Scanning Angle Extension of a Millimeter-Wave Antenna Array Using Electromagnetic Band Gap Ground

A compact phased array with extended beam steering characteristics for the millimeter-waveband of the fifth-generation (5G) applications is presented in this communication. An E-shaped patch antenna placed on an electromagnetic bandgap ground (EBGG) with operating bandwidth of 24.2-27.5 GHz is used as the basic building block of the eight-element linear array. The array utilizes both the in-phase reflection characteristic for broad element radiation pattern and the bandgap characteristic for mutual coupling reduction for limited inter-element spacing of the proposed array. The existence of the EBGG enables a compact array with the inter-element spacing of around 0.4 wavelengths at the center frequency, yet the isolation between each element is still above 17 dB within the whole band of interest, which also helps to increase the array directivity at large scanning angles. The scanning angle of the array with the electromagnetic bandgap (EBG) structure ranges from -75° to 75° at 26 GHz within 3 dB scanning loss. The proposed EBGG extends the antenna array's spatial coverage and enables a compact size of the array, which is very attractive for 5G millimeter-wave (mm-wave) application.