Active Phased Array of Cavity-Backed Slot Antennas With Modified Feeding Structure for the Applications of Direction-of-Arrival Estimation

This communication presents a cavity-backed slot antenna (CBSA) array for the estimation of direction of arrival (DOA). This new CBSA employs an alternative feeding structure to excite the radiation of cavity-backed slots and transfer the area for RF module implementation from the front surface of the array aperture to the bottom behind the cavity. This backfeeding design allows the accommodation of active RF modules inserted from the bottom behind the antenna aperture, and avoids interfering with the antenna radiation. The new feeding structure may also reduce the depth of the metal cavity and, in turn, decrease the thickness and weight of antennas in the phased array composition to make a compact array with a low profile. The bandwidth is found to be larger than that of a conventional CBSA. The antenna array for the DOA estimation has been prototyped with 32 elements. Experimental data and numerical simulation results are presented to validate the proposed antenna design concepts.