Beam width expansion of microstrip array antenna by wide angle impedance matching layer

In this paper, a new method for calculation the active reflection coefficient of an array antenna has been proposed, and accordingly an anisotropic wide angle impedance matching layer has been designed to mitigate blind spots. The designed antenna consists of a microstrip array with rectangular arrangement. The space between the elements in the mentioned array is equal with 0.63 wavelength in X band. In order to compensate the impedance mismatch near the blind spots between the antenna and the free space above the aperture and also to increase the antenna scan range, the anisotropic matching layer characteristics are extracted by genetic algorithm optimization method. Finally, its efficiency is investigated in CST Microwave Studio and HFSS software. Compared with other similar techniques, the proposed method is simpler, faster, and does not require to fabricate and coupling coefficients measurement. It is a powerful tool for deriving the active reflection of microstrip array antenna that is difficult to extract their analytical equations. The designed wide-angle impedance matching layer has increased the scan range of antenna from ±34° to ±42° by shifting blind spots.