Importance

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Abstract

A passive reflective antenna located near an active receiving antennas is used to change the energy at the receiving antenna. The change in energy may be such as to remove a null created by multipath or to provide directionality, or both. The receiving antennas is permanently connected to a single receiver. When the receiver's output signal degrades below an acceptable level of quality, the reflective phase of the passive antenna's load is changed to change the phase of the reflected energy and achieve a desired effect (remove a null, change directionality, etc.) at the receiving antenna. In the simplest embodiment, the termination of the passive antenna is switched from an open circuit to a short circuit, or vice versa, to invert the phase of the reflected energy. The use of reflective elements in antenna designs, usually to achieve directionality, is well known (see the common Yagi or corner reflector antenna designs, for example), but these use passive reflector elements. The present invention, in contrast, employs active control of the reflective element. The term 'reflective element' is used to mean an element that re-radiates RF energy. The position of a reflective element relative to the active receiving antenna (whether the reflective element receives RF energy from a waveform and before or after the active receiving antenna) is unimportant, so long as a portion of the re-radiated energy is picked up by the active receiving antenna and the phase with which the re-radiated energy is received is controllable.

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First Claim