Abstract: A radio frequency switch which has input and output diodes and a quarter length impedance inverter interconnecting the diodes. A switch drive signal is clamped to a predetermined voltage between drive signals so that the impedance with respect to the input source remains substantially constant during the entire switch operation.

Abstract: Movement of an object (intruder) in a specified area is sensed by transmitting microwave energy from an antenna (10) that also receives energy reflected from the intruder, where the received energy is quadrature processed using Doppler techniques. Connected to the antenna (10) is a transceiver (12) that includes a quadrature mixer (48) coupled to an RF oscillator (50) through an RF switch (52). The RF switch (52) is controlled by a switch driver (54) to provide pulse energy from the antenna (10). Doppler outputs E.sub.1 and E.sub.2 from transceiver (12) are processed in the same manner except for a 90-degree phase lead applied to the Doppler output E.sub.2 by a phase lead network (18). Doppler outputs E.sub.1 and E.sub.2 (E.sub.2 90-degree phase shifted) are applied simultaneously to a sum and signature processor (24) and to a difference and signature processor (22). The sum and signature processor provides the "approach" receiving signal and processes the signature to further reduce the nuisance alarm rates.

Abstract: A resonant radiation assembly for RF transmission lines is provided wherein the coupling level between the assembly and the transmission line may be readily adjusted at any point along the longitudinal axis of the line. The outer conductor of a coaxial transmission line is partially milled to provide radiation slots along the line, and the conductor is sheathed in a polyethylene cable jacket. A section of dielectric tubing is longitudinally gapped. Either plural conductive strips in combination with a transversely oriented radiation loop, or a single conductive strip is bonded to the outer surface of the tubing opposite the gap. The tubing is placed over the jacket and translated along the line to the desired operating location. The RF coupling level may be adjusted by rotating the tubing about the transmission line to vary the degree of coincidence between the conductive strip and the radiation slots.

Abstract: A flexible line distributed antenna, defining a perimeter of interest, radiates energy supplied from a transceiver. Motion around the flexible line causes the reflected energy which is intercepted by the flexible distributed antenna to be coupled back to the transceiver as a doppler frequency for processing in an alarm system. Reflected energy from the antenna to the transceiver is amplified and rectified into a DC voltage. This DC voltage is integrated to produce a time varying signal to a level detector that responds to a predetermined value of the integrated DC voltage. A response by the level detector provides an actuating signal to an alarm indicator through alarm logic. Ambient conditions around the extended flexible line distributed antenna are monitored by external sensors having outputs for controlling amplifier gain and triggering the alarm logic. For improved motion detection reliability, reflected energy from the antenna is coupled to a transceiver providing two output signals.