Apparatus for automatically adjusting length of antenna of radio receiver

An apparatus for automatically adjusting a length of an antenna for a radio receiver comprising:

• first means coupled to an antenna through an amplifying means and coupled to a means for outputting a signal level corresponding to a length of said antenna, said first means for generating a first signal and a third signal, said first signal being generated when said first means detects a condition where a signal outputted by said amplifying means, corresponding to an intensity of an antenna input electric field, is below said signal level corresponding to a length of said antenna, said third signal being generated when said first means detects a condition where said signal outputted by said amplifying means is above said signal level corresponding to a length of said antenna;
• second means coupled to said antenna through said amplifying means, said second means for detecting a condition that the signal outputted by said amplifying means is outside of an optimum range and, upon such detection, generating a second signal;
• third means coupled to said antenna through said amplifying means so as to receive a signal containing interference at a first terminal and receive a signal containing substantially no interference at a second terminal, said third means for detecting a condition that radio wave interference is above a predetermined level and, upon such detection, generating a fourth signal and for detecting a condition that said radio wave interference is below said predetermined level and, upon such detection, generating a fifth signal;
• fifth means having input terminals coupled to outputs of said first, second, and third means, said fifth means including means mechanically coupled to said antenna for elongating and shortening said antenna, said fifth means for elongating said antenna in response to a simultaneous generation of the first, second, and fifth signals and for shortening said antenna in response to said fourth signal or a simultaneous generation of said second signal and said third signal.