Tester enables direct measurement of the resonant frequency of an yttrium iron garnet disk. The disk is tested while mounted on the isolator strip with less regard for dimensional flaws

Clauss, R. C.

English

NASA Technical Reports Server

Pa 
2 to 4GHz
Sweep
Generator
RF
Sweep
Directional f Frequency
Meter
July 1970	 Brief 70-10033 
.
	
NASA TECH BRIEF 
-4r 
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 Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
A Simple Tester Provides Resonant Frequency Measurements of Ferrite Devices 
VIG Disk 
Electro 
Magnet 
Horizontal
Drive
Oscilloscope 
Vertical 
Drive
The problem: 
The resonant frequency of a maser is determined by 
the shape of the isolator material, usually an yttrium 
iron garnet (YIG) disk, and the applied magnetic 
field. The thickness of the YIG disk is varied to ob-
tain the desired resonant frequency, e.g., to shift the 
maser frequency 300 MHz would require a 0.001-in. 
thickness change for a disk that has a 0.046-in, diam-
eter and is 0.0065-in, thick. A trial-and-error polishing 
operation for obtaining the final thickness is time con-
suming and impractical.
The solution: 
A simple tester has been designed and fabricated 
which enables the direct measurement of the resonant 
frequency of a YIG disk. The YIG disk can be tested 
while mounted on the isolator strip with less regard 
for dimensional flaws. The tester includes a combina-
tion clamp, temperature-controlled electromagnet, 
and a coupling line element for holding and coupling 
the signal to the disk under test; the coupling line also 
receives the reflected signal.
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics,and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19700000032 2020-03-16T23:59:30+00:00Z
How it's done: 
The figure shows a block diagram of the ferrite 
resonance tester. A microwave signal generator is 
swept over a particular range of frequencies, the 
signal being applied to a directional coupler through 
a frequency meter and pad. The frequency determin-
ing sweep-voltage is applied to the horizontal axis of 
the oscilloscope; the vertical axis of the oscilloscope 
receives the detector output voltage which is the recti-
fied, reflected microwave power coupled into the 
directional coupler from the line. The oscilloscope 
presentation appears as a straight horizontal line 
except for a sharp dip which occurs at the resonant 
frequency of the ferrite; the frequency at the minimal 
response point is measured with the frequency meter. 
The directional coupler transfers the microwave signal 
from the generator to the line and directs the reflected 
signal from the line to the detector. The magnet is 
adjusted electrically to provide the desired field 
strength; this presents an environment similar to that
which the YIG ferrite element encounters in a maser. 
The magnet, directional coupler, strip lines, and YIG 
disk are maintained at a constant temperature by a 
thermal control unit. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: B70-10033 
Patent status: 
No patent action is contemplated by NASA. 
Source: Robert C. Clauss of 
Caltech /J PL 
under contract to 
NASA Pasadena Office 
(NPO- 10678)
[1 
. 
Brief 70-10033 Category 01


A simple tester provides resonant frequency measurements of ferrite devices

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