Abstract: An extendable half-wave dipole is capacitively coupled to a driven resonant helical antenna for use as on a hand-held, two-way portable radio, the helix being end fed. The dipole may be mounted adjacent to or collinear with the axis of the helix. The collinear mounting requires non-conductive portions on each end of the dipole. Optimum dimensional and performance characteristics are available without switching.

Abstract: An improved wideband phase modulator suitable as a simple modulation interface for existing phase modulated transmitters. The disclosed modulator arrangement utilizes a high stability reference oscillator and an associated phase locked loop for optimum long term stability. Means are included for extended phase range and high fidelity of modulation irrespective of loop bandwidth. Both tone and digital modulation is accommodated.

Abstract: A switching amplifier includes a pulse width modulator for converting a bipolar input signal, which may be a speech signal, into a train of unipolar pulses having durations which vary with the instantaneous absolute amplitude of the input signal. The pulses control the energizing of a series switch which supplies current to a switching bridge circuit. The switching arms of the bridge circuit are controlled by the polarity of the input signal. Another switch and several diodes are used to provide a path for output current when the series switch is open. The output current is filtered to remove fluctuations at the switching rate, and applied to a load. The amplified output voltage signal accurately follows the input signal, and the efficiency of conversion of DC power to AC output power can approach 100 percent, limited only by switching and filtering losses. A single polarity DC supply, such as a battery, is used to provide bipolar output current to an ungrounded load.

Abstract: A non-reciprocal signal path for RF over a broadband frequency range is provided by an isolator comprising two coils or meshes positioned at 90.degree. to each other adjacent at least one gyromagnetic or ferrite disc which is magnetically biased by a static magnetic field. Each coil is tuned by a parallel capacitor, each coil and capacitor having one end grounded to a surrounding electromagnetic shield. A resistive unilateralizing element is coupled between the input and output terminals and, being essentially non-reactive, provides the broadband characteristic. The energy from the reverse direction is dissipated externally in the resistive element. A magnetic return path of a high permeability material allows the use of smaller biasing magnets and reduces the effects of external magnetic fields.

Abstract: A digital detection system for binary differential phase shift keyed (DPSK) signals includes first and second multipliers to which the signal is applied, and which receive reference signals applied in quadrature to the two multipliers. The outputs of the multipliers are each applied through a filter to a one bit delay circuit, with the outputs of the filters and delay circuits being applied to third and fourth multipliers. The outputs of the third and fourth multipliers which receive signals from the two filters are summed to provide the detected digital signal. The filters may be matched filters each including an integrate, sample and dump circuit, and a data transition tracking loop coupled to the first multiplier and to the detector system output provides a bit synchronization signal for the matched filters. An I-Q loop may be coupled to the outputs of the two matched filters and controls an oscillator which provides the reference signals for the first and second multipliers.