Broadband linearly/circularly polarized microstrip filtering antennas

Abstract

Two linearly and circularly polarized filtering antennas with low profile, broad bandwidth, and improved gain are proposed. Without increasing the antenna profile, a vertically coupled resonant structure, which can broaden the bandwidth and provide the filtering response, is employed. To prove the concept, a broadband linearly polarized (LP) filtering antenna is designed by integrating the hairpin resonator on the feed, U‐slot resonator in the ground and the patch resonator. Then, we design a broadband circularly polarized (CP) filtering antenna, which utilizes a single‐feed dual‐coupled structure for two coupling routes with 90° phase difference to excite two orthogonal resonant modes without power divider and phase delay line. Both antennas exhibit third‐order filtering characteristics with improved bandwidths and flat in‐band gain. The equivalent circuits of both antennas are discussed. The LP and CP antennas achieve an impedance band of 28% and 29.6%, respectively. The CP antenna shows a 3‐dB axial ratio bandwidth of 17.6%. Both antennas also exhibit the high gain of 9.5 dBic with less than 0.6 dB variation within the band.

Double‐layer metasurface‐based low profile broadband X‐band microstrip antenna

“…Circularly polarised patch antennaes have always experienced narrow axial-ratio bandwidth. As tabulated in Table 1, techniques such as sequential-phase feed [23][24][25], U-shaped groove [8,26] and their combinations were utilised as conventional solutions in order to attain wide axial-ratio bandwidth. However, the expansion effect and high profile are still inadequate for applications with high-performance requirements, and the sequential-phase feed is only applicable in developing the antenna array.…”

“…Kidder et al [7] introduced a compensation capacitor by etching a U-shaped groove in the radiation patch and obtained an impedance matching bandwidth of 21.5% under the excitation of a proximity-coupled double Π-shaped feed line. A particular study [8] etched the Ushaped groove onto the ground plane, and the single-fed dualcoupled circularly polarised antenna finally realised a 29.6% impedance matching bandwidth (S11 ≤ − 10 dB) and 17.6% axialratio bandwidth (axial ratio≤ 3 dB). However, the aforementioned designs are only feasible when the thickness of the medium is about 0.1λ 0 , where even an air cavity is required for its operation.…”

Compact dual‐band circularly polarized filtering patch antenna using dispersive delay line

“…During the codesign of CP filtering patch antenna, it is very challenging and pretty meaningful to achieve outstanding antenna performance. In fact, some attempts have been made so far on the design of CP filtering antenna in a few recent papers [3][4][5][6][7][8][9] . The CP filtering antennas were realized by suspending the patch radiator above the filtering network [3][4][5][6][7] , which was mainly composed of coupled stripline open-loop resonators.…”

“…In fact, some attempts have been made so far on the design of CP filtering antenna in a few recent papers [3][4][5][6][7][8][9] . The CP filtering antennas were realized by suspending the patch radiator above the filtering network [3][4][5][6][7] , which was mainly composed of coupled stripline open-loop resonators. Moreover, wideband CP dielectric resonator antenna (DRA) 8 was proposed, and the filtering response was primarily produced by the codesign of wideband filtering quadrature couplers and a snowflakeshaped patch.…”

A single‐layer filtering patch antenna array with simple differential feeding network

“…In order to reduce the volume of radio‐frequency system and decrease the complexity of the design, it is an effective approach to integrate the filtering performance to the antenna. A co‐design that incorporates the antenna and the filter is proposed 3‐12 . The third square open‐loop resonator of the filter is designed as a radiator to achieve a filtering antenna 3 .…”