Abstract: A method for increasing the interrogation range of an RF Tag in a radio communication system using RF Tags with multiple reflecting antenna elements. The reflecting antenna elements are predeterminately positioned, and preferably aligned, with respect to each other in the direction of expected incident RF radiation. The reflecting antenna elements are sequentially pulsed on and off such that while the first reflecting antenna element is in a signal reflecting operating state, the remaining reflecting antenna elements are in a substantially non-reflecting state, and when the second reflecting element is in a reflecting operating state, the remaining reflecting elements are in a non-reflecting state, etc. The sequential pulsing and predetermined fixed spacing between the reflector elements generates constructive interference between the reflected signals of the reflecting antenna elements which increases the power of the resulting reflected signal.

Abstract: A method (100) is provided for transmitting a traffic signal with an adaptive antenna array of a base transceiver such that a subscriber unit utilizes a non-dedicated pilot transmitted from a reference antenna element for demodulation of the traffic signal. The method (100) comprises determining a channel impulse response from a plurality of antenna elements in operative communication with the base transceiver to a receive antenna of the subscriber unit (102).

Abstract: A vehicle radio receiver has a beamsteering control system with two signal paths. One signal path generates an audio signal in response to incoming radio signals. Another signal path generates a test signal in response to the incoming radio signals. The audio signal is adjusted in response to the test signal.

Abstract: In transceiver apparatus, there is a plurality of sets (A-H) of substantially unidirectional antennae. Each set of antennae has a single radio subsystem for providing a radio output signal for transmission by one of the antennae in the set and for receiving a signal received by one of the antennae to provide an output signal from the radio subsystem. Each of the plurality of radio subsystems has a switch. The switch is operated to switch the output of the radio subsystem to a selected one of the antennae in the set for transmission of a radio signal by said selected antenna and to switch an input of the radio subsystem to a selected one of the antennae in the sets such that a signal received by said selected antenna is passed as an input to the radio subsystem.

Abstract: In a system for optimizing television reception by a television receiver receiving a diversity of input signals from a plurality of antennas, one of a plurality of combiners and television tuners selects the strongest combination of input signals for viewing and another scans the various combinations of input signals searching for a combination significantly stronger than the combination being viewed. A plurality of multiplexers selects the output signal of one combiner and transmits the selected signal to one of the tuners. A signal evaluation module evaluates the strength of the combinations of input signals and compares the strength of each combination of input signals to the strength of the viewing signal, looking for a superior signal. A control processor controls the combination of input signals selected by the combiners and the combiner output signal selected by the multiplexers.

Abstract: A radiotelephone system for motor vehicles, having a group antenna system with a plurality of antenna elements, and a mobile radiotelephone with a high-frequency input for receiving radio signals. The group antenna system contains controllable phase and/or amplitude adjusting elements, which are set so that a directed reception with a main receiving direction is available. The controllable phase and/or amplitude adjusting elements are controlled by a processor for tracking the main receiving direction azimuthally in the direction of a fixed station with the help of a tracking signal. Controllable switching-elements for reversing antenna signals for diversity reception are integrated in the signal paths of the group antenna system so that the azimuthal main direction of reception is tracked with a defined tracking by setting a combination of the switching positions of the controllable switching elements.

Abstract: A method and apparatus are provided that measures received radio communications signals to determine whether or what degree to use transmit diversity and beam forming. In one embodiment, the invention includes receiving a radio signal from a remote terminal at a plurality of antennas, comparing characteristics of the received signal as received at the plurality of antennas, determining whether reception of radio signals transmitted to the remote terminal is likely to be improved by diversity transmission based on the comparisons and transmitting radio signals to the remote terminal using diversity if the reception is likely to be improved.

Abstract: The present invention relates to a radio receiver or a diversity receiver where reception waves respectively reaching a plurality N of branches in parallel are cyclically selected at a first frequency equal to a value of the product of a symbol frequency, the plurality N being a total number of branches, and a prescribed number E equal to or greater than “2”, the instantaneous values of selected reception waves are sequentially sampled at a second frequency equal to or higher than the first frequency, and a resulting sequence of instantaneous values is cyclically split at the first frequency, whereby sequences of instantaneous values individually corresponding to the plurality N of reception waves are output. In a radio transmission system applying the above radio receiver or diversity receiver, reception waves reaching a plurality of branches are received in parallel without largely increasing hardware in scale.

