Abstract: A microwave frequency discriminator circuit useful as a frequency lineariion device includes a microstrip input conductor and a pair of microstrip output conductors, a pair of resistors, a pair of microstrip transmission line diplexer stubs of unequal lengths, a pair of detector diodes, and a quad of microstrip filter stubs. Each resistor at one end is connected to the same end of the input conductor and in parallel relation to one another. Each diplexer stub at one end is connected to an opposite end of one resistor and in parallel relation to one another. Each diplexer stub is open-circuited at an opposite end. Each detector diode at one end is connected to the one end of one stub and at an opposite end to one output conductor. The filter stubs are interposed in spaced pairs in one output conductor.

Abstract: An array antenna system has been described incorporating a plurality of antenna elements each having two quarter wave patches or monopoles for radiating microwave energy in a forward and reverse direction, a first and second beam forming network coupled to a coupler for each antenna element, wherein microwave energy coupled to the antenna element from one beam forming network couples lagging phase to one of the two quarter wave patches and from the second beam forming network couples lagging phase to the other quarter wave patch. The invention overcomes the problem of antenna utilization by providing two autonomous beam patterns with independent control or for overcoming the problem of antenna pattern performance by providing a second pattern which may be combined with the first pattern to provide, for example, an improved front-to-back ratio.

Abstract: An first antenna for radiating a signal at a predetermined frequency employing at least one 1/4 wave-length microstrip resonator positioned below a metal 1/4 wavelength radiator. A circularly polarized antenna including a 1/2 wavelength radiator electromagnetically coupled to a 1/4 wavelength resonator is further disclosed.

Abstract: A first antenna for radiating a signal at a predetermined frequency employing at least one 1/4 wavelength microstrip resonator positioned below a metal 1/4 wavelength radiator. A circularly polarized antenna including a 1/2 wavelength radiator electromagnetically coupled to a 1/4 wavelength resonator is further disclosed.

Abstract: A beam forming network for a circular array antenna includes a sum pattern network for generating signal weights corresponding to a sum antenna pattern having omnidirectional sidelobes and a difference pattern network for generating signal weights corresponding to a difference antenna pattern with omnidirectional sidelobes. Means are provided to couple energy from the difference pattern network to the sum pattern network. The signal weights are split by signal splitters and delivered in pairs to output terminals, one of which is terminated in its characteristic impedance.

Abstract: An antenna element is comprised of two rectangular microstrip patch dipoles spaced by dielectric a predetermined distance above a ground plane conductor. One edge of each dipole is electrically shunted to the ground plane conductor. The dipole feedpoints are separated by a quarter wavelength of the antenna resonant frequency. An isolated power splitter and phase shifter connects an antenna element port with the dipole feedpoints so that the signal at one feedpoint lags the signal at the other feedpoint by 90.degree.. The antenna element will end fire through the dipoles in the direction of the lagging signal feedpoint.A low profile circular array antenna is comprised of eight such antenna elements arranged on the ground plane conductor equally spaced with their phase centers on a common phase center circle.

Abstract: The diode bias input terminals of an IMPATT microwave power combiner are resistively coupled to a common floating node to provide stabilization of the operating points of the individual IMPATT diodes, thus minimizing the tendency of the diodes to contribute unequally to total RF output, particularly in a varying temperature environment. The optional inclusion of RF lossy bypass capacitors to ground several points of the common node suppresses bias circuit oscillations.

Abstract: A timing circuit (20, 22, 24) for use with a pulsed solid state radar generates signals which are applied to a pulse forming circuit (33) to provide preheat and immediately subsequent thereto current drive pulses applied to IMPATT diodes which in response thereto generate RF signal pulses (10, 12) having reduced chirp and level variations. The pulses are formed by transistors (70, 74) which are rendered conductive when their current return paths (28, 38) are established through resistors (34, 44) whose values determine the levels of the preheat and drive pulses.The duration of the preheat pulse is made responsive to ambient temperatures by using a negative-temperature-coefficient thermistor (86) as the time determining element of the timing circuit. The level of the preheat pulse is made responsive to ambient temperature by using positive-temperature-coefficient silicon thermistors (34) in the above mentioned current return path.

Abstract: AM noise produced by a CW or FM-CW radar transmitter can be cancelled from the radar receiver output by use of a servo system working at video frequencies. A fixed pair of AM sidebands is deliberately added to the source, using a known discrete modulating frequency. A demodulated sample of the total AM noise produced by the source is obtained from a single ended mixer. The servo system adjusts the gain of an amplifier processing this noise, until the level of the demodulated test signal is equal to the level of the demodulated test signal at the output of the radar receiver. The two video signals are then subtracted, cancelling the test tone from the receiver output and incidentally also cancelling the AM source noise from the output of the system.