Jin-Taek Park

Compact Half Bow-tie-type Quasi-Yagi Antenna for Terrestrial DTV Reception

In this paper, we introduce a design method for a broadband planar quasi-Yagi antenna (QYA) for terrestrial digital television (DTV) reception. The coplanar strip line which feeds the driver dipole is connected to a microstrip line and is terminated by short circuit. By appending a wide strip-type rectangular director at a location close to the driver dipole, broadband impedance matching and gain enhancement in a high frequency region are obtained. The gain characteristics in a low frequency region are improved by adding a reflector formed by a truncated ground plane. To reduce the antenna size, the strip-type dipole and reflector are modified to half bow-tie (V)-shaped elements. The effects of various parameters on the antenna characteristics are examined. An antenna, as a design example for the proposed antenna, is designed for the operation in the frequency band of 470—806 MHz for terrestrial DTV. The optimized antenna is fabricated on an FR4 substrate and the experimental results show that the antenna has a good performance such as a frequency band of 450— 848 MHz for a VSWR 4.1 dBi, and front-to-back ratio > 10.4 dB.

BROADBAND SERIES-FED DIPOLE PAIR ANTENNA WITH PARASITIC STRIP PAIR DIRECTOR

A method to increase the bandwidth of a series-fed dipole pair (SDP) antenna by using a parasitic strip pair director is presented in this paper. A conventional SDP antenna consists of two dipole elements having difierent lengths and a ground re∞ector, which are serially connected with a transmission line. In the proposed antenna, a parasitic strip pair director is appended to the conventional SDP antenna. Initially, a conventional SDP antenna that operates in a frequency range of 1.7{2.7GHz is designed by optimizing the lengths of the elements (two dipoles and ground re∞ector) and the distances between these elements. Subsequently, a parasitic director containing a pair of strips is placed near the top dipole element to improve the bandwidth and gain of the conventional SDP antenna. Then, the efiects of the location and size of the director on the impedance bandwidth and realized gain are investigated. A prototype of the proposed antenna is fabricated on an FR4 substrate, and its performance is compared with that of the conventional SDP antenna. The experimental results show that the proposed antenna has an enhanced bandwidth of 1.63{2.97GHz (58.26%) and an increased gain of 5.6{6.8dBi.