Design method of Yagi-Uda two-stacked circular loop array antennas

A design method which works as a single balanced feed antenna is presented for the Yagi-Uda two-stacked circular-loop array antenna. The antenna is analyzed with a theoretical model consisting of loop elements and feeder sections. The results are compared with experiments. By using the computed and measured antenna currents, the gain enhancement of the antenna is confirmed to be due to both the stacked-loop-array and endfire-array effects. A method of compensation for the reflection loss and a design procedure are discussed in detail. A graphical method is given to estimate the optimum size of the antenna without detailed numerical calculations, and the performance of the designed antenna is demonstrated by experiments. Experimental results are presented for several antennas arranged with different numbers of loops in the endfire and broadside directions