| 摘要 |
<p>At the feed side (22,22') of each antenna element (15,15') comprising transmitting conductor ways formed in turnback shape in continuation and having distributed constant impedance are electrically connected variable tuning units (16,18) including an impedance adjusting element (23) and voltage variable capacitors (17,17').</p><p>Antenna feed terminals (22,22') are connected through a coaxial cable to inputterminals at a remoteset radio receiver. A tuning control signal generated within the radio receiver is fed to the voltage variable capacitors (17, 17') at the antenna circuit through the coaxial cable. The tuning control signal allows the antenna circuitto resonate ata particularfrequency within a frequency band, the frequency being variable in response to the control signal. The antenna element, having distributed constant inductance, functions to have the best antenna radiation efficiency at the resonant frequency by means of the variable tuning unit and is considerably smaller than a conventional dipole.</p><p>At the resonant frequency, the characteristic impedance at the feed terminals to the antenna circuit becomes equal to that at the receiving input terminals connected to the antenna circuit, so as to increase efficiency of transfer of the signal from the antenna to the radio receiver.</p> |
