Microstrip Antenna Arrays Fed by a Series-Parallel Slot-Coupled Feeding Network

A novel concept of a feeding network of a microstrip antenna array composed of series-fed linear subarrays has been shown. The proposed feeding network utilizes a concept of a slot coupler, in which two microstrip lines are coupled through a slot in a common ground plane. As it has been shown, such a slot coupler provides equal-amplitude and out-of-phase output signals and, therefore, can be used for appropriate feeding (at the center) of a single linear antenna subarray that utilizes “through-element” series-feeding technique. The proposed concept of a slot coupler has been used for the design of an 8 × 8 antenna array, in which all 8 × 1 linear subarrays are series-fed, whereas all 8 linear subarrays are fed by a parallel feeding network.