Compact Microstrip-Fed Square Loop Antenna for DTV Applications

A design method for a compact square loop antenna fed by a microstrip (MS) line for indoor digital television (DTV) applications is proposed. The proposed antenna consists of a square loop, circular sectors, and an MS line. The square loop combined with circular sectors is printed on one side of a substrate, and a 75-Ω MS line is printed on the other side. The circular sectors are used as a wideband balun or transition to connect the MS line and the square loop. A prototype of the proposed square loop antenna operating in the DTV band (470–806 MHz) is designed and fabricated on an FR4 substrate. Experimental results show that the proposed antenna has the desired impedance characteristics in the frequency band of 464–1,220 MHz (89.8%) for a voltage standing wave ratio (VSWR) of <2 covering the DTV band, and a broadside gain of 0.8–3.3 dBi in the DTV band.