Broadband CPW-Fed Circularly Polarized Square Slot Antenna With Three Inverted-L-Shape Grounded Strips

Abstract

A new form CPW-fed broadband circularly polarized square slot antenna (CPSSA) with three inverted-L-shape grounded strips around the corners of the slot is proposed and fabricated. In comparison to the previous CPSSA structures, the axial-ratio (AR) bandwidth of the antenna is increased, which is two times wider than the previous proposed design. By embedding the L-shape strip to the ground plane and using the vertical stub to the feed line, very good axial-ratio bandwidth is obtained. The measured impedance bandwidth and AR of the realized CPSS antenna with optimized parameters is from 2 to 7 GHz (3.5:1, 110%) for VSWR 2 and 2-5 GHz (2.5:1; 85%) for AR 3 dB respectively. Throughout this letter, the improvement process of the AR and 11 properties is completely presented and discussed.Index Terms-Axial ratio (AR), broadband, circularly polarized (CP), square slot antenna.

Broadband Circularly Polarized Cross Shaped Slot Antenna With an Improved Feedline

“…The use of circularly polarized (CP) antennas [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] has gained much momentum in the wireless engineering community due to their ability to suppress multipath fading and doing away with the need for arranging the orientation of transmit and receive antennas. Also, CP antennas provide better mobility and immunity to adverse weather conditions than linearly polarized antennas.…”

“…Such perturbations include introducing RF switch controlled rectangular discontinuities on patches [4]; using a feeding mechanism made up of a hook shaped feed line and Γ-shaped slots in a patch antenna [5]; employing cross shaped slots in patch antennas [6,7]; adding stubs and notches to square slots [8]; inserting grounded inverted L strips in the radiating slots of slot antennas [9,10]; using a lightening shaped feedline [11,12]; using an L-slot in place of the traditional rectangular, circular or square slot of a slot antenna [13,14]; improving the ground plane by adding stubs to it or creating slots in it [15][16][17][18][19] or by embedding a pair of hat shaped patches in an annular ring slot and employing a deformed feedline [20]. However, most of the existing antennas posses large sizes or narrow axial ratio bandwidths (ARBW) that do not cover enough wireless applications.…”

CPW-Fed Circularly Polarized Square Slot Antenna With Enhanced Bandwidth and Reduced Size for Wideband Wireless Applications

“…Coplanar waveguide-fed circularly polarized slot antennas have attracted great attention due to their merits of simple structure, low profile, light weight, low fabrication cost, broad bandwidth, capabilities of reducing polarization mismatch, suppressing multipath interferences, and suitability for integration with microwave circuits [1][2][3][4][5][6][7][8][9][10]. Meanwhile, since the feature of broad 3-dB axial ratio (AR) bandwidth is becoming increasingly necessary due to the high data rate and multimedia required by modern services, many newly published techniques in [6][7][8][9][10] focus on the realization of broad circular polarization (CP) bandwidth with various coplanar waveguide-fed (CPW-fed) circularly polarized square slot antenna structures.…”

“…Meanwhile, since the feature of broad 3-dB axial ratio (AR) bandwidth is becoming increasingly necessary due to the high data rate and multimedia required by modern services, many newly published techniques in [6][7][8][9][10] focus on the realization of broad circular polarization (CP) bandwidth with various coplanar waveguide-fed (CPW-fed) circularly polarized square slot antenna structures. In [6], by protruding a symmetric T-type strip from the CPW feedline and introducing a nesting-L slot structure in the ground, the CP antenna produces a CP bandwidth of 60.9%.…”

“…Moreover, a check-shaped strip with its vertex connected to the protruded strip of the CPW is used to achieve a wide CP bandwidth of 48% in [9]. In addition, by adding three inverted L-shaped strips around the corners of the square slot, the antenna proposed in [10] obtains a CP bandwidth of 85.7%, whereas its size is not compact.…”