Abstract: Antenna systems for radiotelephones and other electronic devices include a first impedance matching circuit that electrically connects to a retractable antenna via a feed terminal when the retractable antenna is in an extended position and a second impedance matching circuit that electrically connects to the retractable antenna via the same feed terminal when the retractable antenna is in a retracted position. A switch opens and closes in response to detected positions of a retractable antenna to allow the first and second impedance matching circuits to electrically connect with an antenna via the same feed terminal.

Abstract: A portable radio having a transmitter power controller connected to the portable radio's receiver and transmitter for controlling the power transmission level of the portable radio, resulting in reduced power consumption by the portable radio and extended battery life. The transmitter power controller estimates the signal strength and quality of the down-link signal by determining a threshold adjustment parameter for the received signal. Thus, this invention eliminates false power adjustment caused by the interfering signals when RSSI (Received Signal Strength Level) is used as a means to estimate transmitter power level. The threshold adjustment parameter is an adjustment parameter used in adjusting the received signal to produce a degraded signal having a predetermined signal quality, and is determined by incrementally adjusting the received signal until the degraded signal is determined to have the predetermined signal quality.