. In this paper, we make use of projection algorithms to greatly simplify the design problem of the digital baseband and analog precoders into two optimization subproblems whose optimal solutions can be found. We also incorporate in the design a simplified user clustering algorithm based on the discrete Fourier transform, where users with similar and overlapping angular bins in the beam-space domain are grouped together. Simulation results demonstrate the proposed hybrid precoding and user clustering algorithm outperforms existing algorithms.

In this paper, a new wideband resonant cavity antenna (RCA) with circular polarization is proposed. A wideband circularlypolarized (CP) crossed-dipole antenna acts as the main radiating element inside the cavity. The dipole is designed based on self-complementary structures and utilizes several parasitic patches and posts to obtain wideband circular polarization and impedance characteristic. The incorporation of the proposed antenna with a new broadband thin singlelayer dual-sided partially reflective surface (PRS) designed based on the complementary structure contributes to the improvement of the antenna gain in a broad bandwidth. The fabrication of the PRS on both sides of a thin single laminate substrate reduces thickness of the PRS compared with conventional multilayer PRS structures, in which the layers are separated by a gap distance. The measured results, which are in agreement with the simulations, show that the proposed antenna has a maximum measured gain of 12.5 dBic, while the 3-dB gain bandwidth, and 3-dB axial ratio bandwidths are 39% and 43.37%, respectively. The measured results demonstrate the wideband functionality of the proposed antenna.

In this paper, a new transmission-line-based analysis is introduced to design the gradient and Huygens’ metasurfaces. In this method, each unit cell of the gradient and Huygens’ metasurfaces is modeled by a transmission line with a specific characteristic impedance and propagation constant. By using this method, a prototype for each of the gradient and Huygens’ metasurfaces is designed and simulated. Each unit cell in the prototype consists of only one magneto-dielectric slab. Due to the difficulty of realizing the magneto-dielectric materials, a special unit cell structure consisting of three dielectric slabs is introduced. A prototype for each gradient and Huygens’ metasurface is designed and simulated. To verify the designed structure, a Huygens’ metasurface prototype is fabricated using Rogers TMM 13i substrate. The measured results are in good agreement with the theoretical results

In this paper, a source reconstruction model (SRM) is proposed to correct and transform multi-planar magnetic near-field measurements. The correction algorithm provides a way to correct for linear amplitude and phase mismatch error between individual scans as practically this type of error is dominant for benchtop scanners. The algorithm is verified using simulated and measured test cases.

In this paper, a dual-band high-gain planar corrugated antenna is presented for applications in space and satellite communications. An analytic method based on the unit-cell analysis of a corrugated structure is presented to estimate the resonant frequency of the corrugated antenna where the maximum broadside gain happens. Therefore, the design of periodic corrugated antenna structures, which is very time-consuming due to the large size of the structure, is reduced to the design of a unit-cell of the structure which is very fast. A 2D corrugated (bull’s-eye) antenna structure is then parametrically studied to find the parameters which affect the resonant frequency of the corrugated structures. A dual-band bull’s-eye antenna with an integrated feeder structure at center is designed for the center frequencies of 9.7 GHz and 13.85 GHz. The dual-band operation is enabled using two different corrugations realized on two laminate boards. A prototype is fabricated and measured maximum broadside realized gains of 15. 8 and 17.5 dBi are achieved for the first and second bands, respectively.

A novel zero-power wireless sensor architecture is proposed and demonstrated in this paper. The proposed wireless sensor, which is a passive sensor, combines UHF RFID and a capacitive sensor to enable reading of physical and chemical parameters wirelessly, without compromising much on the read-range, and complexity of conventional RFID tags. The sensor alters the phase of backscattered RFID signal, which is detected at the receiver using a non-coherent IQ demodulator. Due to the universal nature of this architecture, any type of sensor, such as temperature, humidity, water level sensor, can be realized. For the sake of simplicity, a varactor diode was initially used to get a thorough understanding of the system. Following that, a flood sensor was used to evaluate the performance of zero-power wireless sensor in a real-world application.

In this paper, a simple approach to design and analyze corrugated antennas is proposed that estimates their general radiation performance. Based on the analysis of a unit-cell of the corrugated structure, the relationship between resonant frequency, spectral bandwidth, and directivity of the antenna is analytically derived. This simplifies the design of a corrugated antenna in terms of the design of a single cell of the corrugation. Hence, optimization process for designing corrugated antennas is made time efficient. The effect of corrugation width, height, as well as the permittivity of the material within the corrugations on the unit cell’s surface susceptance and antenna directivity is parametrically studied. Agreement is shown between the derived formulas for a unit-cell and the full-wave simulation of the entire antenna. The study of one unit cell of the corrugated antenna provides the substrate parameters for a desired band of operation. A 2D corrugated antenna with three corrugations is designed, and fabricated. The measured results show that a gain of 17.4 dBi can be achieved at the center frequency.