Abstract: An adaptive antenna directivity control method and a system therefor is capable of reducing interference in an up-link and/or a down-link upon initiation of handoff to improve communication quality upon initiation of handoff to speed-up directivity control resulting in increasing of channel capacity. In the adaptive antenna directivity control method, a mobile station and base station to be connected with the mobile station in radio through an up-link and a down-link are governed by a supervisory station. Respective transmission signal or reception signal of a plurality of antenna elements of the base station are varied in amplitude and phase for combining in a particular orientation for establishing a directivity by a radiation pattern by combining.

Abstract: Memory (237) stores relative correction values that indicate the differences of transfer characteristics between a) a radio unit made up of transmission circuit (211) and reception circuit (212), and b) a radio unit made up of transmission circuit (221) and reception circuit (222). Correction control unit (239), by means of phase shifter (240) and amplifier (241), uses the relative correction values to correct transmission signals. In similar fashion, the adaptive array apparatus and the radio base station perform corrections in order that identical array antenna patterns are formed at times of reception and transmission.

Abstract: The invention relates to an antenna structure for a portable radio telephone comprising a helical antenna and a rod antenna. The helical antenna is inserted into the portable radio telephone, and the rod antenna is concealed when it is retracted into the telephone. The helical antenna is electrically connected to a Radio Frequency (RF) terminal in the telephone and the rod antenna is electrically connected to a ground terminal in a Printed Circuit Board (PCB) of the telephone to have a dipole structure.

Abstract: The present invention reduces the degradation in performance of one or more radio signals that are co-transmitted with a first radio signal from the same transmitting antenna in the same frequency channel and received by the same antenna due to multipath or other shared interference, where the one or more radio signals can be separated from the first radio signal.

Abstract: A multiplication circuit 152 multiplies signals, which are subjected to variable directional transmission, by weighting factors with respect to the respective antennas 101 to 103, and outputs the resultant to combining circuits 155 to 157, respectively. The signals input to the combining circuit 155 are combined and radio modulated by a radio section 104, and transmitted from the antenna 101. Whereby, in a case where variable directional transmission is performed with respect to only some terminal apparatuses, signals, which are subjected to no variable directional transmission, can be transmitted after spreading them from the respective antennas of an array antenna.

Abstract: A window glass antenna system for the reception of AM and FM radio broadcasts in an automobile includes an antenna grid applied to a window of a vehicle, that is electrically separate from a heater grid applied to the rear window. An antenna module connected to the vehicle window antenna grid is comprised of a low noise amplifier, matching, and overload protection circuits. The overload protection circuit is included between the antenna grid and the RF amplifier. When the received radio antenna signal is at the typical operating level of the amplifier, the overload protection circuit connects the output of the antenna grid to the RF amplifier. When the received signal is higher than the linear dynamic range of the amplifier the overload protection circuit provides linearity of the signal that is applied to the car radio. This process consists of two steps.

Abstract: A communications device for communicating by selecting a predetermined antenna from a plurality of antennae has a first and a second switch, each switch comprising one moving contact and two fixed contacts. The moving contact of the first switch is connected to a first antenna, the first fixed contact of the first switch is connected to a transmitter circuit, the second fixed contact of the first switch is connected to the first fixed contact of the second switch, the moving contact of the second switch is connected to a receiver circuit, and the second fixed contact of the second switch is connected to a second antenna. By switching as appropriate between antennae the attenuation of transmission and reception signals caused by the switches can be reduced.

Abstract: A satellite receiver is switchable between an operating mode wherein the receiver is capable of generating an output signal using received signals from one or a plurality of satellites, aid another operating mode wherein the receiver generates an output signal using signals received from only one satellite. The former operating mode is useful when the receiver is operating in a mobile environment. The latter operating mode is useful when the receiver is operating in a fixed environment. The receiver is configured to detect the mode in which it is operating. The receiver comprises at least two recevier arms for processing a broadcast signal from a selected one of two satellites. The receiver disables one of the arms when the receiver is stationary.

Abstract: A scalable switch matrix and demodulator bank architecture for a satellite payload processor wherein the demodulators are connected to the output ports of the switches as the data load on the uplink beams varies. The switch matrix includes a first switch layer for receiving the uplink transmission beams and a plurality of demodulators connected to the output parts of the first switch layer. The number of demodulators is limited by the number of active uplink sub-bands which is generally less than the number of sub-bands per beam times the number of transmission beams. Thus, only a relatively few number of demodulators are distributed among the uplink transmission beams as required. This results in a readily scalable architecture having higher demodulation utilization rates than dedicated demodulation architectures.

