Circularly‐polarised high gain cavity antenna based on sequentially rotated phase feeding

Abstract

A Fabry-Pérot cavity (FPC) array antenna providing both very high gain and circularly-polarised (CP) behaviour is proposed. To increase antenna gain and to obtain the CP characteristic, a superstrate is introduced above 2 × 2 feeding microstrip patch antennas (MPAs), which converts linearly-polarised (LP) incident waves to CP waves. Input phase difference between MPAs is designed to be exactly 90°to generate the high-quality CP characteristic in cooperation with the superstrate. By using the FPC, very high gain can be obtained with only a small number of feeders, which also provides another advantage of low mutual coupling among the neighbouring MPAs. Although the proposed antenna is very simple in its structure, it readily provides very high gain, high-quality CP property and very low axial ratio in a wide frequency range, which are great advantages compared with conventional CP antennas.Introduction: Various approaches have been proposed to improve the antenna gain and axial ratio (AR) of circularly-polarised (CP) antennas fed by single or multiple microstrip patch antennas (MPAs) [1][2][3][4][5]. A technique providing sequentially rotating phase values into each MPA has also been used to improve AR bandwidth, polarisation purity and symmetry in radiation patterns [2][3][4][5]. However, the conventional sequential rotation technique requires an array construction consisting of a large number of patch antennas, which increases not only the complexity in antenna design, but feed loss causing degradation of overall antenna efficiency.In this Letter, we present a high gain Fabry-Pérot cavity (FPC) antenna for a wireless local area network (WLAN) (5.15-5.35 GHz) application, which can radiate CP waves with a fairly low AR property. Compared with conventional CP array antennas, our antenna has some advantages such as high gain, simple feeding networks and excellent CP quality. By using an FPC technique, we can obtain very high gain with the help of only 2 × 2 arrays of simple linearly-polarised (LP) rectangular MPAs. Owing to a large separation distance among neighbouring antennas, the mutual coupling effect is much less than that in the conventional arrays. To verify our design approach, our theoretical prediction is compared with simulations using CST Microwave Studio. Good agreement between the predicted and measured data shows the validity and usefulness of our approach.

Coplanar Waveguide-Fed Bidirectional Same-Sense Circularly Polarized Metasurface-Based Antenna

“…Each patch on the back-to-back metasurfaces is shaped as a truncated corner square patch [22][23][24][25][26][27][28] to produce CP radiation. To obtain same-sense CP, the truncated patches on the bottom of the metasurfaces are rotated by 90° with respect to the trun- cated patches at the tops of the metasurfaces (to ensure they can be in opposite orientations).…”

High gain planar resonant cavity antennas based on metamaterial and frequency selective surfaces

“…Circularly polarized array antennas are placed as primary source in some of the previous research works [59,60]. Wide axial ratio bandwidth of RCA has been reported in the literature, where sequentially rotated phase feeding patch array antenna [61] is used as a primary source. Similarly, an attempt has been made to place aperture coupled CP source antennas underneath a FSS superstrate that supports circularly polarized radiation to enhance the overall axial ratio (<3 dB) bandwidth as well as impedance bandwidth of the RCA [62,63].…”

Wide-Band Dual Sense Circularly Polarized Resonant Cavity Antenna for X Band Applications

“…A smart solution to obtain high gain circularly polarized antennas is to use linearly polarized (or circularly polarized) planar antennas along with circular polarizers (or simple structures such as reflectors [2,3] and superstrates [4][5][6][7][8][9][10][11][12][13][14][15]). The antenna configuration consisting of partially reflecting superstrates placed over planar antenna is known as resonant cavity antenna (RCA).…”

“…Different topologies of wideband CP RCA have been reported in the literature [15,24]. In [15] by Ju et al, the PRS had been formed by using square patch arrays with a pair of truncated corners, and it was placed above a sequentially rotated patch antenna array. The configuration provided right-handed CP and 6.8% axial ratio bandwidth with maximum gain of 21.1 dBi at 5.2 GHz over 1 dB bandwidth of about 4%.…”