Coupled Yagi arrays

The purpose of this study is to obtain the optimum design of a three-row Yagi array antenna under constraints on bandwidth, directivity, or the length of the array. It is shown that the array configuration is determined if any two of these contraints are specified. It is also shown that a properly designed coupled Yagi array can be operated at certain frequency band with higher directivity and wider frequency bandwidth than those of a single-row Yagi array.