Abstract: The present invention is directed to an antenna system that includes a broadband free-space antenna (i.e., an antenna that does not utilize a ground plane to create a resonant structure) and a high-impedance backing that allows the antenna to be positioned adjacent to a conductive surface that but for the high impedance backing would adversely affect the broadband operation of the antenna. The high-impedance backing substantially preserves the bandwidth of the antenna while also allowing the antenna to be positioned within ?/4 of the conductive surface and accommodate a predetermined amount of power.

Abstract: A low-profile lens element for steering a beam is provided. Specifically, the low-profile lens element is mechanically rotatable such that a beam can be steered in any direction within three-dimensional space. The lens element may include a number of discrete portions for differentially delaying adjacent discrete portions of a beam in order to effect beam steering.

Abstract: A low-profile lens element for steering a beam is provided. Specifically, the low-profile lens element is mechanically rotatable such that a beam can be steered in any direction within three-dimensional space. The lens element may include a number of discrete portions for differentially delaying adjacent discrete portions of a beam in order to effect beam steering.

Abstract: A phased array type antenna apparatus compensates for phase and time differences between signals received at different elements of the antenna. Each element within the antenna apparatus has an associated phase/time adjuster circuit. The signals from each element are divided, with the first output routed to a combining circuit. The second output of one element is used as a reference signal, with the second output from the remaining elements routed to a switch. One signal is selected at the switch, and is used as a non-reference signal. Phase difference between the reference signal and the non-reference signal is determined at a comparator circuit, and the phase/time adjuster circuit associated with the non-reference signal is adjusted to bring the two signals into phase alignment. Time difference between the reference and non-reference signal is determined using dual correlators and a comparator circuit.

Abstract: A phased array type antenna apparatus compensates for phase and time differences between signals received at different elements of the antenna. Each element within the antenna apparatus has an associated phase/time adjuster circuit. The signals from each element are divided, with the first output routed to a combining circuit. The second output of one element is used as a reference signal, with the second output from the remaining elements routed to a switch. One signal is selected at the switch, and is used as a non-reference signal. Phase difference between the reference signal and the non-reference signal is determined at a comparator circuit, and the phase/time adjuster circuit associated with the non-reference signal is adjusted to bring the two signals into phase alignment. Time difference between the reference and non-reference signal is determined using dual correlators and a comparator circuit.

Abstract: The present invention relates to a wireless transponder system. The transponder system includes a transponder device which is capable of operating over a relatively long range without the need for frequent battery replacements. The transponder device includes both an antenna means and a signal modification means. The signal modification means is operative for modulating an interrogation signal received from a reader device. The modulation means may utilize low power switching components that allow it to operate continuously while drawing very little current from an internal battery. In this way, the battery within the transponder will not become prematurely drained and can last up to substantially the shelf-life of the battery. In one embodiment, the transponder of the present invention utilizes a retrodirective array antenna for achieving increased antenna gain in the direction of a reader device, and therefore increased range, without an associated reduction in effective antenna coverage.