Abstract: The present invention is a system for increasing Signal-to-Noise Ratio (SNR) in a wireless communication system comprising a plurality of antennas each antenna providing a signal, a device for selecting a subset of signals provided by the plurality of antennas, a maximum ratio combiner for summing the selected subset of signals provided by the plurality of antennas, and a decision device for measuring the selected subset of signals against a predefined threshold. The device for selecting the subset of signals is coupled to the plurality of antennas. The maximum ratio combiner is coupled to the selected subset of signals and the decision device for measuring the selected subset of signals against a predefined threshold. The decision device is coupled to the selecting device such that one selected signal of the selected subset of signals is replaced by an unused signal provided by the plurality of antennas.

Abstract: A method of selecting between first and second antennas in a quadrature amplitude modulation receiver having in-phase (I) and quadrature (Q) signal channels for demodulating signals received by the antennas, comprising the steps of imultaneously connecting the first antenna to the I channel to obtain a first output signal having a first amplitude, and the second antenna to the Q channel to obtain a second output signal having a second amplitude; measuring the first and second amplitude to obtain a greater amplitude for one on the antennas; and switching to said of the antennas having the greater amplitude for demodulating the received signals.

Abstract: In this invention, a diversity antenna and dual-band antenna are attached to the display portion of the portable information device. The dual-band antenna is connected to a Bluetooth circuit and wireless LAN 802.11a reception circuit. The diversity antenna is connected to a wireless LAN 802.11a transmission circuit. The Bluetooth circuit is not influenced by the wireless LAN 802.11a transmission system circuit. This invention can provide a compact portable information device.

Abstract: A remote convenience system (10) and an associated method provide for remote control a convenience function. A portable transmitter unit (12) is operable for remote function requests. The transmitter unit (12) includes circuitry (32) for transmitting a signal (18) that conveys a remote function request. A receiver/controller unit (14) receives the transmitted signal (18) and causes performance of the remotely requested function. The receiver/controller unit (14) includes a plurality of antennae (52), each for picking-up the transmitted signal (18) and outputting an electrical signal that conveys the remote function request. Each of the antennae (52) is configured to have an ability to pick-up the transmitted signal (18) that is dependent upon direction from the receiver/controller unit (14) to the transmitter unit (12). The ability of each of the antennae (52) is different from the ability of the other antennae.

Abstract: A radio-frequency (RF) repeater, including a first repeating section which is adapted to receive and amplify forward-signals from a first transceiver so as to generate amplified-forward-signals and to radiate the amplified-forward-signals to a second transceiver. The first section also receives and amplifies reverse-main-signals from the second transceiver so as to generate amplified-reverse-main-signals and transmits the amplified-reverse-main-signals to the first transceiver. The repeater includes a second repeating section which is adapted to receive and amplify reverse-diversity-signals from the second transceiver so as to generate amplified-reverse-diversity-signals and transmits the amplified-reverse-diversity-signals to the first transceiver.

Abstract: A cradle for a wireless device such as a cellular telephone. The cradle provides a second antenna for antenna diversity operation of the wireless device. Optionally, the cradle contains any of hardware circuitry, processing, and software to provide antenna diversity operation in conjunction with the wireless device.

Abstract: A high density electronic switching matrix (ESM) includes several splitting modules (200) arranged along a first axis, each including a signal input (202) and several splitter outputs (204). The ESM (500, 600) further includes several switching modules (400) arranged along a second axis perpendicular to the first axis. Each switching module (400) includes switching inputs (402) coupled individually to an output of each of the splitting modules (200). The ESM (500, 600) is further characterized by couplings between the splitter modules and the switching modules. The couplings are formed by mating male and female connectors (300) integrated into the splitting modules and the switching modules. The couplings support extremely high frequency operation. The splitting modules (200) and the switching modules (400) may thus be coupled closely together to form a dense, high frequency, switching matrix, and may be stacked upon one another.

Abstract: A method of effectuating frequency switching by using two self-oscillating frequency reducers having a common input includes the use of a three-way coupler to connect two field effect transistors (or two bipolar junction field effect transistors) and two dielectric resonator oscillators between a low-noise amplifier and an intermediate frequency (IF) amplifier, so as to effectuate switching between different frequency ranges. Thus, a simplified switch circuit for switching frequencies is possible to enable reduced manufacturing cost and reduced volume of device.

