Bandwidth Enhancement of Circularly Polarized Square Slot Antenna

Abstract

Abstract-Bandwidth enhancement technique of circularly polarized square slot antenna is presented in this paper. A square slot antenna with the components of L-probe separated could achieve an axial ratio (AR) bandwidth of 33.84%. Placing Stubs in the slot by studying the electric field behaviour could enhance the AR bandwidth by around 10%. Creating an L-shaped slot on the ground plane, where the electric field rotates in the desired clockwise direction, can further enhance the bandwidth by 7%. A < −10 dB S 11 bandwidth of 46.15% and < 3 dB AR bandwidth of 50.35% could be achieved with the present design. Unidirectional patters are obtained by having a cavity at the wide slot of the antenna and shows a measured bandwidth of 41.79% in S 11 and 44.97% in AR. Both antennas show a cross polarization discrimination of more than 15 dB on a wide azimuth range. The measured results well comply with the simulated results.

Design of Broadband Circularly Polarized Square Slot Antenna With a Compact Size

“…From the CP antennas proposed in [13][14][15][16][17][18], we notice that if the feeding signal line of a PSSA is of L or inverted-L shape, CP radiation can be excited in a certain frequency band. Our CP PSSA design starts with this design concept.…”

“…Note that most CP antennas in [13][14][15][16][17][18][19][20][21][22] are designed to operate in S band (2-4 GHz). For comparison with those antennas in terms of antenna gains and ARBWs, the antenna design procedures to be developed in this study will also use an S-band CP PSSA as an example.…”

“…In addition, their normalized slot areas are larger than 0.1λ 2 L . The antenna designs in [16,17] with an L-shaped coupled feedline and embedded stub(s) in the slot regions have smaller antenna areas than those in [13][14][15] while still having large slot areas.…”

“…Many popular circularly polarized (CP) patch antennas [3][4][5][6][7] and loop antennas [8,9] have narrower CP bandwidths of less than 20%. Known not only for their compactness and low-profile features but also for their easily attained large CP bandwidths using simple design technologies and constructions, printed slot antennas have received much attention in recent years [10][11][12][13][14][15][16][17][18][19][20][21][22]. Among these antenna designs, the CP ring slot antennas in [10][11][12] still have CP bandwidths of less than 25% even though many CP-bandwidthenhancement efforts have been made.…”

TRANSPARENT ANTENNA DESIGN FOR WiMAX APPLICATION

“…These films are indium tin oxide (ITO), fluorine-doped tin oxide (FTO) and silver coated polyester film (AgHT) [7]. A number of slot shapes were introduced to enhance the antenna BW, particularly in monopole antenna designs such as Π-shaped slot [ [13], square slot [14], step-slot antenna [15], a compact split-ring slot with EBG [16], SIW slot [17] and slotted ground structure [18]. As the proposed transparent antenna is manually made by cutting out the patch and the feed from the coated polyester sheet of AgHT-4, a simple shape of planar monopole antenna is preferred and a wide bandwidth (BW) can be obtained by properly designing a suitable arc shaped slot on the ground plane.…”