CPW fed active loop antenna for television receiver

The transistor amplifier integrated active dipole antenna offers advantages such as beam control, low noise and high gain. If the antenna and the amplifier are matched at a wider frequency bandwidth, the operating bandwidth of the active antenna will be extended. The authors have proposed a new type of active dipole antenna for television receivers. This antenna is fabricated on a thin dielectric film using photoetching techniques. Since a coplanar waveguide (CPW) consisting of a center strip with two ground planes located parallel to the strip is printed as a transmission line on the film a planar active antenna is realized. The CPW is located perpendicular to the dipole antenna. The silicon transistor amplifier is integrated between the feed point of the dipole and the CPW. Although the impedances between dipole and transistor amplifier are tolerably matched, the amplifier and the CPW are not matched. An active loop antenna for a television receiver is presented and its broadband operation is reported. In order to improve the impedance matching between the antenna, amplifier and the CPW at a wider frequency bandwidth, a deformed circular loop and a gallium arsenide field effect transistor (GaAs FET), the FHC30LG, are used as an antenna element and an amplifier, respectively. The input impedance characteristics, the receiving patterns and the actual gain are measured at Japanese TV channel frequencies from 90 to 770 MHz. >