High Gain Modified Dual-Band and Dual-Circularly Polarized Array Antenna

A novel design of double-layer dual-band circularly polarized array antennas (DDCPAAs) is presented in this paper. First, a DDCP single antenna is introduced as the array element. This element is composed of four truncated patches on the top layer and one other patch on the bottom layer. Then, with the aim of performance enhancement and extension of the antenna functionalities, 2 × 2 and 4 × 4 DDCPAAs are outlined. In the case of 2 × 2 structure, impedance bandwidth lies within 5.21–5.88 and 9.32–9.48 GHz. As well, it demonstrates CP characteristic within 5.24–5.86 and 9.32–9.46 GHz with gain values between 9 and 10.2 dBic. In the case of 4 × 4 DDCPAA, four 2 × 2 sub-arrays are implanted on the structure. In this configuration, the adjacent patches in neighboring sub-arrays are shared to decrease the elements spacing. Technically speaking, this feature suppresses the grating lobes, effectively. The proposed 4 × 4 DDCPAA exhibits an increased impedance bandwidth in two applicable frequency bands accommodating 5.05–6.01 and 9.16–9.98 GHz. Similarly, it improves the CP characteristics to attain a broader range namely 5.18–5.90 and 9.26–9.52 GHz. Moreover, gain values vary between 12 and 13.5 dBic. In both of DDCPAAs, feed network composed of two 3 dB/90-degree branch line coupler and a 3 dB/180-degree rat-race coupler is utilized. Detailed simulation studies extracted from Ansoft high frequency structure simulator are compared with that of measurement results to explore the efficiency of the proposed design. Results are discussed in depth.