Small-sized Planar Spiral Monopole Antennas by Using Parasitic Elements

In this paper, a small-sized planar square-spiral monopole antenna is proposed by using parasitic elements. The Parasitic element is composed of a crossed strip and additional right-angle folded(L-type) stirps. And these parasitic elements are printed on a substrate which is the opposite side of a radiation element . When the parasitic elements are used, the size of the square-spiral monopole antenna is reduced by for the same operating frequency compared to the antenna without parasitic elements. The radiation pattern of the proposed antenna is nearly omni-directional in azimuth. The designed antenna can be used in the application of channel 12 digital mulimedia broadcasting(DMB) handset.