Dosimeter determines time-integrated radiation dosage to which an individual is exposed. Integration is measured chemically in proportion to radiation detected. Wearer receives an exposure measurement representing an average of the dose over the entire body

Bartlett, R. G.

Bird, F.

English

NASA Technical Reports Server

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April 1971	 Brief 71-10075 
NASA TECH BRIEF  
NASA Headquarters 
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.F. 20546. 
Microwave Dosimeter: A Concept 
The problem: 
To design a device that will detect and measure 
the time-integrated radiation dosage to which an 
individual is exposed. The device should be so de-
signed that the wearer would receive an exposure 
measurement representing an average of the dose 
over the entire body. 
The solution: 
A microwave dosimeter for determining time-
integrated radiation dosage. Variation in a dc 
electric current produces a shift in the pH of an 
acid solution, causing a color change in an in-
dicator cell. The integration is measured chemically 
in proportion to radiation detected by microwave 
electronics components. 
How it's done: 
The proposed microwave dosimeter would be 
similar in performance to the well-known pocket-
carried nuclear radiation gage. The device (Figure 1) 
consists of an omnidirectional antenna unit, an elec-
tronics module, an integrator detector, and a battery 
for the electronics. 
The antenna is designed to capture sufficient 
radiation energy to drive the electronics signal 
conditioner. A dipole antenna (short relative to the 
radiation wavelength) has a toroidal-shaped power 
pattern, where the dipole axis is normal to the 
equatorial plane of the toroid. Four dipoles, 
arranged as shown in Figure 2, provide an omni-
In the electronics module, energy intercepted 
by the antenna is fed through a diplexer to a full-
wave rectifier. A signal conditioning section suffi-
ciently amplifies the rectified signal to operate-the 
integrator detector.
-. Leads 
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Omnidirectional 
Circularly 
Polarized 
Antenna 
Battery1	
End Cap 
Figure 1. Microwave Dosimeter 
directional pattern for circularly polarized radiation. The integrator detector takes into consideration 
Since the radiation wavelengths to be detected the duration of exposure as well as the radiation 
are in the 1-to-10 centimeter range, the dipole an- flux density. Figure 3 is a schematic showing the 
tennas which are short in comparison to those wave- dye marker chemical integrator which gives a visual 
lengths will be physically unobrusive and con- indication of radiation dosage by a color change in 
veniently packaged. 	 the indicator under the viewing window. As radia-
(continued overlear) 
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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=19710000074 2020-03-17T02:22:32+00:00Z
Heat Seal 
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Electrode 
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Top Elect 
(Screen)
Heat Sthd
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tion impinges on the indicator, the change in the 
dc current produces a change in the pH of the acid 
solution with which the indicator pad is saturated. 
This change is linearly reflected in an indicator pad 
Indicator 
Pad 
_RL 
Dipole Schematic	 Dipole Arrangement	 Heat Seal
Figure 2. Dipole Schematic and Arrangement 
color change, which is proportional to the product 
of current and time during exposure. 
Notes: 
1. This development is in conceptual stage only, 
and, as of the date of publication of this 
Tech Brief, neither a model nor prototype has 
been constructed.
Figure 3. Chemical Current Detector- Integrator 
2. No further documentation is available. 
Patent status: 
No patent action is contemplated by NASA. 
Source: Frederick Bird and Robert Bartlett of

Allied Research Associates, Inc.

under contract to

NASA Headquarters
(HQN- 10407) 
Brief 71-10075	 Category 01 
*14


Microwave dosimeter - A concept

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