Abstract: A radial power divider-combiner is disclosed. Such a radial divider-combiner may include a plurality of waveguides, each of which extends between a central monopole antenna and a respective peripheral monopole antenna. Such a waveguide may have a central portion with a height-to-width ratio of two, and a peripheral portion having an aspect ratio of one. To improve impedance-matching, a transformer portion may be disposed between the central portion and the peripheral portion. Such a transformer portion may have any number of sections, from one to infinity, with each section having a respective height between that of the central portion and that of the peripheral portion. In the extreme case, where the number of “sections” is infinite, the height of the transformer portion may vary linearly from that of the central portion and that of the peripheral portion.

Abstract: A radial power divider-combiner is disclosed. The divider-combiner includes a divider and a combiner. An input signal is provided to a transmission antenna that radiates the input signal inside the divider. Within the divider, the input signal is divided into a plurality of individual signals. The individual signals are received by receiving antennas and provided to respective amplifiers. The amplifiers amplify the respective individual signals by a desired amplification factor. The amplified individual signals are provided to a plurality of transmitting antennas within the combiner. Inside the combiner, the amplified individual signals are combined to form an output signal that is received by a receiving antenna in the combiner.

Abstract: A radial power divider-combiner is disclosed. Such a radial divider-combiner may include a plurality of waveguides, each of which extends between a central monopole antenna and a respective peripheral monopole antenna. Such a waveguide may have a central portion with a height-to-width ratio of two, and a peripheral portion having an aspect ratio of one. To improve impedance-matching, a transformer portion may be disposed between the central portion and the peripheral portion. Such a transformer portion may have any number of sections, from one to infinity, with each section having a respective height between that of the central portion and that of the peripheral portion. In the extreme case, where the number of “sections” is infinite, the height of the transformer portion may vary linearly from that of the central portion and that of the peripheral portion.

Abstract: A radial power divider-combiner is disclosed. The divider-combiner includes a divider and a combiner. An input signal is provided to a transmission antenna that radiates the input signal inside the divider. Within the divider, the input signal is divided into a plurality of individual signals. The individual signals are received by receiving antennas and provided to respective amplifiers. The amplifiers amplify the respective individual signals by a desired amplification factor. The amplified individual signals are provided to a plurality of transmitting antennas within the combiner. Inside the combiner, the amplified individual signals are combined to form an output signal that is received by a receiving antenna in the combiner.

Abstract: A radial power divider-combiner is disclosed. The divider-combiner includes a divider and a combiner. An input signal is provided to a transmission antenna that radiates the input signal inside the divider. Within the divider, the input signal is divided into a plurality of individual signals. The individual signals are received by receiving antennas and provided to respective amplifiers. The amplifiers amplify the respective individual signals by a desired amplification factor. The amplified individual signals are provided to a plurality of transmitting antennas within the combiner. Inside the combiner, the amplified individual signals are combined to form an output signal that is received by a receiving antenna in the combiner.

Abstract: A radial power divider-combiner is disclosed. The divider-combiner includes a divider and a combiner. An input signal is provided to a transmission antenna that radiates the input signal inside the divider. Within the divider, the input signal is divided into a plurality of individual signals. The individual signals are received by receiving antennas and provided to respective amplifiers. The amplifiers amplify the respective individual signals by a desired amplification factor. The amplified individual signals are provided to a plurality of transmitting antennas within the combiner. Inside the combiner, the amplified individual signals are combined to form an output signal that is received by a receiving antenna in the combiner.

Abstract: A radial power divider-combiner is disclosed. The divider-combiner includes a divider and a combiner. An input signal is provided to a transmission antenna that radiates the input signal inside the divider. Within the divider, the input signal is divided into a plurality of individual signals. The individual signals are received by receiving antennas and provided to respective amplifiers. The amplifiers amplify the respective individual signals by a desired amplification factor. The amplified individual signals are provided to a plurality of transmitting antennas within the combiner. Inside the combiner, the amplified individual signals are combined to form an output signal that is received by a receiving antenna in the combiner.

Abstract: A radial power divider-combiner is disclosed. The divider-combiner includes a divider and a combiner. An input signal is provided to a transmission antenna that radiates the input signal inside the divider. Within the divider, the input signal is divided into a plurality of individual signals. The individual signals are received by receiving antennas and provided to respective amplifiers. The amplifiers amplify the respective individual signals by a desired amplification factor. The amplified individual signals are provided to a plurality of transmitting antennas within the combiner. Inside the combiner, the amplified individual signals are combined to form an output signal that is received by a receiving antenna in the combiner.

