Abstract: A circuit for matching an amplifier to a radio-frequency line is described. In order to minimize the number of components required for matching the amplifier to different frequency bands, the circuit has a first capacitance for outputting the negative half-cycle of the transmission signal, which is rectified by a diode and is stored in a second capacitance. The stored negative voltage is, if required, fed back via two resistors and an inductance to a further diode.

Abstract: The invention relates to an arrangement for matching transmitting antennas in mobile stations, especially in mobile stations applying new transmission technologies, as well as to an arrangement for protecting a power amplifier feeding an antenna. In order to match an antenna (260), the strength of the field (re) reflected from the antenna is continually measured. The measurement data is used in controlling an antenna matching circuit (250) so that the strength of the reflected field is minimized. The measurement is carried out using a circulator (220) which also provides isolation, i.e. prevents the field reflected from the antenna from propagating back to the power amplifier (PA). In a multi-band apparatus, the band in use is also taken into account in the matching. The structure according to the invention saves space, as the number of relatively large components becomes smaller.

Abstract: The present invention concerns an antenna arrangement (29) including: an antenna (A) able to transmit data in the form of a radiofrequency signal; a transmitter (32) including a preamplifier (33) and a first transistor (36) connected in cascade, this transmitter being able to provide a radiofrequency signal containing the data to be transmitted to the antenna; and coupling means (30) connected between the antenna and the transmitter, and including a phase lag circuit (42) able to achieve the coupling of the antenna and the transmitter. The coupling means further include switching means (43) connected between the system's earth and the source terminal of the first transistor of the transmitter, so as to be able to switch the latter to an ON state, respectively to an OFF state, when said antenna is, respectively is not, in transmission phase.

Abstract: A peak limiter is intended to limit the peak of a signal that has a given frequency, in an assembly comprising other signals of lower amplitude and different frequencies. The peak limiter includes a circulator inserted into a line transporting all the signals. A first branch of the circulator is connected to a line on its upstream side. Its second branch is connected to a line on its downstream side. It's third branch is connected to a reference terminal via the combination of a band-pass filter centered on the given frequency, a threshold element, and an adapted load connected in series.

Abstract: An RF filter for a cellular radio receiver whose architecture includes a combination of signal circulators and bandpass filters which operate to selectively notch out sub-bands of the two cellular bands of the cellular radio transmission spectrum so that the sub-bands of both cellular bands can be separately directed to a radio capable of receiving either or both the A or B-band signals. In its preferred form, the architecture of the filter includes two circulators, three bandpass filters having mutually different bandpass characteristics, covering selected portions of the A and B band and a diplexor.

Abstract: The present invention is directed to providing a full duplex communication system capable of providing actual wireless transmission rates on the order of 125 Mb/s, or higher, with relatively high transmission power on the order of 0.5 to 2 watts (W) or higher, with a high signal-to-noise(S/N) ratio, a bit error rate on the order of 10−12 or lower, 99.99% availability, and with relatively simple circuit designs. Exemplary embodiments can provide these features using a single compact and efficient, low distortion transceiver design based on high power (e.g., 0.5 W) monolithic millimeter wave integrated circuits (MMICs), having a compression point which accommodates high speed modems such as OC-3 and 100 Mb/s Fast Ethernet modems used in broadband networking technologies like SONET/SDH (e.g., SONET ring architectures having self-healing ring capability). By applying high power MMIC technology of conventional radar systems to wireless duplex communications, significant advantages can be realized.

Abstract: The course of an oscillating signal is controlled in mutually alternative first active component (31) and second active component (32), both of which can be set into active state by a certain first value of a control signal brought to the component and which are in inactive state with a certain second value of the control signal. The signal is directed to pass through the first active component (31) by setting it into active state by a control signal (33) brought to it. At the same time, the second active component (32) is prevented from affecting the course of the signal by setting a control signal brought to it to a second value (107, 111).

Abstract: A portable radio terminal comprises a housing, a radio circuit included in the housing, a matching circuit mounted on the top of the housing at a position which is offset from the longitudinal center line of the housing, a load connected to the tip of the matching circuit, and a linear antenna connected to the load. This portable radio terminal further comprises load changing means for changing the value of the load. The matching circuit may comprise a meander matching element, a zigzag-shaped matching element, a helical matching element, a conical matching element, a rectangular helical matching element or a pyramid helical matching element which are formed so as to a predetermined shape, such as a meander shape, a zigzag shape, a helical shape, a conical shape, a rectangular helical shape or pyramid helical shape.

