Abstract: A multi-port antenna and associated systems having extremely wide bandwidth and capable of maintaining directivity as frequency decreases and is made arbitrarily low, allowing DF systems to operate to arbitrarily low frequency regardless of size. Construction may be rugged, lightweight, and low cost, allowing reliable service in harsh environments. The systems allow utilization of both the E and H fields occupying a common area of space. The disclosed DF system takes advantage of knowledge of the as-installed array manifold, uses pattern matching to determine the angle of arrival (AoA) of incoming waves, and enhances sensitivity by using integration on cross-correlation products between the multiple ports to achieve SNR improvement.

Abstract: A multiport antenna in which the antenna conductive elements are arranged to form an at least partially enclosed volume which can accommodate an enclosure containing one or more electronic components, or optical components, or optoelectronic components, or a combination of these. The enclosure may also be provided with a conductive transparent window which permits optical components to receive and/or send optical information.

Abstract: Apparatus for and method of using derived information about the direction of propagation of an incoming radar beam to control radar return. The information about the direction of propagation of the incoming radar beam is used to alter aspects of a platform's orientation to control the cross section presented to the radar.

Abstract: The present invention provides a method and apparatus for monitoring a trunked radio communications system by using some type of radio scanning receiver that is not designed for that purpose. In addition, the invention provides a method for automatically determining the polarity of the received control channel data. Further, the invention provides a method for automatically determining the type of trunked radio communications system. In addition the invention provides a method for automatically determining the channels in a trunked radio system and a method for automatically determining the bit rate of transmitted digital signals over a control channel of a trunked radio communications system.