Circularly polarized strips integrated microstrip antenna for energy harvesting applications

Abstract

target was clear of clutter was used, thus removing the effect of clutter from the outdoor measurements. A first order multipath analysis was conducted and it was determined that the effects of multipath was negligible for this setup. The slight differences between the outdoor data and compact range data can be attributed to alignment inaccuracies of the tri-copter toward the radar, especially in elevation. A stabilizing gimbal can be attached to the tricopter as a mounting platform for the target or its antennas to reduce the fluctuations due to the roll, pitch and yaw of the tricopter. CONCLUSIONResults were presented for a relatively small and light weight cost effective airborne active calibration target, suitable for the calibration of a ground to air RCS measurement system. It was demonstrated that the calibration target had wide bandwidth and wide beamwidth properties. The static RCS characteristics of the airborne active calibration target were measured in a compact range and compared to outdoor measurements of the active calibration target mounted on a small remote controlled tricopter. The major advantages of the active calibration target are that it has a large beamwidth; is easy to deploy; is low cost as well as being wideband; and has a relatively large absolute RCS making it a suitable alternative over passive calibration targets for ground based radar systems. Another advantage of being airborne and in motion is that calibration measurements are out of ground clutter. This calibration system is also useful for independent verification of radar specifications by defence evaluation and research institutes. The airborne capability could also give the opportunity to verify the minimum detectable velocity of a target of a specified RCS. The RCS of the calibration target can be varied which could also be used to test deployed/ installed radar systems.ABSTRACT: A circularly polarized (CP) microstrip antenna with four strips is proposed for wide beamwidth and RF energy harvesting applications. Four strips along the diagonal directions are integrated symmetrically onto a square patch radiator for CP radiation with wide beamwidth. To improve the impedance matching of the antenna, a stub is integrated along the orthogonal direction of the patch radiator. The antenna is designed on FR4 substrate and an antenna prototype shows a measured 10-dB return loss bandwidth of 120 MHz (2.53-2.65 GHz) with a maximum gain of 4.6 dBic. The measured 3-dB axial ratio (AR) bandwidth is 65 MHz (2.540-2.605 GHz) with a 3-dB AR beamwidth of around 1808 across the band. Overall antenna volume is 0.475k o 3 0.475k o 3 0.013k o at 2.5 GHz.

A dual‐band antenna for extending cellular coverage by using energy‐harvesting strategy

“…The basis for the proposed design is a previous patch antenna prototype made for both energy harvesting and communication in the 2.5 GHz frequency band. The design consists of two pairs of half‐wavelength dipoles, a center patch, a stub located at the bottom of the centre patch and four connector patches.…”

“…However, their performance has matured considerably during the past 25 years, overcoming many of their limitations. Patch antennas using energy harvesting and communication in the same frequency band have already been described in the literature.…”

High diversity gain super‐wideband single band‐notch MIMO antenna for multiple wireless applications

“…A semi-crescent cascaded structure is also designed for good diversity performance with circular polarisation [33]. The circular polarisation antennas are beneficial for moving handhold or mobile communications like GPS which needs at least half power when the object is movable so the antenna is required below 3 dB axial ratio in a prescribed band [34]. The strip integrated circular polarised antenna is designed for radiofrequency energy harvesting application [35].…”

Single‐feed microstrip antenna for wide angle circular polarisation with six metal columns

“…Recently, circularly polarised (CP) antennas have received more and more attention and application, such as radio frequency identification, wireless local area networks, and global positioning system (GPS), in that it can reduce the polarisation loss on the moving carrier and reduce the multipath effect [1][2][3][4]. The microstrip antenna has become popular because of its simple structure, light weight, low profile, and easy realisation of various polarisations [5].…”