Abstract: A monolithic active frequency selection circuit includes an input presenting a frequency-dependent impedance and a first gain block configured to provide less than unity voltage gain, a high input impedance and a low output impedance. An output of the first amplifier is coupled to the frequency selection circuit input. The frequency selection circuit includes a first phase shifter that, in one aspect, is formed by a first capacitor coupled between the first port and a reference voltage. The frequency selection circuit also includes a second amplifier configured to provide greater than unity voltage gain. The second amplifier has an input coupled to the output of the first amplifier and an output coupled to the input of the first amplifier. The frequency selection circuit further includes a second phase shifter, which may be formed from a capacitor coupled between the output of the second amplifier and a reference voltage.

Abstract: The invention relates to a receiver system for the reception of a series of ultrashort, pulsed electromagnetic signals. Signals of this type usually require an extremely fast-acting receiver, necessarily situated in close proximity to the antenna. According to the invention, the presence of several passive components near the antenna will suffice.

Abstract: A time division duplex switching circuit provides for selectively coupling signals between an antenna and a front stage transceiver circuit. The switching circuit is operative in a transmit mode and in a receive mode, and includes: a transmitter amplifier having an input and an output; a receiver amplifier having an input and an output; a first circulator including a first port coupled for communication with the front stage transceiver, a second port selectively coupled with the output of the receiver amplifier via a first switching, and a third port selectively coupled with the input of the transmitter amplifier via a second switching; and a second circulator including a first port coupled for communication via the antenna, a second port coupled with the input of the receiver amplifier, and a third port coupled with the output of the transmitter amplifier.

Abstract: A mobile radio telephone includes a transmitter output stage and an antenna. An impedance matching network is inserted between the transmitter output stage and the antenna. The matching network has a transformation factor (T) for adjusting the transmitter load impedance (ZPA) to match with the antenna input impedance (ZAAnt). The impedance matching network includes at least two impedance transformers that form at least two transformation factors by alternatively connecting in parallel the two impedance transformers.

Abstract: The present invention is a method and apparatus for isolating high frequency signals in a printed circuit board. A barrier strip (36) of staggered elongated grounding slots is positioned on the circuit board to prevent stray signals from leaking from one portion of the board to another. To further improve signal isolation, additional grounding holes (80) are placed around those areas where a trace on a circuit board makes the transition from one layer to another layer in a multilayer circuit board. In addition, microstrip filters (56, 58) are attached to the power or control traces of circuitry on the board at positions where the traces cross from one section of the board to another in order to filter out any stray rf signals that may be induced by the transmitter onto the power and control traces.

Abstract: A power amplifier circuit for a radio transceiver has a linear mode amplifier and a saturated (nonlinear) mode amplifier, a diplex matching circuit coupled to the linear mode amplifier for impedance matching and for separating transmitted signals in a plurality of frequency bands, a low pass matching circuit coupled to the output of the saturated mode amplifier and means for selectably placing the power amplifier circuit in a linear mode for or a saturated mode, corresponding to digital and analog modes of operation of the cellular telephone, respectively. In linear or digital mode, the linear amplifier is biased in the on state and the saturated mode amplifier may be biased in the off state. Similarly, in the saturated or analog mode of operation, the saturated mode amplifier is biased in the on state and the linear amplifier may be biased in the off state.

Abstract: A harmonic filter is added to a radio frequency filter comprising at least one transmission line resonator (R1; R2; R3) to filter harmonic multiples of the filter's operating frequency. Coupling to the harmonic filter occurs through matching couplings and transmission lines (7; L1 to L9; L20; L28) in the filter or via the electromagnetic field of said transmission line resonator (R1; R2; R3). The harmonic filter advantageously comprises striplines (L13 to L19; L21 to L27; L29 to L49) manufactured in conjunction with the other stripline structures in the filter.

Abstract: In a transceiver switchover arrangement for alternating connection of a first and a second receiver apparatus, and a first and a second transmitter apparatus, with a single antenna, the first receiver apparatus and the first transmitter apparatus are designed for a first frequency band f1, and the second receiver apparatus and the second transmitter apparatus are designed for a second frequency band f2. By means of on-off switches, in connection with two line sections, of which each represents a quarter-wave line for f2, and which serially represent a quarter-wave line for f1, one of the apparatuses is coupled to the antenna according to the mode of operation.

