Amplifier Research Corporation

Donald R Shepherd

Frank A Bohar

Frederick Schirk

Frequency-dependent phase center movement in near-field, unshielded, electromagnetic susceptibility testing using a log-periodic dipole can be significantly reduced by bending the rearmost dipole elements forward. Each bent dipole element has an inner portion and an outer portion connected to each other at a bend, the inner portion extending outward from a boom in substantially perpendicular relation to the boom, and the outer portion extending obliquely outward and forward from the bend. The frequency range of the antenna can be extended by forming each element of the longest dipole with an undulating shape when viewed in a direction along the boom.

Electromagnetic susceptibility testing apparatus

A directional coupler for r.f. power measurement utilizes a capacitive voltage divider connected to the center conductor of a length of transmission line. The output of the divider is connected to the input of a field effect transistor amplifier, which makes the divider essentially frequency independent over a wide frequency range. The outer conductor of the transmission line comprises two sections separated by a gap and connected to each other by an annular resistor permitting a current sample to be tapped. The annular resistor is disposed between two parallel circuit boards disposed in radial planes. Circuit components, including the field effect transistor amplifier are mounted on one of the boards. The output of the amplifier and the current sample are combined algebraically at a junction to provide a signal representing forward or reflected power in the transmission line.

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Landsale, PA, United States of America

Donald R Shepherd