Directivity and bandwidth of single-band and double-band yagi arrays

The purpose of the communication is to obtain the optimum design of a Yagi array under constraints on bandwidth, directivity, or the size of the array. It is shown that the array configuration is determined if any two of these constraints are specified. The present study also shows that a properly designed Yagi array can be operated at two frequency bands with the frequency ratio approximately equal to 3.5.