Abstract: In accordance with the present invention, a general antenna system is disclosed suitable for applications in which an RFID Tag passes by an Interrogator. We then disclose a specific antenna design that uses a single planar antenna for transmit and a multi-element planar antenna array for receive. The multi-element planar antenna array is spaced such that each of the planar elements is four inches apart, center-to-center, thus defining a narrow 30° receive beamwidth in the horizontal plane. The vertical receive bandwidth is much greater than 30°, facilitating the Interrogator receiving signals at a variety of elevations. Furthermore, a multi-way microstrip combiner is used to sum the signals received from each of the planar antennas. To block interference from the transmit antenna and to improve receive sensitivity, this multi-way microstrip combiner is shielded using, in one embodiment, copper tape along its edges. In a specific embodiment, a four element receive antenna design is disclosed.

Abstract: In accordance with the present invention, an RFID system has a homodyne receiver having two outputs; the in-phase or I output and the quadrature or Q output. The modulated backscattered signal is composed of an information signal, modulated onto a single frequency subcarrier signal, generating a modulated subcarrier signal; this modulated subcarrier signal is then backscatter modulated onto the incoming RF signal. To demodulate this modulated backscattered signal, the I and Q outputs are combined using an IQ combiner. This IQ combiner introduces a 90.degree. phase shift, with respect to the frequency of the subcarrier signal, onto one of the demodulator outputs and then combines the outputs of the demodulator.

Abstract: Methods and apparatus for variably converting DC voltage to a different DC voltage level are effected by a multi-resonant electronic power converter with a wide output voltage dynamic range. The power conversion is accomplished by converting the DC voltage to an AC signal, adjusting or attenuating the AC signal to the desired amplitude, and then converting the AC signal back to a DC voltage. The output voltage may be adjusted by altering the frequency of the AC signal also known as the switching frequency. A wide dynamic range is achieved at a narrow switching frequency bandwidth by inserting either a fourth or higher order low pass filter or a notch filter at the output of the switching transistor. The high roll-off rate exhibited by either filter provides a relatively high dynamic range in a narrow frequency range.

Abstract: Methods and apparatus for variably converting a DC voltage to a different DC voltage level are effected by a multi-resonant electronic power converter with a wide output voltage dynamic range. The power conversion is accomplished by converting the DC voltage to an AC signal, adjusting or attenuating the AC signal to the desired amplitude, and then converting the AC signal back to a DC voltage. The output voltage may be adjusted by altering the frequency of the AC signal also known as the switching frequency. A wide dynamic range is achieved at a narrow switching frequency bandwidth by inserting either a fourth or higher order low pass filter or a notch filter at the output of the switching transistor. The high roll-off rate exhibited by either filter provides a relatively high dynamic range in a narrow frequency range.

Abstract: An unbalanced quadrature phase-shift keyed UQPSK modulator modulates two information signals onto mutually quadrature components of a carrier. If the carrier components differ from an exact quadrature relationship by an error angle, crosstalk orr distortion is introduced. The effects of such an error are ameliorated by a limiter following the modulator.

Abstract: The present invention relates to a transition wherein a microstrip line, formed on one major surface of a substrate, is capacitively coupled to a reduced-height waveguide, comprising a predetermined width-to-height ratio, by means of a T-bar conductive pattern formed on a substrate at the end of the microstrip line. Such T-bar transitions can also be connected on opposite end of the microstrip line to provide connections between two waveguide sections.

Abstract: An unbalanced quarternary phase-shift keying modulator provides relatively higher signal power for one of two signal information channels. The carrier to be modulated is split into two equal-amplitude, equal-phase portions, each of which is applied to a biphase modulator. Each of the information signals is also applied to one of the biphase modulators, for producing two equal-amplitude, phase modulated carriers, each biphase modulated by one of the information signals. The modulated carriers are applied to the ports of a quadrature hybrid coupler which is other than a 3 dB (equal-amplitude) coupler. In one embodiment, the coupler is a 7 dB coupler. The modulated carrier applied to the through port of the coupler appears with reference amplitude and phase at the output of the hybrid. The modulated carrier applied to the other or coupled port appears at the output with relatively reduced amplitude and a relative phase shift. In one embodiment, the phase shift is 90.degree..

Abstract: A waveguide-to-coax-to-microstrip transition includes a rectangular waveguide portion having a ridged impedance transformer attached to the lower wide wall. The waveguide portion is closed off by a conductive wall through an aperture in which the center conductor of a coaxial transmission-line passes. A ridge extension isolated from all four walls of the rectangular waveguide couples the ridge to the center-conductor of the coax. For broadbanding, a glass plate is located between the ridge extension and the upper wide wall. The strip conductor of a microstrip transmission-line is connected to the center conductor of the coaxial transmission-line. The plane of the dielectric plate of the microstrip may be oriented parallel to the narrow wall of the rectangular waveguide to achieve high packing density.

Abstract: A planar Y-junction microwave circulator formed by depositing on a ferrite substrate a metallization pattern consisting of a central resonant disc and three transmission line ports radially extending from the periphery of the disc at junctions spaced apart by 120.degree.. The transmission characteristics of the circulator are controlled by a DC magnetic field which biases the ferrite. Wide-band operation on the order of one octave is achieved by using larger port coupling angles and a smaller disc radius than are conventionally used.