Abstract: An alternative frequency of e. g. a digital shortwave signal like a DRM signal can easily and satisfactorily be checked whether or not the same service is transmitted before a fast seamless switching to this alternative frequency can be performed. The inventive method to perform such a checking is characterized by a respective correlation of at least two sets of samples taken from the signal transmitted on the alternative frequency having a predetermined time relationship (&Dgr;tcorr) and a comparison of said respective correlation results, i.e. comparison of the time (t1) of occurance of a correlation peak included in a first correlation result with the time (t2) of occurance of a correlation peak included in a respective further correlation result, to verify that both services are the same when the time relationship (|t2 l -t1|) between said correlation peaks is the same as said predetermined time relationship (&Dgr;tcorr) of the at least two sets of samples.

Abstract: A diversity combiner and associated methods are introduced. According to one example implementation, an apparatus comprising a multi-antenna combiner and a combiner controller is presented, wherein the multi-antenna combiner selectively modifies each of two or more received wireless communication signals to generate a composite signal from at least a subset of the modified received signals. The combiner controller, coupled to the multi-antenna combiner, dynamically generates control parameters associated with each of the received signals to control combiner modification of the signals in generating the composite signal based, at least in part, on one or more quality values generated during baseband processing of previous composite signal(s).

Abstract: The invention concerns a method and a device for receiving a signal transmitted by a source by means of a plurality of antennas, in which a plurality of beam signals are obtained by weighting the signals received by the different antennas. The beam signals are correlated with the replica of a reference signal transmitted by the said source and then combined by means of coefficients obtained from correlation results.

Abstract: An electronic device comprises first and second antennas for a first radio communication scheme that uses a diversity scheme, and a third antenna for a second radio communication scheme arranged between the first and second antennas.

Abstract: A satellite digital audio radio receiver system and method. The inventive receiver includes a circuit for down-converting a first ensemble in a received combined signal in a first mode of operation and for down-converting a second ensemble from the received combined signal in a second mode of operation. The first ensemble includes a first signal received from a first transmitter, a second signal received from a second transmitter, and a third signal received from a third transmitter. The second ensemble includes a second signal from the first transmitter, a second signal from the second transmitter, and a second signal from the third transmitter. A controller is included to selectively switch the circuit from the first mode to the second mode. The first ensemble comprises first, second and third frequency slots and the second ensemble comprises fourth, fifth, and sixth frequency slots.

Abstract: The invention relates to a diversity reception system for motor vehicles for digitally modulated terrestrial and/or satellite radio signals in a frequency range above 1 GHz. The system includes an antenna arrangement which supplies the reception signal to a radio receiver. The antenna arrangement is an antenna system having several individual antennas and several antenna components, and contains a controllable logic switching device. The individual antennas and the several antenna components are positioned on the vehicle so that different reception signals are available at the antenna connection point via discrete switching positions of a controllable logic switch. A reception level testing device comparatively determines the reception level contained in the data flow in the HF-channel with an HF channel bandwidth B.

Abstract: A diversity antenna apparatus and method adaptable for use with communication equipment is provided which can assure an acceptable transmission and/or reception condition in three principal dimensional (X,Y,Z) directions. The diversity antenna apparatus may comprise a plurality of antennae for transmitting and/or receiving a circularly polarized wave and an antenna selection circuit which selects one of the antennae for transmission and/or reception based on information representative of reception levels of the antennae. A first group of the antennae may provide a first substantially semispherical radiation pattern and a second group of the antennae may provide a second substantially semispherical radiation pattern such that the first and second groups of antennae as a whole provide a substantially spherical radiation pattern.

Abstract: A radio reception apparatus receives signals from all directions through a plurality of directivities, and generates a delay profile to each directivity. The apparatus selects a path having the largest received signal among a plurality of delay profiles generated by suppressing interference signals after thus narrowing down directions.

Abstract: A synchronization system within a dual antenna receiver employs two timing recovery loops each coupled to a different antenna input. Segment sync lock (detection of a segment sync in the data stream) by one timing recovery loop prompts selection of the timing error from the corresponding timing recovery loop for timing recovery within both loops. Both timing recovery loops are then synchronized utilizing the selected timing error. If sync lock for the selected loop is lost, the other loop is selected to provide timing error to both loops.

