Characteristics of digital terrestrial broadcasting antennas. (2) unbalance fed modified batwing antenna

The digital terrestrial broadcasting station will use multiple channels in common. Therefore, the required properties of the transmitting station will be broad bandwidth and high gain. The authors have previously (see IEEE AP-S Int. Symposium, p.1570-3, July 1999) investigated the 2-element modified batwing antenna with the reflector (2MBWAR) for UHF used in digital terrestrial broadcasting. It was calculated with the balanced feed shape. As a result, the broadband input impedance of 100 /spl Omega/ was obtained. However, in practical use, this antenna requires the balun and the impedance transformer as another circuit. So it has the complex feed system and high cost. In this paper, we propose the unbalance fed modified batwing antenna (UFMBA) which does not use a balun and an impedance matching circuit. The same broad bandwidth and high gain compared with the previous feed shape are obtained. Next, the parallel coupling UFMBA to obtain high gain is investigated. The gain of about 14 dBi is obtained for coupling four elements.