Anatoliy O. Boryssenko

Polarization Constraints in Dual-Polarized Phased Arrays Derived From an Infinite Current Sheet Model

Infinite current sheet radiator represents a phenomenological model of phased array antenna that exhibits formally simple but very general physics of array radiation. In this work, two superimposed, orthogonally directed infinite current sheet radiators are combined to synthesize arbitrary polarized scanned beams. The theory developed reveals principal physical constraints on polarization purity of this ideal phased array and indicates scan-adaptive amplitude and phase control conditions to mitigate polarization distortions as demonstrated for circular and slant linear polarization modes.

Antenna Link Transfer Function Factorization Applied to Optimized Channel Design

A channel broadband factored model is developed and numerically verified with a method of moment (MoM) technique for design of optimized UWB links with real, dispersive antennas. In this study, two-antenna link transfer functions are decomposed into port-load and full-wave dependent components based on general linearity and reciprocity in electromagnetics. Specifically, the port-related components account for antenna termination to the transmitter generator and front-end receiver circuits as antenna loads. In turn, the wave portion, which is associated with link transmission impedance, involves all geometrical factors like antenna shapes and their positioning/pointing in space that account collectively for radiation, propagation and reception. As a result, any link of fixed geometry can be full-wave numerically simulated just once for a suitable set of reference generator/load impedances. Then, all variations in link performance caused by variable port terminations are easily predicted by manipulating the full-wave data obtained for the case of reference antenna port loads. This approach provides some useful physical insights and an optimized co-design procedure for transmitter and receiver impedances to meet several significant performance-related design objectives, such as: i) maximized link energy transmission efficiency; ii) maximum amplitude of received signals; iii) minimized time confinement for signal energy at receiver loads; iv) flatness of magnitude of link transfer functions; and v) minimized group delay deviation. The major results are numerically illustrated for a number of useful far-field line-of-sight link cases with flat and solid dipole antennas operating in up to 3:1 bands and ideally aligned in terms of their gain and polarization matching. Numerical results are given in a normalized form and scalable to any band of interest

Packaging of Dual-Mode Wireless Communication Module Using RF/Optoelectronic Devices With Shared Functional Components

This paper reports the design, fabrication, and testing of a compact radio-frequency (RF)/ free space optical (FSO) dual mode wireless communication system. A modified split dual-director quasi-Yagi antenna is integrated with optical transmitter and receiver by sharing layout structural components. Bare die vertical-cavity surface-emitting laser (VCSEL) and P-i-N photodiode (PIN) are placed on antenna director pads and wire bonded to printed circuit board (PCB)-mounted laser driver and transimpedance amplifier (TIA) circuits. Detailed analysis of coupling between RF channel and associated electrical connections for the FSO channel is presented using commercial simulation tools to predict its impact on link degradation. Although crosstalk appears between RF and optical channels, the prototyped system demonstrated dual-mode high-rate communication capability with measured 2.5 Gb/s data rate in FSO link. Variations in RF subsystem features due to coupling from the FSO subsystem is estimated through radiation pattern measurement using near-field scanner.

UWB radar imaging system with two-element receiving array antenna

UWB signals can propagate in cluttered environment and opaque media that enables exploring hidden homogeneities through registering and processing backscattered signals. One of such an application is UWB through-wall vision radar (UWBR), Sostanovsky (2004), Radar Vision (2005). A prototype of low-complexity and low-cost portable UWBR sensor with a small receiving antenna array is presented. Several key implementation issues are discussed including design of antennas and other electromagnetic-related aspects of signal processing algorithms for time-domain focusing and imaging. Simulated and measured radar images demonstrate radar operation to map out a person behind walls.

Wave propagation and coupling in linear arrays with application to the analysis of large arrays

Waves inside linear arrays are analyzed for the case of single port excitation. A frequency-domain method is proposed for the extraction of the amplitude decay and phase velocity of the waves, based on simulation results obtained for terminal excitation at one end and near the middle of the array. The waves reflected by the array ends are also extracted, under a single-reflection assumption. This model is then exploited for estimating the port currents when other elements of the array are excited, as well as for larger arrays. Simulation results are shown for port currents and element patterns in arrays of broad-plate dipoles.

