MICROWAVE SURVEY METER

• US 3,760,271 A
• Filed: 06/07/1971
• Issued: 09/18/1973
• Est. Priority Date: 06/07/1971
• Status: Expired due to Term

• Current Assignee: Leonard S. Smith, Reed E. Holaday, Stanley Monrad Jr. Bach
• Original Assignee: Leonard S. Smith, Reed E. Holaday, Stanley Monrad Jr. Bach
• Inventors: Smith, Leonard S., Bach, Stanley Monrad Jr., Holaday, Reed E.
• Primary Examiner(s): Rolinec, Rudolph V.
• Assistant Examiner(s): Karlsen, Ernest F.
• Application Number:
  US05/150,372
• Time in Patent Office: 834 Days
• Field of Search: 324/95,72.5,149 250/39 325/67,363 343/703
• US Class Current: 324/95
• CPC Class Codes: G01R 29/0814 Field measurements related to measuring influence on or from apparatus, components or humans EMC, EMI and similar testing in general G01R31/001, e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning

Abstract

A device to measure low level near field microwave power density, such as leakage from a microwave appliance. A radial array of semiconductor diodes functions both as an antenna and a detector. The dc current generated in the array by an electric field causes a voltage drop across a load resistance. The voltage drop is a function of electric field strength and is measured by a sensitive dc voltmeter calibrated in power density. A switching sequence in the device provides both an internal battery check and an operational test of the diode array before the device is utilized to measure a microwave field.

Claims

1. A microwave survey meter to measure low level near-field microwave power density comprising:

a radial array of semi-conductor diodes positioned in a single plane, each diode having first and second electrodes and having the first electrode of each diode connected directly to a common point, said radial array forming a microwave electric field strength detection probe wherein said radial array acts both as a detector and as an antenna, said detection being essentially independent of field polarization and said array causing a minimum perturbation to said field;

means connected to the first and second electrodes to convert the output signal from said radial array of diodes from a current function to a voltage function;

amplification and integration means responsive to the voltage function to amplify and integrate the voltage function; and

display means responsive to the output of the amplification and integration means to provide an indication of the magnitude of said signal in units related to microwave power density.

2. The microwave survey meter of claim 1 wherein the radial array of diodes is electrically forward biased so as to provide diode operation within square law.

3. The microwave survey meter of claim 2 wherein the means to convert said output signal from said radial array of diodes comprises application of the dc current output from said radial array of diodes across a load resistance, the resulting voltage drop being a function of the impinging electric field strength.

4. The microwave survey meter of claim 1 wherein there is also provided a function switch sequencing means wherein prior to operation of the meter for the measurement of microwave fields it is necessary to pass from an off position through a battery check position and a probe check position before arriving at an operation position, thereby providing an essentially automatic check of the meters'"'"''"'"' readiness for operation.

5. A microwave electric free field strength detection probe comprising:

an electrically forward biased radial array of semi-conductor diodes positioned in a single plane, each diode having first and second electrodes and having the first electrode of each diode connected directly to a common point;

a load resistor means electrically connected between the first electrode of said radial array of semi-conductor diodes and a junction;

microwave suppressing means connected between the second electrode of each diode and the junction to isolate the radial array of semi-conductor diodes from spurious RF signals picked up in a plane other than the plane of said radial array of semi-conductor diodes; and

ambient temperature compensation means electrically connected across the first and second electrodes of said diode array;

whereby a signal representative of microwave power may be obtained from across the load resistor means.

6. The microwave field detection probe of claim 5 wherein said microwave suppressing means are selected from the group consisting of resistors and wire elements surrounded by ferrite material and said ambient temperature combination.