Abstract: It is an object of the present invention to provide a portable terminal which reduces an antenna standing-wave ratio and absorbs reflected waves without inserting an isolator so that a stable operation can be obtained efficiently with a compact, low-price body.

Abstract: An integrated circuit includes a single pole double throw switch including a transmitting and receiving port, a transmitting port, and a receiving port. A transmission switch is coupled between the transmitting port and the transmitting and receiving port. A reception switch is coupled between the receiving port and the transmitting and receiving port. The reception switch includes a field effect transistor having a gate, a drain and a source. A voltage generating circuit receives first and second power supply voltages. The first power supply voltage is greater than the second power supply voltage. The voltage generating circuit generates a third voltage lower than the second power supply voltage and applies the third voltage to the gate of the field effect transistor of the reception switch during transmission.

Abstract: The switch attenuator of the invention includes: a first terminal connected to an antenna; a second terminal connected to a transmitter; and a third terminal connected to a receiver, thereby switching a first state and a second state.

Abstract: In a mobile communication device, a power amplifier amplifies the power of a signal to be transmitted. A transmitter filter limits the frequency band of the amplified signal to a predetermined frequency band for transmission. The signal limited in frequency band is transmitted via an antenna. Output power control circuitry controls the output power of the signal to be transmitted and has an output power sensor and an automatic power control circuit. The output power sensor succeeds the transmitter filter in the direction of flow of the signal to be transmitted, and senses the output power of the signal. The automatic power control circuit controls the gain of the power amplifier such that the output power sensed by the output power sensor coincides with a preselected reference value.

Abstract: A radio transceiver is provided for wireless communications, having an interface connection that is selectable between either an antenna or a cable interface. The radio transceiver is engaged to the antenna through an impedance matching network which translates the antenna impedance to match that of the radio transceiver. The radio transceiver can, alternately, be connected to external test equipment or performance enhancement equipment through the cable interface. Since the radio transceiver has the same impedance as most external test equipment, the antenna matching network is not required or used when test equipment is connected to the cable interface. In the present invention the cable interface at least partially disconnects the matching network whenever the cable interface is in use. Once the antenna has been disconnected, the impedance of the cable interface matches that of the radio transceiver.

Abstract: A transmit/receive radio set having a transmitter output stage, a receiver input stage, and an antenna switching device for change-over between transmission and reception by a single antenna. Two impedance transformers are provided at the output of the transmitter output stage. A switching circuit effects a change-over of the output impedance of the transmitter output stage during transmission and reception by controlling the impedance of at least one of the impedance transformers.

Abstract: An adaptive multi-receiver shared antenna matching system and corresponding method includes an antenna (101). A plurality receiver devices (103) are operably coupled to the antenna (101). Degree of coupling between each of the receiver devices (103) and the antenna (101) is dynamically alterable dependent on a degree of coupling model (200) and different signals received by the antenna (101).

Abstract: An FM radar system of more simple construction, smaller size, lower cost and improved performance is provided in which circulators of any type in the prior art are eliminated by constructing a transceiver comprised of a transmitting part and a receiving part, each formed on a common dielectric plate and having a dedicated transmitting antenna and a dedicated receiving antenna respectively. The antennas comprise planar array antennas, in contrast to the solid antennas used in prior art systems. The planar array antennas are also formed on the single dielectric plate. The transmitting part comprises a plurality of transmission antennas and a plurality of frequency multipliers coupled to said transmission antennas. The receiving part comprises a plurality of receiving antennas which are coupled to a plurality of switches through a plurality of mixers, frequency multipliers, and low noise amplifiers.

Abstract: The present invention relates to an arrangement for separating transmission and reception accomplished through one and same antenna (A) in a transceiver, said arrangement comprising a filter and a switching element (K) and being provided with a common port to be coupled to the antenna (A), a transmitter branch (TX) port (T) to be coupled to the transmitter of the transceiver and a receiver branch port (RX) port (R) to be coupled to the receiver of the transceiver, and in which, as a response to a control signal, the switching element couples operationally to the common port alternatively the transmitter branch port (T) and the receiver branch port (R). The arrangement comprises a filter (S.sub.T,S.sub.F,S.sub.1,S.sub.2) including transmission line resonators, said filter being provided with adaptation couplings to be coupled to the transmission line resonators and for accomplishing couplings between the transmission line resonators.

