Comparative investigation of reflection and band gap properties of finite periodic wideband artificial magnetic conductor surfaces for microwave circuits applications in X-band

摘要

In this study, novel designs of artificial magnetic conductors (AMCs) for wideband operation are introduced. By using two techniques of the planar parasitic patches and stacked elements, AMC unit cells are achieved. The first design of the AMC unit cell is composed of four symmetric patches with two arms, which are coupled to a rhombic patch at the center. The second AMC design is configured of two stacked patches, which are connected together through the air spacing. The first and second AMC designs operate at the frequencies of 10.15 and 10.65 GHz with +/- 90 degrees reflection phase bandwidths of 8 to 12.38 GHz (43.15%) and 8 to 12.90 GHz (46%), respectively, for X-band operation. The proposed AMC unit cells present prominent features such as symmetric structures and wide bandwidths with distinct capabilities. To achieve an accurate evaluation of AMC performance, the reflection and band gap properties of the finite periodic AMC surfaces are investigated. The finite periodic arrays of the AMC reflectors are implemented and tested. The measured results show that they can be applied for wideband applications in microwave circuits and low profile antennas. The 15 x 15 AMC planar and stacked arrays under normal incidence operate at the frequencies of 9.89 and 10.25 GHz with the measured bandwidths of 7.85 to 12.02 GHz and 7.77 to 12.58 GHz, respectively. In addition, to identify the band gap properties of the finite periodic planar and stacked AMC arrays, the method of the suspended microstrip line is applied. For this purpose, the measured band gaps of the planar and stacked arrays include the ranges of 8.12 to 12.63 GHz and 7.81 to 12.10 GHz below -20 dB, respectively.