Abstract: A communication device (400) with a polarization diversity antenna configuration, having a first antenna (410) with a first plane of polarization and a second antenna (412) with a second plane of polarization. Signal strength of a demodulated signal when the antenna switch (420) is coupled to one of the antennas (410, 412) is measured by a signal strength measuring circuit (440) to generate a short-term average signal power (SA) representing signal strength over a first predetermined number of symbol periods, a medium-term average signal power (MA) representing signal strength over a second predetermined number of symbol periods, and a long-term average signal power (LA) representing signal strength over a third predetermined number of symbol periods, greater than the second predetermined number of symbol periods and first predetermined number of symbol periods. Switching between antennas (410, 412) is made in response to differences between SA, MA and LA.

Abstract: An omnidirectional antenna (100) includes a resonator (102) and a ground plane (104).

Abstract: An antenna (105) for receiving radio frequency (RF) signals includes a conductive element (300) having a first electrical length and a first operating impedance and a transmission line (315) having a second electrical length and a second operating impedance for resonating the conductive element (300) at a predetermined operating frequency. A coaxial element (305) having a third electrical length is coupled to the conductive element (300) and the transmission line element (315) for converting the first operating impedance to the second operating impedance. When the conductive element (300) is resonated, the first, second, and third electrical lengths are substantially equal to a quarter wavelength or an odd multiple thereof at the predetermined operating frequency.

Abstract: A satellite receiver system provides acquisition and frequency tracking of a Doppler-shifted radio signal received from an orbiting satellite. The satellite receiver system includes a Costas phase-lock loop that receives the radio signal and provides an error signal at an error signal output for controlling a conversion frequency generated by a voltage controlled oscillator. The voltage controlled oscillator is coupled to the Costas phase-lock loop and generates the conversion frequency for down-converting the radio signal in the Costas phase-lock loop. The satellite receiver system further includes a Doppler frequency acquisition and tracking element coupled to the voltage controlled oscillator. The Doppler frequency acquisition and tracking element adjusts the conversion frequency to compensate for a Doppler frequency shift occurring in the radio signal due to orbital motion of the orbiting satellite.

Abstract: An antenna system for a communication receiver comprising a first circuit portion located on a first circuit substrate, and a second circuit portion located on a second circuit substrate comprises an antenna which is located on the first circuit substrate and at least one circuit element of the second circuit portion being positioned in proximity to the antenna to effect interaction with the antenna. A loss cancellation element comprises a conductive sheet metal element and an insulating material enclosing the conductive sheet metal element. The loss cancellation element is affixed with an adhesive to the second circuit substrate and interposed between the antenna and the interacting circuit element to reduce the interaction between the antenna and the circuit element.

Abstract: A loop antenna includes a circuit board having a ground plane layer. A formed loop is located on one side of the circuit board and a transmission line is located on the opposite side of the circuit board. Capacitors interconnect the ends of the formed loop and the transmission line. The transmission line is a microstrip formed by the ground plane layer in a microstrip portion.The circuit board includes RF circuitry that is located on the side of the circuit board opposite to the transmission line so that the ground plane shields the circuitry from the transmission line.

Abstract: A receiver (200) includes an automatic frequency controller that determines the frequency of a receiver signal, and a calculates a frequency error from the received signal. The frequency error is used to calculate a correction factor (316) that is used to adjust the frequency of an oscillator (308) in response to the determined error.

Abstract: An integral portable receiver/antenna system is provided which includes an isolation coupler element exhibiting a geometry which is substantially closed upon itself and which is situated between the receiver antenna and the input of the receiver. A portion of the antenna element is distributively coupled to a portion of the coupler element. The receiver/antenna system further includes a ground plane which is sufficiently close to a portion of the coupler element such that the ground plane is distributively coupled to the coupler element. The coupler element prevents the formation of undesired signal loss paths between the antenna and the receiver and provides for impedance matching the input of the receiver to the antenna. The coupler element also couples signals to the receiver input which would otherwise be lost to the ground plane.

Abstract: A small closed loop antenna is formed by a flat metal member formed into a U-shape which also serves as the front, back and top surfaces, or parts thereof, of the housing for a portable communications receiver. Connected to the open (bottom) end of the arms is an isolation network providing an optimum antenna ground and a reactance network which applies a capacitive reactance across the antenna and isolation network so that the conductive member forms an antenna that detects the H-field of the electromagnetic wave to be received. The reactance network is tunable to adjust the antenna for reception at particular frequencies.