Abstract: An antenna suitable for a radio telephone which is primarily comprised of a duplexer, a transmitter, and a receiver. The antenna is fabricated as a cover for sealing a box-like duplexer. At the same time, the cover is set up by a microstrip antenna which is comprised of a dielectric substrate and conductive pattern layers formed on the top and bottom surfaces of the dielectric substrate.

Abstract: A radio transceiver having improved impedance matching characteristics between a rod-like antenna and transmitting and receiving portions. An impedance matching circuit is provided between the antenna and a duplexer to impedance-match therebetween at a frequency within a desired signal frequency band. A transmitting signal and a receiving signal may have substantially different frequencies in which case the impedance matching circuit operates advantageously in a range between these signals, respectively. The impedance matching circuit includes a first inductor inserted between the antenna and the duplexer, a first capacitor inserted between the antenna and ground potential, and a parallel resonance circuit composed of a parallel circuit of a second capacitor and a second inductor inserted between the duplexer and ground potential.

Abstract: A bidirectional amplifier apparatus comprising a plurality of diodes located in a ring structure around an amplifier device to be switched. Each pair of diodes are spaced approximately one quarter wavelength, at the frequency to be passed, in order to maximize isolation across the "off" diode pairs. Use of transmission line devices of approximately one quarter wavelength, at a desired frequency, provide a high impedance at the desired frequency while attenuating higher frequencies where the transmission line devices length approach one half wavelength. The use of the transmission line devices also provide a ground bias for the paired diodes.

Abstract: A radio frequency switching device package having improved isolation is described. The present invention allows for a radio frequency device packages such as PIN diodes to improve their isolation characteristics by adding an extra wire bond between the anode of the PIN diode and an extra leadframe that is added to the device package.

Abstract: A single-block ceramic filter (102) is coupled to two antennas (142 and 144) for providing both antenna duplexing and antenna-switched diversity in a duplex radio transceiver (100). One antenna (142) is coupled by the filter (102) to a transmitter (132), and both antennas (142 and 144) are switchably coupled by the filter (102) to a receiver (130) by diversity control circuitry (101) in response to a diversity control signal (137). A microcomputer (134) in the transceiver (100) is coupled to the receiver (130) for monitoring the received signal strength (135). When the received signal strength (135) drops in level indicating that the signal being received on one of the antennas (142 or 144) has become degraded due to fading or other interference, the microcomputer (134) changes the binary state of the diversity control signal (137) for switching the receiver (130) to the other one of the antennas (142 or 144 ).

Abstract: Transmission-Reception Separating Filter with a PIN diode. A PIN diode is arranged in the transmission channel of the transmission-reception separating filter that has the transmission channel for forwarding a high-frequency current from a transmitter to an antenna. A rectifier is provided that generates a control current for the PIN diode from the high-frequency current flowing in the transmission channel. As a result, a separate power supply is not required for controlling the PIN diode in the transmission channel.

Abstract: A directional coupler (103) for radio equipment couples a radio frequency signal from an input of a microstrip transmission line (309) to an output and provides a directionally coupled output via a stripline microstrip (311). Open circuit microstrip transmission line stubs (313 and 315) are tuned to a quarter wavelength of the third harmonic of the radio frequency to provide third harmonic rejection within the directional coupler.

Abstract: A signal switching apparatus for switching between a 1/4 wavelength transmission line, which transmits a transmission signal, and a 1/4 wavelength reception line, which receives a reception signal, which share a common antenna. The apparatus sets the characteristic impedance of one of the 1/4 wavelength lines to be zero while the other 1/4 wavelength lines is set to infinity so that the switching operation can be effected without passing the transmission and reception signals through semiconductor switches.

Abstract: A combined switch and filter comprising coupled first and second quarter-wave transmission line sections and switching elements for providing selective coupling and filtering between ports of the switch coupled to the ends of the quarter-wave sections.

Abstract: A microphone circuit for a mobile telephone is capable of operations in either of two modes, i.e. in a hands-free or a push-to-talk mode. A constant current circuit is coupled in parallel with the microphone to preclude a change in a DC bias voltage responsive to switch operations, especially in a push-to-talk mode. A voltage comparator compares the bias voltage with a reference to detect control signals and selects a preferred mode of operation.