Time-Domain Integral-Equation-Based Solver For Transient And Broadband Problems In Electromagnetics

A time-domain (TD) numerical method has been developed based on the method-of moments (MoM) and marching-on-time (MoT) solution of the electrical-type integral equation with mixed potential formulation and free-space Green’s functions. This timedomain integral-equation (TDIE) code is applicable for arbitrary 3-D antennas and arrays composed of conductors. It was developed particularly to simulate ultra-wideband (UWB), finite phased arrays of tapered slot antennas and some results from this study are included in the paper. The TDIE, which calculates wideband data in a single solution and utilizes basis functions defined only on the surfaces of conductors but not throughout the entire volume of the array, requires much less RAM and CPU time than frequencydomain and FDTD methods.

Ultra-Wide Band Near-Field Imaging System

An experimental ultra-wideband radar system prototype is presented for imaging objects located in the near field of the radar antennas. The system is primarily intended for through-matter, e.g. through-wall, target detection and imaging. The radar hardware is based on several novel technical solutions in the design of its electromagnetic (EM) and circuit components including a new antenna element with wide impedance and gain bandwidth. The same elements are employed for the transmit channel and the two-element receive array. The signal processing and target imaging algorithms are presented. Some results of indoor tests to image in 2-D the spatial position of a cylindrical object are reported. In particular, a brightest-spot recognition technique is demonstrated that uses a number of special radar calibration routines to set properly the time/range scale required for precise target localization and imaging while avoiding appearance of false target responses.

A wave-based model for mutual coupling and truncation in finite tapered-slot phased arrays

The tapered-slot (Vivaldi) endfire element is a promising candidate for broadband phased arrays. These arrays often are designed by using estimates from infinite arrays and ignoring edge effects arising from truncation of the infinite periodic array. However, the strong mutual coupling that contributes to wide bandwidth performance often leads to severe truncation effects within the finite Vivaldi array. This study presents a time-domain approach to coupling and truncation phenomena with the help of; (1) full-wave numerical simulation and (2) wave-based physical modeling. First, the full-wave solution provides the terminal currents for all elements in the finite array. Next, the coupling and truncation effects are modeled by waves propagating across the aperture. Time gating of the computed terminal currents enables decomposition of the wave events. The dispersion characteristics of the waves propagating across the aperture can be quantified and edge reflection coefficients can be estimated. This process provides physical insight to better understand the behavior of finite Vivaldi arrays.

Optimized Ultra-Wideband Radiation of Dipole Antennas With Triangle Driving Pulses

This paper addresses optimization of transient radiation from dipole antennas in terms of minimized pulse extent in time or flat power spectral density. The former is a typical requirement for high-range-resolution radars while the latter can meet the Federal Communication Commission (FCC) regulations on spectrum usage. Recent needs and advances in ultra-wideband (UWB) signal processing, target identification, remote and subsurface sensing, reach-frequency tagging, secure communication, and others stimulate a variety of diverse studies in transient and broadband electromagnetics, including pulsed antennas. These generic problems have been widely explored through full-wave numerical analysis, theoretical and asymptotic approaches, nonlinear optimization methods combined with full-wave electromagnetic solvers, the E- and K-pulse signal processing techniques, and other fashions.

Analysis of infinite and finite arrays of tapered-slot antennas for SKA

Broadband phased arrays are a potential technological solution for the Square Kilometer Array (SKA) radio telescope. The analysis of such arrays, and the determination of the effects of array truncation can be done either in the frequency domain, by element-by-element, infinite-array, or finite-by-infinite array approaches, or in the time domain, using an integral equation formulation. In this paper, the two techniques are compared in the case of a moderate-size array made of Vivaldi elements, whose dimensions are the same as those used for the THEA (Thousand Elements Array) demonstrator.