Abstract: A voltage controlled push-push oscillator is provided having a variable frequency output over a range of frequencies. Usually, the range of frequencies is in the microwave range. The configuration is such that the collectors of a pair of transistors are tied together, and an inductive reactance is provided across the base and collector of each of the transistors, with the emitters of the pair of transistors being each connected to opposite phases (at the fundamental frequency) of a resonator which may comprise of one or more elements, bisected to provide an output tap at which an RF null at the fundamental frequency and an anti-null at the second harmonic exists, whereby the second harmonic output frequency of the push-push oscillator is derived. Particularly when the push-push oscillator operates at microwave frequencies, the resonator element is a microstrip line, having the output tap at the centre thereof.

Abstract: The invention concerns radar detectors which are capable of monitoring at least two frequency bands. A broad band antenna is provided, together with a mixer comprising an anti-parallel pair of diodes, and at least one local oscillator. The local oscillator frequency is mixed with radar frequency from the antenna to produce an intermediate signal which is amplified further down converted detected and fed to signal processing circuitry to actuate an alarm when radar frequency of interest is detected. The most effective mixing with the RF input takes place at twice the local oscillator frequency. By application of direct current bias to the mixer, the most effective mixing with the RF input is changed to occur at the local oscillator frequency. The local oscillator is used to monitor two different radar frequencies by application and non-application of DC bias to the mixer. For multiband detectors, more than one local oscillator may be used.

Abstract: The invention concerns radar detection devices sensitive to signals from various different frequency bands. A broad band antenna is provided, together with a mixer and a plurality of local oscillators. Signals from the local oscillators are mixed one at a time with signals from the antenna, there being one local oscillator signal for each radar frequency or pair of frequencies of interest which may be received by the antenna. Each local oscillator signal is chosen so that when it is mixed with the respective radar frequency signal, an intermediate signal is produced which is the same for all mixtures. This intermediate signal is further down converted and fed to signal processing circuitry to produce an alarm when radar frequencies of interest are detected.

Abstract: The invention concerns a radar detection device--particularly a radar detection for police radar--which is improved with regard to undesirable microwave emissions therefrom. For the X-band and the K-band, for example, two horn antennae are provided, each associated with a local oscillator. A mixer is provided to mix signals from each horn antenna and from its respective local oscillator. Each antenna is made specific to radar signals within its respective band, and precautions are taken to avoid emission of K-band radiation from the larger X-band horn. For example, a bandpass filter for X-band radiation may be used in a feed line branch to the mixer from the X-band horn. The K-band radiation may be fed through in a feed line branch approaching the mixer from an opposed direction.

Abstract: Radar detection and signal processing circuits are provided where, following a front end having an RF and local oscillator mixer to an I.F., which is then further mixed against a signal from a swept frequency oscillator, in the presence of a microwave frequency signal, the output of a band pass filter goes to a detector for frequency modulated intermediate frequency signals, and that detector has at least a first output signal that is fed to two pairs of complementary paired comparators, the outputs of which are set to low and high threshold levels. The first pair of complementary comparators has a low threshold level output which is examined by a microprocessor for the incidence of detected low threshold signal in a number of spaced cells--as determined by a clock which divides the detector output into time cells of the sweep period of the swept oscillator. Signal processing is provided so that the incidence of signals in a pair of spaced cells over a given number of consecutive sweeps causes an alarm.

Abstract: A radar detector assembly is provided for portable installation in an automotive vehicle--that is, for detachable attachment within the vehicle--where a substantial portion of the front face of the body of the radar detector is covered with a mirror, and the back face is provided with fastening means to detachably attach the radar detector to the mirror which is permanently installed in the vehicle. Within the body of the radar detector is a microstrip antenna for reception of microwave frequency radar signals, and the microstrip antenna is located within the body of the radar detector at a place where the front face of the body is not covered by the mirror, and the back face of the body is not proximate to the vehicle mirror.

Abstract: A horn antenna construction, particularly for use in microwave radar detector circuits, comprises a molded horn element that is open at its bottom side, with a ridge molded into its flared top surface, and being electrically conductive at least at microwave frequencies such as in the X-band and K-band. The open bottom of the horn element mates to a conductive upper surface on a mounting board, and the horn is drawn down onto the mounting board so that its upper surface forms the bottom of the horn. Thus, the ridge is brought into physical and electrical contact with a feed strip formed in a microstrip board on the mounting board, that has a mixing diode or diodes associated therewith. By this construction, there is a positive and dimensionally stable association of the throat of the horn and the ridge to the feed strip and the mixing diode(s), without the necessity of any solder, inserted connectors or mounting pins, or the provision of any tuning posts or screws.