Abstract: This invention provides a switched limiter with variable attenuation designed with monolithic GaAs p-i-n diodes. Greater than 30 dB of small-signal variable attenuation is achieved at X band frequencies, with a minimum insertion loss of 0.5 dB. The variable attenuation switched limiter provides 15 dB of isolation to a +30 dBm input signal. Under bias conditions that result in variable attenuation the variable attenuation switched limiter input impedance remains matched. When used as a passive limiter, 7 dB of limiting has been achieved for a +30 dBm input signal at 10 GHz.

Abstract: A combined duplexer/mixer especially for use in an FMCW millimetric radar system has a waveguide section containing a fin line or suspended strip structure for responding to the linearly polarized radar return signal passing through the section in one direction while permitting passage of the orthogonally polarized, outgoing signal passing in the other direction. The fin line is coupled via double balanced mixer diodes to an IF output line to produce an IF signal by mixing the return signal with a portion of the outgoing signal tapped off by a field distorting probe, ridge section or like coupling means.

Abstract: A power limiter circuit for a radio frequency transceiver of the type having a single input-output antenna port is comprised of an isolator, first and second three port circulators and a pair of PIN diodes. One port of the first circulator is connected to the antenna port and one port of the second circulator is coupled to a transmit/receive antenna. The second ports of the two circulators are connected together through the isolator for passing signal from the transceiver to the antenna and the third ports of the two circulators are connected together for passing signal from the antenna to the transceiver. The PIN diodes, arranged in inverse parallel relationship, are connected between the third ports and circuit ground and operate in connunction with the isolator to limit to a safe value the signal passed from the antenna to the transceiver.

Abstract: Apparatus for processing microwave signals at two predetermined frequencies. Signals at a first predetermined frequency are received or transmitted at one end (input port) of a microwave transmission line whose other end is utilized as a common output port for transmitting and receiving signals at both predetermined frequencies. A band rejection portion is provided which comprises first and second rejection resonators orthogonally disposed along the transmission line at two predetermined positions. A bandpass portion, comprised of a plurality of collinearly aligned bandpass resonators, is disposed at a third predetermined position along the transmission line. Signals at a second predetermined frequency are transmitted or received at a second input port which is part of the bandpass portion. All resonators are capacitively coupled together and to the transmission line.

Abstract: A transmit-receive switching circuit is provided for switching a transmitter and a receiver to common antenna via a common signal path. A circulator is employed in the common signal path. The flow of transmitter RF energy and received RF energy is controlled through the circulator by a selectively actuable impedance element coupled to the circulator.

Abstract: A radar receiver protector having high isolation and low insertion losses due to a unique microwave assembly configuration is disclosed. The receiver protector includes at least one high power input protection stage and a sensitivity time controlled multi-level attenuation which together achieve rapid switching with a non-critical bias supply and circuit configuration and develop attenuation levels which are invariant with temperature and insensitive to diode parameters.

Abstract: A single terminal for a radio transmitter and receiver is connected to a first antenna for transmitting, and simultaneously to the first antenna or a second antenna for receiving. The connection is provided by a three port circulator having a first port connected to the first antenna, a second port connected through a quarter wavelength transmission line to a PIN diode and the second antenna, and a third port connected to the radio terminal. The radio transmitter is normally connected to the first antenna through the circulator, and the first or the second antenna is selectively and simultaneously connected to the radio receiver depending upon the conductive condition of the PIN diode.

Abstract: An electrically and mechanically modular design of a high impedance, passive tap is disclosed for use in distributed, serial transmission systems to provide a tap connection to the primary transmission line with minimum loading and reflection. The tap is comprised of the cable connectors and a microstrip circuit compatible with an associated transceiver.

Abstract: PIN diodes of decreasing base region thicknesses, wherein the thickest base region diode functions as a quasi-active limiter with turn-on bias supplied by detected RF current in a Schottky barrier diode with a discharge resistor providing fast recovery; and the thinnest base region PIN diode being a zero bias punch-through type, with a dc sensitivity time control, functioning as a passive limiter during transmit and controlled attenuator during receive provides an improved radar receiver protector circuit. The operation of the PIN diode is enhanced by a unique mounting on a gold-plated copper puck in the circuit board and tuning the signal leads to the diode.