Slow-wave structure of traveling-wave maser utilizes comb system which is comprised of ruby on one side and alumina on other; alumina also supports isolator material. Radiation at pump frequency is coupled to ruby through shaped alumina strips. Contact between ruby bars and comb completes conductance path for heat transfer

Clauss, R. C.

Quinn, R. B.

English

NASA Technical Reports Server

July 1973
	 B73-10293 
•	 NASA TECH BRIEF 
NASA Pasadena Office
	 -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 National Technical Information 
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be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
_- - 
Improved Masers for X-Band and Ku Band 
The problem: 
To provide high-gain, low-noise amplifiers having 
wide tuning ranges at frequencies above 7 GHz. 
The solution: 
Traveling-wave masers which use multiple-fre-
quency pumping and have ruby crystals oriented 
0=900. 
How it's done: 
The slow-wave structure of the traveling-wave 
maser utilizes a comb system which is comprised of 
ruby on one side and alumina on the other; the alu-
mina also supports the isolator material. Radiation at 
pump frequency is coupled to the ruby through 
shaped alumina strips. 
The ruby bars are fabricated from "zero degree" 
Czochralski ruby (0.05 to 0.07% chromium oxide) and 
C-axis orientation is along the length of the comb; 
the ruby bars are forced against a copper comb by 
pressure from beryllium-copper springs located be-
tween the ruby bars and the center divider of the 
traveling-wave maser structure. The beryllium-cop-
per springs also serve to hold the isolators in place. 
Contact between the ruby bars and the comb com-
pletes a conductance path for heat transfer from the 
ruby bars through the copper mass constituting the 
body of the traveling-wave maser to a flange which 
supports the entire maser; the flange is in direct con-
tact with a 440 K refrigerator of the type commonly 
used in S-band maser systems. The isolator consists 
of an alumina bar to which are glued yttrium-iron 
garnet (YIC) strips. The YIG strips are located in 
regions of circular polarization near the base of the 
comb structure.
The 90° C-axis orientation of the ruby (with respect 
to the magnetic field direction) determines the mag-
netic field and pump frequency requirements; accord-
ingly, at X-band, a 0.5-tesla (5,000-gauss) magnetic 
field (uniform within ±0.0002 tesla) is provided by a 
superconducting magnet and the actual field across 
the active region of the maser is varied electrically 
from 0.48 to 0.52 tesla (4,600-5,200 gauss). A 0.7- to 
0.8-tesla (7,000-8,000-gauss) magnetic field is used 
for the Ku-band maser. 
Ruby crystal misorientations of the order of ±1° 
can be tolerated at 0=90° without degradation of 
performance; as a result, orientation and assembly 
procedures need not be as closely controlled as with 
the usual 54.7-degree ruby orientation, which is 10 
times more sensitive to deviations; moreover, crystal 
quality requirements are readily met by state-of-the-
art crystal growing procedures. Efficient operation of 
the maser is obtained by pumping with a push-push 
technique; the push-push pump method with two 
separate pump sources as used in this development 
provides larger transition probabilities and higher 
measured inversion ratios than the push-pull method. 
X-band traveling-wave maser performance has 
been measured over the maser's tunable range (7,750 
—8,750 MHz). Net gain of 45 dB is available at any 
frequency in this range; the instantaneous bandwidth 
at 45-dB net gain is 17 MHz. A bandwidth of 50 MHz 
is achieved by reducing maser gain to 25 dB through 
the use of magnetic field-shaping coils. The equiv-
alent input noise temperature of the maser is 6.5°K 
at 8,415 MHz and 8.5° K at 7,850 MHz. 
Ku-band maser performance has been measured 
between 14,300 and 16,300 MHz. More than 30-dB 
(continued overleaf) 
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net gain is obtainable at any frequency in this tuning 
range; for example, at 15,300 MHz, the net gain was 
found to be 47 dB with a 17-MHz instantaneous 3-dB 
bandwidth and an equivalent input noise temperature 
of 8.5°K. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP 73-10293
Patent status: 
This invention has been patented by NASA (U.S. 
Patent No. 3,676,787). Inquiries concerning nonex-
elusive or exclusive license for its commercial devel-
opment should be addressed to: 
NASA Patent Counsel 
Mail Code 1 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Source: Robert C. Clauss and Rex B. Quinn of

Caltech/jPL
under contract to
NASA Pasadena Office
(NPO-11437)
. 
. 
B78-10293	 Category 02


Improved masers for X-band and Ku band

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