A Compact, Wideband, Dual Polarized CPW-Fed Asymmetric Slot Antenna for Wireless Systems

Abstract

Wideband, dual sense circularly polarized (CP), asymmetric circular slot fed by coplanar waveguide is proposed and designed. Dual polarizations are obtained by using a horizontal stub to the feed line and embedding the L-shaped strip onto the slotted ground plane. The simulated result of impedance bandwidth shows wideband performance is produced by four resonant modes. Some key parameters are studied to analyze the characteristics of the proposed antenna. The overall volume of the proposed antenna is 18 mm × 18 mm × 1.6 mm. The measured value of 10 dB impedance bandwidth is 112%at frequencies from 4.2 GHz to 14.9 GHz with voltage standing wave ratio (VSWR) ≤ 2. The 3-dB axial ratio bandwidths are 39.3% for the lower band which senses righthand circular polarization (RHCP) and 2.8% for the upper band which senses left-hand circular polarization (LHCP) relative to the center frequency of 6.1GHz and 14.1 GHz, respectively. The proposed structure gives a good radiation pattern with moderate gain. Index Termsasymmetric slot antenna, circular polarization, CPW feed, wideband antenna. I. INTRODUCTION The microstrip patch antenna is a new kind of radiator, which is compatible with integrated circuit technology and offers advantages such as thin profile, light weight, low price, and conformability to a shaped surface. It is usually designed for single-mode linearly polarized (LP) operation that radiates only horizontally or vertically polarized waves [1]. To overcome this limitation, a multi-band CP antenna is needed. It is used to make independent data transmission and reception from the orientation of the transmitter and receiver and remove the multipath shortcomings. For CP radiation, a patch should support two orthogonal modes of the same amplitude however, 90 o phase difference. To achieve these modes a single patch with appropriate excitations or a properly structured array of patches with proper phasing is required. Using a printed slot antenna with coplanar waveguide (CPW) feed is one of the methods to prevent the increasing size of the antenna and improve the operating bandwidth. The main features of CPW feed are wider bandwidth, a single metallic layer, easily

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