Title :
Low power repeater station of medium frequency broadcasting antennas
Author :
Kawakami, H. ; Sato, G.
Author_Institution :
Fac. of Sci. & Technol., Sophia Univ., Tokyo, Japan
Abstract :
The resonance frequency of a modified umbrella antenna with a top ring is shown to be lower than that of an umbrella antenna, and the real part of the input impedance of the former takes large values in a frequency range higher than a certain frequency. Also, the longer the stay length, the lower the resonant frequency. The longer the top radius, the greater the real part of the input impedance, but the design strength is degraded by the incremental radius. The input impedance of a spiral umbrella antenna was investigated, and improvement of its efficiency of 2 to 3% can be expected. If the design frequency is considered to be close to 1500 kHz, a spiral umbrella antenna, having a top radius within the permissible limits of installation technology and attached with stays whose lengths are appropriate, can be considered to be practical.<>
Keywords :
broadcast antennas; electric impedance; radio broadcasting; radio stations; repeaters; 1500 kHz; MF; efficiency; frequency range; input impedance; low power repeater station; medium frequency broadcasting antennas; radio broadcasting; radio stations; resonant frequency; spiral umbrella antenna; stay length; top radius; top ring; Antenna measurements; Antenna theory; Arm; Directive antennas; Frequency; Impedance measurement; Poles and towers; Radio broadcasting; Repeaters; Spirals;
Conference_Titel :
Antennas and Propagation Society International Symposium, 1990. AP-S. Merging Technologies for the 90's. Digest.
Conference_Location :
Dallas, TX, USA
DOI :
10.1109/APS.1990.115166
