John J Keim

US Patent:

51573385, Oct 20, 1992

Filed:

Jan 22, 1991

Appl. No.:

7/643785

Inventors:

James M. Motherbaugh - Akron OH
John E. Keim - Lodi OH

International Classification:

G01R 2706

US Classification:

324637

Abstract:

The invention described a pocket size antenna VSWR indicator having a self-contained low level wideband RF signal source which is applied to an antenna under test through a four arm RF resistive bridge circuit. The bridge circuit has been designed to be very accurate and reliable and provides a novelly positioned reference against which the reflection co-efficient of the transmission system is compared to reliably indicate the VSWR of the system. The bridge circuit provides a flat response over the desired wideband frequency range and over the range of antenna impedances which may be encountered. The RF null or bridge balance is detected in a radio receiver or transceiver tuned to the desired operating frequency, from which an indication of antenna VSWR may be provided. The antenna VSWR may be indicated in a variety of way, such as by means of a numbered or colored dial, a plurality of LEDs or an audio tone shift against an internal reference. Alternatively, the indicator may be calibrated to read VSWR directly by number or by means of a color-dial indicating good, poor or non-usable VSWRs.

US Patent:

51855682, Feb 9, 1993

Filed:

Jan 22, 1991

Appl. No.:

7/643832

Inventors:

James M. Mothersbaugh - Akron OH
John E. Keim - Lodi OH

Assignee:

Circle Prime Mfg. Co. - Cuyahoga Falls OH

International Classification:

G01R 2106
H01C 108
H03C 162

US Classification:

324 95

Abstract:

The invention describes an internal test load and method for forming an internal test load which is adapted to absorb energy from a power source such as an RF transmitter, transceiver, or amplifier. The test load is positioned internally within a housing, and includes at least one impedance device, such as a power resistor, coupled to the power source which is matched to the impedance thereof. The impedance device is supported on a heat sink which is adapted to absorb heat generated by the impedance device so as to be distributed over a relatively large area constituting the heat sink. The heat sink is positioned in spaced part relation to the housing, and is not directly supported or secured to the housing. A potting material surrounds the load assembly and supports the heat sink, wherein the heat sink effectively "floats" within the potting material such that heat absorbed by the heat sink will not be directly transferred to the housing, but will be dissipated through the potting compound. As an example, the internal test load is applied to an RF watt meter for testing low power RF transmitters, transceivers and RF amplifiers without an external load or antenna connected separately thereto.