Abstract:
Multiple radio channel frequency signals that are modulated with respective information modulation are transmitted from a common antenna at multiple radio frequencies. Multiple modulators are provided, a respective one of which corresponds to a respective one of the radio channel frequencies. Each modulator generates at least one constant amplitude, phase modulated drive signal at the corresponding radio channel frequency from the respective information modulation, such that the at least one constant amplitude, phase modulated drive signal corresponds to the information modulation for the corresponding radio frequency. At least one saturated power amplifier is provided for each of the at least one constant amplitude, phase modulated drive signals. A respective saturated power amplifier is responsive to the corresponding constant amplitude, phase modulated drive signal, to produce a corresponding amplified output signal at an output thereof. A coupling network connects the outputs of the saturated power amplifiers in series, to produce a combined signal that is applied to the common antenna, such that the common antenna radiates the radio channel frequency signals that are modulated with the respective information modulation. In first embodiments, the at least one constant amplitude, phase modulated drive signal is a single constant envelope modulation drive signal, wherein the information modulation is a constant envelope information modulation. In other embodiments, at least two constant amplitude phase modulated drive signals are provided at the corresponding radio channel frequency, such that the at least two constant amplitude, phase modulated drive signals correspond to the information modulation for the corresponding radio frequency.
Abstract:
The present invention provides a low-cost, steerable antenna (100) formed with a dielectric medium (102) separating a pair of conductive plates (104, 106) and a centrally located signal feed (114). Switches selectively interconnect the conductive plates through the dielectric medium in patterns, which determine the direction of operation of the antenna. The directionality of the antenna may be fixed or rapidly changed, depending upon the application.
Abstract:
A method utilizes a training monitoring algorithm (Fig. 10) to control when full training of a transmitter of a shared communication system that utilizes dynamic channel allocation occurs. Full training of the transmitter occurs during an initial transmission slot of a training interval that is used to request allocation of fixed communication resources of the communication system or when operating conditions of the transmitter, such as power and frequency, change. The duration of the training interval is dynamically controlled by manipulation of full-power and cut-back power training interval counters.
Abstract:
The present invention addresses the need for an apparatus and method for controlling the load of a PA, to improve PA efficiency in linear transmitters with isolator elimination (IE) circuitry, that does not require the use of high frequency RF circuitry. The present invention provides a PA load controller (130, 131) that improves the efficiency of a PA (116) by adjusting the PA load using an AGC signal (134), a level set adjustment signal (132), and a signal strength indicator (135), these three signals are readily obtained from continuous gain and phase adjustment circuitry (e.g., 102). The load controller determines a phase of the PA load that minimizes the AGC signal and a phase of the PA load that maximizes the level set adjustment signal. From these determinations, the PA load controller determines a phase of the PA load that improves the efficiency of the PA and adjusts the PA load phase accordingly.
Abstract:
A multiple loop antenna (70) is provided which may be connected to either a transmit circuit, a receive circuit, or a transmit/receive circuit (80). When powered by a transmit circuit (60), the antenna (70) generates radio frequency magnetic fields in an area or zone proximate to the antenna, but which are substantially canceled at a distance approximately one wavelength and more from the antenna (70), thereby defining a surveillance zone proximate to the antenna (70). The loop antenna (70) includes a first, upper loop (36) and a second, lower loop (38). The upper (36) and lower (38) loops lie in separate, spaced, parallel planes and are preferably disposed at a fixed angle with respect to the surveillance zone.
Abstract:
A modulator loop (700) designed to operate in a frequency range of interest is described. The loop (704) includes a loop output terminal and a switching stage, the output of which is coupled to the loop output terminal. The switching stage (704) has a first delay associated therewith. The output of a modulator stage is coupled to the input of the switching stage. A first feedback path is coupled between the loop output terminal and the feedback input of the modulator stage. A feedback filter is coupled between the output of the modulator stage and the feedback input of the modulator stage which compensates for the first delay. The feedback filter (708) is operable to transmit frequencies outside the frequency range of interest and attenuate frequencies in the frequency range of interest.
Abstract:
An RFID circuit for incorporation in an identification device which includes a polymeric substrate (12), the circuit being formed or integrally connected with said substrate whereby the substrate becomes a component of the RFID circuit. An embodiment of the circuit includes circuit elements (10, 14) printed or attached to opposite sides of the substrate utilizing the resistance of the substrate in a reactive or inductive circuit.
Abstract:
A variety of methods for fabricating organic photovoltaic-based electricity-generating military aircraft fuselage surfaces are described. In particular, a method for fabricating curved electricity- generating military aircraft fuselage surfaces utilizing lamination of highly flexible organic photovoltaic films is described. High-throughput and low-cost fabrication options also allow for economical production.
Abstract:
A method for fabricating organic photovoltaic-based electricity-generating military pilot equipment, including flight suits, helmets, helmet visors, and related equipment is described. In particular, a method for fabricating such equipment utilizing lamination of highly flexible organic photovoltaic films is described. High-throughput and low-cost fabrication options also allow for economical production.