Abstract: A synthetic aperture radar's surveillance is defeated by electronic camouflage that employs a protective shield to cover an intended target. The shield intercepts and modifies the interrogating radar pulses by modulating incident radar pulses to produce radar echoes shifted in Doppler frequency, whereby the returned echoes give a false depiction of the target, even to smearing the radar display. New structures are presented that exhibit variable reflectivity and variable dielectric characteristics of particular use in the foregoing and other electronic systems.

Abstract: Novel test mounts are defined for a radar cross section testing apparatus that allows a supported object to be tested without interference from the test mount. This includes prescribing a diameter of about 0.61 wavelegths for a cylindrical test mount; maintaining a ratio for the test mount's characteristic dielectric constant and magnetic permeability of about one; and/or installing a frequency transposing apparatus to convert the frequency of radar pulses directed toward the test mount to off-frequency echoes.

Abstract: Microwave devices incorporate at least one photosensitive baffle that is selectively illuminated changing the baffle's electronic characteristic from being transparent to being reflective of microwave energy. The baffle serves as a gate, tuning element, reflector and the like. Various forms of photosensitive baffles and microwave devices are presented.

Abstract: Novel test mounts are defined for a radar cross section testing apparatus that allows a supported object to be tested without interference from the test mount. This includes prescribing a diameter of about 0.61 wavelengths for a cylindrical test mount; maintaining a ratio for the test mount's characteristic dielectric constant and magnetic permeability of about one; and/or installing a frequency transposing apparatus to convert the frequency of radar pulses directed toward the test mount to off-frequency echoes.

Abstract: Microwave devices incorporate at least one photosensitive baffle that is selectively illuminated, changing the baffle's electronic characteristic from being transparent to microwave energy to being reflective thereof. That action selectively alters an electronic characteristic of the microwave device. The effect is shown applied in a number of devices, including a back lobe antenna. Undesired back lobes occuring at a principal frequency are reduced in a back plane antenna by alternately coupling and decoupling an extension to the antenna's back plane at a rate sufficiently high enough to shift the back lobes to adjacent frequencies. A photoelectrically controlled baffle suitably serves as the extension.