Abstract: An apparatus and method are provided for transmitting audio signals from an auxiliary source such as a satellite broadcast receiver or a CD or cassette player to a radio receiver located, for example, in a vehicle, using a wireless link. The apparatus comprises a scanning device for locating open radio frequencies in the RF spectrum of the radio receiver. The apparatus displays plural RF channel options on a display device and provides a selection device with which a user selects an RF channel. The apparatus modulates the audio signals using the selected radio frequency, and the user tunes the vehicle radio receiver to the selected RF channel. The scanning device continuously scans for open RF channels and monitors the quality of the RF channel already selected for use as the wireless link. The apparatus provides the user with an indication to select another open channel when the RF channel in use degrades.

Abstract: A wireless call system enables even a bedridden person to easily answer a visitor. The wireless call system has an outdoor unit (3) installed on the outside of an entrance of a structure having a door (13) lockable with an electronic lock (15), for calling a resident in the structure, and an indoor unit (9) connected to the outdoor unit (3) by radio, for informing the resident of the presence of a visitor upon receiving a signal from the outdoor unit (3) and allowing the resident to answer the visitor through the outdoor unit (3). The outdoor unit (3) has an image pickup unit (23) for picking up an image of the visitor making a call with the outdoor unit (3). The indoor unit (9) is portable and has a display (53) for displaying the visitor's image picked up by the image pickup unit (23) and control buttons (55) for unlocking the electronic lock (15) if necessary.

Abstract: The invention relates to a method and an arrangement for establishing a connection between two fixed nodes in a mobile radio system. Adaptive antennas are utilized to achieve narrow beams. The connection is established via a reflecting body.

Abstract: A universal remote control radio frequency transmitter for use with garage door operators, gate operators and other barrier movement operators is programmable through the use of external switches. The same switches are used after programming for causing the transmitter to transmit an RF signal at about the selected frequency and with a code corresponding to the programmed code. A plurality of RF frequencies are generated by a single RF circuit and a single loop antenna. The selected frequency is determined by digital controller logic and PIN diode shorting in and out selected reactive elements in the RF circuit.

Abstract: The present invention provides an improved receiver capable of receiving either a satellite broadcast signal or a cable TV signal associated with a TV. The inventive receiver comprises a first BPF for filtering received broadcast signals, a first local oscillator for generating a first oscillation signal, a first mixer for generating a first IF signal, a SAW filter producing a waveformed band signal, a second local oscillator, for generating a second and a third oscillation signal, a second mixer for generating a second and a third IF signal, a switching block for switching the second and the third IF signal, a second BPF for producing a baseband channel signal selected from the cable TV signal, a first LPF for producing a baseband I signal of satellite broadcast channel, a shifter for shifting a phase of the third IF signal, a third mixer for generating a phase-shifted third oscillation signal, and a second LPF for producing a baseband Q signal of satellite broadcast channel.

Abstract: Noise and multipath distortions in a broadcast receiver are reduced by an optimal antenna/frequency diversity concept in which the distortions in the audio signal are evaluated to choose a different antenna and/or a different frequency for at least signal parts.

Abstract: A probing scheme for diversity antenna branch selection makes use of a physical waveform frame structure that includes a diversity selection portion. The diversity selection portion may be located anywhere in the physical waveform frame structure and includes one or more antenna branch probing portions. Several antenna branch switching time intervals are interleaved with the antenna branch probing portions. Several repeated Orthogonal Frequency-Division Multiplexing (OFDM) symbols are used to form the antenna branch probing portions and the switching time intervals. Diversity reception in radio frequency (RF) communications is performed by receiving a frame having the diversity selection portion with a system having L antenna branches and n RF receivers, and then taking measurements from n of the L antenna branches during one of the antenna branch probing portions.

Abstract: A synchronization system within a dual antenna receiver employs two timing recovery loops each coupled to a different antenna input. The timing error computed within each timing recovery loop is differentiated by a high pass filter and compared to a predefined threshold indicating convergence. Both sampling rates are then synchronized utilizing the timing error from whichever loop converges first. If synchronization lock for the selected loop is lost, the other loop is selected to provide timing error to both loops.

