Inexpensive lightweight unit is easily carried in coat pocket or attached to belt, detector sounds alarm in presence of dangerous microwave radiation levels. Unit consists of antenna, detector, level sensor, keyed oscillator, and speaker. Antenna may be single equiangular spiral or set of orthogonal slot dipoles. Signal detector is simple diode in small package

Kolbly, R. B.

English

NASA Technical Reports Server

August 1974	 B74-10097 
NASA TECH BRIEF 
S	 NASA Pasadena Office 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Pocket-Size Microwave Radiation Hazard Detector 
The problem: 
Microwave radiation can cause serious internal burns 
in people working in the vicinity of high-power trans-
mission equipment. At this time, hand-carried micro-
wave monitors are available, but few people use them 
because of the inconvenience of hand carrying and 
because they have to be checked visually to detect the 
danger. These monitors are expensive and require 
calibration every time they are used. 
The solution: 
An inexpensive lightweight unit has been developed 
for the detection of microwave radiation. Easily carried 
in a coat pocket or attached to a belt, the detector 
sounds an alarm in the presence of dangerous micro-
wave radiation levels.
How it's done: 
The unit consists of an antenna, a detector, a level 
sensor, a keyed oscillator, and a speaker. The antenna 
may be a single equiangular spiral or a set of orthogonal 
slot dipoles. The signal detector is a simple diode in a 
small package. 
As shown in the circuit diagram, the level sensor is a 
standard integrated circuit, such as a pA7 1 OC differential 
comparator or its equivalent. A small potentiometer R1 
sets the trip level or sensitivity. R2
 is a potentiometer 
which sets the level at which the equivalent microwave 
input, developed at point 2 of pushbutton switch Si, 
would represent a safety hazard. When switch S 1
 is 
pushed to position I, an output sound is obtained which 
indicates that the battery and the electronics system 
are operational. Switch S 1
 is normally in position 2, 
except during the operational test check. 
Test Adjust
Test Pushbutton 
Test
/ 
/ 
>-Hmh —100 MV Sensor Multivibrator	 '1kHz Speaker 100 mA 
-	 R1	 (Class B) 
Sensitivity
Microwave Detector 
. (continued overleaf) 
This document was prepared under the sponsorship of the National
	
Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	
information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19740000097 2020-03-17T14:05:03+00:00Z
The gated astable multivibrator (keyed oscillator) is 
a dual-gate (such as a ,.LL9 15 or its equivalent) integrated 
circuit which is wired as an astable multivibrator to 
furnish the warning tone. The multivibrator is gated on 
by the output of the level sensor. The tone output is 
amplified and drives a small speaker. 
Notes: 
1. The microwave detector may be of interest to 
microwave equipment manufacturers and to people 
working on microwave antenna installations. 
2. Requests for further information may be directed to: 
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: B74-10097
Patent status: 
Title to this invention, covered by U.S. Patent 
No. 3,753,116 has been waived under the provisions 
of the National Aeronautics and Space Act [42 U.S.C. 
2457(0], to the California Institute of Technology, 
Pasadena, California 91109.
Source: Richard B. Kolbly of
Caltech/JPL
NASA Pasadena Office

(NPO-1146 1) 
B74-10097	 Category 02,03


Pocket-size microwave radiation hazard detector

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server