Abstract:
A radio-frequency amplifier (50) has an impedance transformation network (66) with a control input (70) for controlling the transformation characteristic of the transformation network (66). The radio-frequency amplifier (50) amplifies an input signal to produce an amplified radio-frequency output signal to a load (68). The control circuit selects a power level for the output signal, in response to a control signal, by transforming the impedance of the load to a transformed impedance at the output of the radio-frequency amplifier, so that the efficiency of the radio-frequency amplifier is not substantially degraded as the power level for the output signal is changed.
Abstract:
An acknowledge back (ack-back) paging system is provided which includes a central station which transmits a group of message signals to an group of ack-back pagers which are addressed as a group. The users of the group of addressed ack-back pagers indicate a response to their respective pagers thus providing ack-back data. The pagers in the group of addressed ack-back pagers then simultaneously transmit back to the central station their ack-back signals using different respective pseudorandom codes, a different pseudorandom code being dynamically allocated to each of the pagers in the group.
Abstract:
An acknowledge back (ack-back) paging system is provided which includes a central station which transmits a group of message signals to a group of ack-back pagers which are addressed as a group. The users of the group of addressed ack-back pagers indicate a response to their respective pagers thus providing ack-back data. The pagers in the group of addressed ack-back pagers then simultaneously transmit back to the central station their ack-back data on different frequency sub-bands, a different frequency sub-band being allocated to each of the pagers in the group.
Abstract:
An balun/antenna apparatus is provided which is capable of being fabricated on a printed circuit board substrate by automated equipment. The balun-antenna includes a microstrip groundplane conductor which is split into two balanced ground arms at one end. The split groundplane conductor operates as both a balun and as a radiating conductor. A unique microstrip excitation structure is situated above the split ground elements on the opposed surface of the substrate to excite the antenna with radio frequency energy.
Abstract:
An acknowledge back (ack-back) pager is provide for use in a paging system which includes a central station which transmits a group of message signals to a group of ack-back pagers which are addressed as a group. The users of the group of addressed ack-back pagers indicate a response to their respective pagers thus providing ack-back data. The pagers in the group of addressed ack-back pagers then simultaneously transmit back to the central station their ack-back data on different frequency sub-bands, a different frequency sub-band being allocated to each of the pagers in the group. The invention provides apparatus for controlling the frequency of the selected sub-band with very high accuracy.
Abstract:
An balun-antenna arrangement is provided which is capable of being fabricated on a printed circuit board by automated equipment. The balun-antenna includes a microstrip transmission line which is coupled to one end of a split microstrip transmission line having opposed ends. An antenna which is symmetric about its feedpoint is coupled to the remaining end of the split microstrip transmission line.
Abstract:
A space efficient magnetic antenna is disclosed for use in tracking, positioning and other applications. In a preferred embodiment, a space efficient magnetic antenna system comprises a first magnetic antenna with a first null axis aligned within a predetermined plane and a second magnetic antenna having a second null axis aligned substantially orthogonal to a first null axis. A second magnetic antenna system lies in a minimal coupling orientation with respect to a first magnetic antenna system. Additionally, a first magnetic antenna may further comprise a plurality of interconnected magnetic antenna elements. A space efficient magnetic antenna system may include an RF module. In further embodiments, the antenna system may enclose a substantial majority of the device including the RF module; the RF module may be enclosed substantially or wholly within one or more antennas of the antenna system.
Abstract:
In one embodiment, a UWB transmission system includes a pair of crossed linearly polarized antennas, one of which is fed with a UWB signal current, while the second is fed with a temporally orthogonal UWB signal such as the time-derivative of the UWB signal current. The resultant elliptically polarized radiated fields are simultaneously orthogonal in space and orthogonal in time. In another transmission system, a loop and a co-located dipole are fed with the same current to generate signal exhibiting elliptical polarization. When the energies of the transmissions from each antenna are equal, the polarization is circular. Thus a UWB transmitting and receiving system is shown that utilizes signals that are simultaneously spatially orthogonal and temporally orthogonal, and the several combinations of those signal and polarization states encode data for transmission.
Abstract:
In one embodiment, a UWB transmission system includes a pair of crossed linearly polarized antennas, one of which is fed with a UWB signal current, while the second is fed with a temporally orthogonal UWB signal such as the time-derivative of the UWB signal current. The resultant field is elliptically polarized. In another transmission system, a loop and a co-located dipole are fed with the same current to generate signal exhibiting elliptical polarization. When the energies of the transmissions from each antenna are equal, the polarization is circular. In yet another embodiment, a polarization modulated transmitting and receiving system is disclosed in which the binary states are encoded in orthogonal polarizations, wherein left-handed polarization encodes one digital state while right-handed polarization encodes another digital data state, and data encoding is additionally provided. Since either one circular polarization state can be generated with both UWB pulses flipped in polarity, a Polarization Orthogonal Keying (POK) modulation, of 4-state per symbol in the two orthogonal polarizations is disclosed as one example. Thus a UWB transmitting and receiving system is shown that utilizes signals that are simultaneously spatially orthogonal and temporally orthogonal, and the several combinations of those signal and polarization states encode data for transmission.
Abstract:
An RF transmitter includes a reference signal generator, a signal generator, and a mixer. The reference signal generator provides a reference signal that has a prescribed or desired frequency. The signal generator provides an operating signal in response to a selection signal. The operating signal has a frequency that equals the frequency of the reference signal multiplied by a number. The mixer mixes the operating signal with another signal to generate a transmission signal. An RF receiver includes a first mixer, a second mixer, an integrator/sampler, and a signal generator. The first mixer receives as its inputs an input RF signal and a second input signal, and mixes its input signals to generate a mixed signal. The integrator/sampler receives the mixed signal and processes it to provide an output signal. The signal generator provides an operating signal in response to a selection signal. The operating signal has a frequency equal to the frequency of a reference signal, multiplied by a number. The second mixer mixes the operating signal with a template signal to generate the second input signal of the first mixer.