Harris Corporation

Gerald W Collins

Hilmer I Swanson

A pulse step modulator comprising is disclosed including a plurality of series connected unit step modules, each including a DC voltage source and an associated actuatable switch for, when on, turning on the associated module to provide a unit step voltage. An output circuit is connected to the series connected modules for providing an output voltage to a load wherein the magnitude of the output voltage is equal to the sum of all the voltage sources of the modules that are turned on. A plurality of module turn on signals are provided, each for turning on a switch in one of the modules for the time duration of the turn on signal after which the switch is turned off. Each unit step module includes a transformer means exhibiting an associated unwanted capacitance between transformer means and circuit ground and which capacitance becomes charged when the associated switch is turned on. Each unit step module has capacitance discharge means for rapidly discharging the associated capacitance each time the associated switch is turned off.

Modulator having improved discharging unwanted capacitance

A zigzag antenna for broadcasting circularly polarized electromagnetic energy at a mean wavelength L. The zigzag antenna includes a zigzag shaped radiating element (10, 12) composed of plural essentially linear segments (20). These segments, each L/4 in length, are disposed end-to-end with each segment being at right angles to adjacent segments. L/2 non-radiating delay lines (22) are interposed between adjacent segments at alternate junctions between the segments, with the segments being directly joined at the remaining junctions. When fed with electromagnetic energy, the element will broadcast circularly polarized waves since each pair of adjacent segments are orthogonal in space and phase. In the described antenna embodiment, two radiators (10, 12) are arranged above a reflecting panel (16), and are fed from a central feed point (14).

Circularly polarized zigzag antenna

A slot antenna having particular application to the field of UHF broadcasting. The antenna is comprised of a rigid coaxial waveguide which is dimensioned so that electromagnetic energy propagates therethrough in the TE.sub.11 mode. Two longitudinal baffles are provided at diametrically opposing circumferential positions within the waveguide. These baffles stabilize the orientation of the mode (i.e., the mode polarization) within the waveguide so that it is known. Alternate methods of establishing a fixed mode polarization are also disclosed. Slots are provided along the exterior of the waveguide in appropriate circumferential positions relative to the mode polarization. Since the TE.sub.11 mode includes both longitudinal and transverse current components, vertical, horizontal, or circular polarization may be generated through the selection of appropriate positions, shape, and orientations for the radiating slots. In one illustrated embodiment, orthogonal slots are provided at selected locations along the exterior of the cylinder so that circular polarization is transmitted by the antenna. The antenna is preferably center-fed through use of a coaxial feed line which is run along the center of the antenna to a center feed point. Various methods for coupling the electromagnetic energy from the coaxial feed line to the TE.sub. 11 waveguide are disclosed.

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Quincy, IL, United States of America

Gerald W Collins