Abstract: An antenna switch diversity algorithm, and systems and methods to provide antenna diversity by implementing the algorithm in, for example, an IEEE 802.11a compliant environment, are presented. In accordance with the algorithm, one antenna of at least two antennas is designated as a default antenna at a communications device that sends and receives transmit and receive packets. The default antenna designation is changed depending on long-term and short-term learning processes implemented in, for example, software and hardware. The long-term and short-term learning processes analyze packet transmission and reception results of the antennas. The antenna switch diversity algorithm is applicable to multiple antennas.

Abstract: Antenna received signals 101-1 to 101-n are input to weighting coefficient calculation section 103. Weighting coefficient calculation section 103 determines weighting coefficients so as to eliminate interference using antenna received signals 101-1 to 101-n and known signal and combines them into weighted/combined signal 107. Envelope variation detection section 116 detects variations in the envelope of the weighted/combined signal. Interference mixing time detection section 108 detects the interference mixing time from the output of envelope variation detection section 116. Envelope variation detection sections 117 to 119 detect envelope variations of the received signals. Combination system control section 113 switches switch section 114 so that the received signal with the least envelope variation may be output at the interference mixing time.

Abstract: A reception diversity control method for receiving and demodulating receive signal by multiple receiver circuits, selecting demodulated data received by a receiver circuit in the best reception state from digital demodulated data obtained, the method having the steps of: taking out voice existence information included in the demodulated data selected; and turning on the power sources of all the multiple receiver circuits when the voice existence information indicates that voice information exists, or turning off the power sources of the multiple receiver circuits except a predetermined receiver circuit of the multiple receiver circuits when the voice existence information indicates that no voice information exists.

Abstract: An antenna circuit is described which makes it possible to suppress intermodulation products. This antenna circuit includes an antenna connection device to which at least one first antenna can be connected, and the antenna connection device can be connected to an output of the antenna circuit over at least two signal paths. An antenna signal can be transmitted over each signal path. Transmission of a second antenna signal over a second signal path is attenuated by a predetermined attenuation value in comparison with a transmission of a first antenna signal over a first signal path. An analyzer unit is provided to determine the level of a weighting signal which is derived from an antenna signal transmitted to the output of the antenna circuit. An operating device is provided to connect only the first signal path to the output of the antenna circuit when the detected level is below a first predetermined level.

Abstract: The invention relates to a diversity reception system for motor vehicles for digitally modulated terrestrial and/or satellite radio signals in the frequency range above 1 GHz. The system includes an antenna arrangement of which the reception signal is supplied to a radio receiver. The antenna arrangement is designed as an antenna system having several individual antennas and several antenna components, and contains a controllable logic switching device. The individual antennas and the several antenna components are positioned on the vehicle so that for discrete switching positions of the controllable logic switch, reception signals that are different in terms of diversity are available at the antenna connection point. A reception level testing device is provided for the comparative determination of the reception level contained in the data flow in the HF-channel with an HF channel bandwidth B.

Abstract: To provide an interference-signal removing apparatus for improving the quality of interference-removed input signals by removing only interference signals having a comparatively high level from input signals including wide-band signals and narrow-band interference signals. For example, input-signal control means 1 and 2 restrict effective word lengths of digital values of input signals, interference-signal estimation means 3 estimates interference signals included in input signals in accordance with effective-word-length-restricted input signals, interference-signal extraction means 4 extracts interference signals included input signals in accordance with an estimation result of the interference-signal estimation means, and interference-signal removal means 5 removes extracted interference signals from input signals.

Abstract: A method of controlling an antenna signal combiner in a vehicle having a navigational system, a broadcast receiver, and multiple antenna elements. The method comprises the steps of the broadcast receiver receiving broadcast signals from a broadcast tower. Then, determine first position coordinates of the vehicle using the navigation system. Next, determine second position coordinates of the broadcast tower and then combining signals from the multiple antennas to steer an antenna beam from the first position coordinates towards the second position coordinates. This method allows for accurate and timely tracking of a broadcast signal.

Abstract: A radio transceiver circuit which includes an antenna, a transmitter, a receiver, an antenna switching circuit for selectively connecting the transmitter and the receiver to the antenna, and a power source for driving the transmitter and the receiver. The antenna switching circuit includes two semiconductor elements. The current (|BRX, |BTX) provided by the power source to the receiver and to the transmitter is directed through the respective semiconductor elements which are each set to its conductive electrical state by the respective current (|BRX, |BTX) and thereby selectively coupling the radio signal between the receiver and the transmitter to the antenna.