Backfire antennas constructed with coaxial circular loops

The radiation characteristics of backfire antennas constructed entirely of circular loops are studied. A comparison between this type of backfire antenna and the conventional one, made of a solid reflector, reveals that the optimum dimensions of the reflector and the peripheral rim are approximately the same for both kinds of antennas. In addition, it is found that as few as six loops are sufficient to construct the optimum reflector, and almost the same number of loops are required to form the optimum peripheral rim. The new structure reduces the weight, windage, and obstruction of view which accompany solid reflectors. In addition, the new antenna lends itself to exact analytical investigation.