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Novel designs of a circularly polarized 2 × 2 and 4 × 4 slot array antennas (CPSAAs) are proposed. Sequential phase feed network composed of a section of 270° and four strips is utilized to feed the array structures. Array elements are simple linearly polarized wide slot antennas (WSAs) composed of simple radiating patches with truncation on four corners and slotted ground plane on substrate backside. Each WSA operates over the UWB frequency band of 3.1–10.6 GHz. When the WSAs are arranged in the form of 2 × 2 and 4 × 4 CPSAAs, frequency bands of 3–13.1 and 1.4–12.3 GHz are covered, respectively. More importantly, CP is generated at 4.5–8 and 4.6–8.8 GHz for 2 × 2 and 4 × 4 CPSAAs, respectively. This is while; the WSAs are linearly polarized elements. Higher gain values and wider bandwidths are obtained with respect to single WSA. Design process and performance analysis of the single and array antennas are discussed through the paper.

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This paper outlines an efficient design of a wideband sequential-phase (SP) fed circularly polarized corner-truncated patch array antenna (CPCTPAA) with sequentially rotated (SR) array elements. The SP feed network is composed of a circular ring with an inner section of 270°. Four shorting strips are attached to the circular ring to the end of which corner-truncated patches (CTPs) are attached. Through the proposed feed structure, stable phase difference is attained at the end of the shorting strips which in turn ends in CP generation. Each array element of 2×2 CPCTPAA is a CTP printed on the top side of the FR4 substrate. On the backside, rectangular slots are removed from the ground plane to enhance the bandwidth characteristics of the proposed design. Moreover, suitable rectangular slots are embedded at the crossing points of CTPs and feed lines which instigate extra improvements in CPCTPAA performance. These amendments, all together, are deemed for achieving an efficient and cost-effective CPCTPAA design with smaller occupied implementation space. Simulation and experimental studies are conducted on a 70×70×1.6 mm 3 prototype to evaluate performance of the proposed array antenna. Results are discussed in depth.

Abstract. A novel and compact design of a circularly po-

Compact broadband circularly polarized elliptical slot antenna arrays (CPESAAs) are devised based on 2 × 2 and 4 × 4 circularly polarized (CP) elliptical slot antennas and a sequential phase feed network. To realize the circular polarization, eight rectangular stubs are embedded in the feed structure to excite two orthogonal E vectors in 2 × 2 CPESAA configuration. Moreover, by taking four rectangular slots out from each array element, return loss and axial-ratio bandwidths are noticeably increased. The investigated simple array element has a compact size of 20 × 20 × 1 mm3. As well, 2 × 2 CPESAA occupies a compact size of 55 × 60 × 1 mm3, which operates within the frequency band 4.18–9.35 GHz. Thus, 76.4% of S11< −10 dB and 51.4% of CP bandwidth (4.43–7.5 GHz) are covered. Moreover, proposed 4 × 4 CPESAA is printed on 110 × 110 × 1 mm3FR4 substrate and covers the frequency band of 1.15–12.98 GHz with CP at 2.95–8.82 GHz. Throughout the study, the design process of the proposed antenna arrays are presented and discussed in detail.