Single Polarization Antenna Research Articles

Spatial Processing Using High-Fidelity Models of Dual-Polarization Antenna Elements

This paper generalizes a recent improvement to a traditional spatial-processing algorithm to optimally use body-mounted arrays of dual-polarization radio-frequency antenna elements rather than single-polarization antenna elements. The paper’s generalized algorithm exploits high-fidelity far-field gain and polarization data, generated most practically by a computational electromagnetic solver (CES), to characterize the antenna array’s individual dual-polarization elements. Using this characterization and that of the desired and undesired communication nodes’ antennas, the generalized algorithm determines the array’s optimal weights. The subsequent application of a CES to a practical scenario, in which an optimally weighted array of dual-polarization antenna elements is mounted on a representative body, demonstrates the generalized algorithm’s exceptional spatial-processing performance.

A Digital Beamformer for the PHAROS2 Phased Array Feed

PHased Arrays for Reflector Observing Systems (PHAROS) is a C-band (4–8[Formula: see text]GHz) Phased Array Feed (PAF) receiver designed to operate from the primary focus of a large single-dish radio astronomy antenna. It consists of an array of 220-element Vivaldi antennas ([Formula: see text] polarization), cryogenically cooled at roughly 20[Formula: see text]K along with low noise amplifiers (LNAs), and of analogue beamformers cryogenically cooled at roughly 80[Formula: see text]K. PHAROS2, the upgrade of PHAROS, is a PAF demonstrator developed in the framework of the Square Kilometer Array Advanced Instrumentation Program (SKA AIP) with the goal of investigating the potential of the PAF technologies at high frequencies in view of their possible application on the SKA dish telescopes. The PHAROS2 design includes new cryogenically cooled LNAs with state-of-the-art performance, a digital beamformer capable of synthesizing four beams from a sub-array of 24 single-polarization antenna elements, and a C-band multi-channel Warm Section receiver capable of analogue filtering and down-converting the signals from the antennas to a suitable frequency range at the input of the digital backend, providing an instantaneous bandwidth of 275[Formula: see text]MHz for each signal. In this paper, we describe the design and performance of the PHAROS2 digital backend/beamformer, based on the Italian Tile Processing Module (ITPM) hardware, which was initially developed for the SKA Low Frequency Aperture Array (LFAA). The backend was adapted to perform the beamforming for our PAF application. We describe the implementation of the beamformer on the Field Programmable Gate Arrays (FPGAs) of the ITPM and how the backend was successfully used to synthesize four independent beams, both in the laboratory (across the entire 275[Formula: see text]MHz instantaneous bandwidth) and during on-field observations at the BEST-2 array (across 16[Formula: see text]MHz instantaneous bandwidth), which is a subset of the Northern Cross Radio Telescope (located in the district of Bologna, Italy). The beamformer design allows re-scaling to a greater number of beams and wider bandwidths.

Mitigating Multipath Bias Using a Dual-Polarization Antenna: Theoretical Performance, Algorithm Design, and Simulation.

It is well known that multipath effect remains a dominant error source that affects the positioning accuracy of Global Navigation Satellite System (GNSS) receivers. Significant efforts have been made by researchers and receiver manufacturers to mitigate multipath error in the past decades. Recently, a multipath mitigation technique using dual-polarization antennas has become a research hotspot for it provides another degree of freedom to distinguish the line-of-sight (LOS) signal from the LOS and multipath composite signal without extensively increasing the complexity of the receiver. Numbers of multipath mitigation techniques using dual-polarization antennas have been proposed and all of them report performance improvement over the single-polarization methods. However, due to the unpredictability of multipath, multipath mitigation techniques based on dual-polarization are not always effective while few studies discuss the condition under which the multipath mitigation using a dual-polarization antenna can outperform that using a single-polarization antenna, which is a fundamental question for dual-polarization multipath mitigation (DPMM) and the design of multipath mitigation algorithms. In this paper we analyze the characteristics of the signal received by a dual-polarization antenna and use the maximum likelihood estimation (MLE) to assess the theoretical performance of DPMM in different received signal cases. Based on the assessment we answer this fundamental question and find the dual-polarization antenna’s capability in mitigating short delay multipath—the most challenging one among all types of multipath for the majority of the multipath mitigation techniques. Considering these effective conditions, we propose a dual-polarization sequential iterative maximum likelihood estimation (DP-SIMLE) algorithm for DPMM. The simulation results verify our theory and show superior performance of the proposed DP-SIMLE algorithm over the traditional one using only an RHCP antenna.

Design and experimental investigation of stripline antennas

The results of development and experimental investigation of several centimeter-wave planar antennas are presented. The antennas contain a multichannel stripline power divider and a 2D periodic array of slot radiators excited by symmetric strip lines. A single-polarization antenna, an antenna with two linear polarizations, and an antenna with two circular polarizations are analyzed. The results of measuring the basic parameters of these antennas (the gain, the radiation pattern, and the cross-polarization level) are presented. Specific features of the design of such antennas and possible means of improvement of their performance characteristics are discussed.

Wide-band photonically phased array antenna using vector sum phase shifting approach

In this paper, a wide-band photonically phased array antenna is demonstrated. The array configuration consists of a 4 /spl times/ 1 Vivaldi single-polarization antenna array and an independent photonic phasing system for each element. The phasing network of this array is implemented using two novel photonic phase shifters based on the vector summation approach. A vector sum phase shifter (VSPS), which exhibits a frequency-linear characteristic from dc to 15 GHz and can be continuously tuned from 0 to 100/spl deg/, is presented. A second-order VSPS (SO-VSPS), a modification of the VSPS that is capable of 0-430/spl deg/ phasing range, is also demonstrated. This paper presents the operation and characterization of each component of the array, including the radiating elements and the various photonic phase shifters and, finally, a demonstration of the combined system. A discussion on the practicality of this system for airborne applications is presented, along with suggestions for simplification and improvement.