Circuit with a sawtooth-modulated traveling-wave tube, which acts as a frequency converter and as an amplifier, simplifies microwave transmission. Lower power losses and reduced size and weight are also realized in this circuit

Allen, W. K.

Ippolito, L. J.

Nace, D. A.

English

NASA Technical Reports Server

	fo	 Band-Pass I fo 
Receiver	
-	 Filter 
40 )	 fo + f1
Sawtooth
Generator
Af 
I 
ravelir 
Wave 
Tube.,,
(fo +zf)=fi 
and
Band Pass

Filter
May 1965	 Brief 65-10127 
NASA TECH 
--	 __iI._	
-"-	 •i'i: 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Traveling-Wave Tube Circuit Simplifies Microwave Relay 
Transmitter 
fi Band-Pass
Filter
(f1) 
The problem: Long-distance microwave communi-
cation systems generally require signal amplification 
at active-repeater relay stations along the transmission 
path. To pievent feedback oscillations in the relay 
amplifier, the incoming microwave signal must be con-
verted to a different microwave frequency for trans-
mission. This conversion, usually accomplished by 
converting the incoming signal to an intermediate 
frequency which is then amplified and converted to 
a new microwave signal, has required a fairly complex 
system, consisting of a preselector, mixers, a local 
oscillator, amplifiers, and filters. 
The solution: A circuit employing a sawtooth-mod-
ulated traveling-wave tube, which serves both as a 
frequency converter and as an amplifier. 
How it's done: The microwave input signal at fre-
quency f0
 is coupled by an f0
 band-pass filter to the 
sawtooth-modulated (frequency M) traveling-wave 
tube, where transit-time modulation of the signal takes 
place. When the slope of the sawtooth modulating 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern. 
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
signal is positive, the output from the traveling-wave 
tube comprises signals of frequency f 1
 (equal to f0 + 
!M) and f2
 (equal to f 1 + sf), respectively. These 
signals are coupled to two band-pass filters tuned to 
frequency f 1
 and f2, respectively. The output from the 
f 1
 band-pass filter is coupled back to the input of the 
traveling-wave tube. The output from the f 2
 band-pass 
filter is then a twice-amplified microwave signal at 
frequency f2, which is transmitted by the system. 
Notes: 
Lower power losses and reduced size and weight 
are realized in this circuit, because it eliminates 
separate rf mixers and uses fewer filters than re-
quired in previous designs. 
Inquiries concerning this invention may be directed 
to:
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland, 20771 
Reference: B65-10127
(continued overleaf) 
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19650000126 2020-03-11T17:22:51+00:00Z
Patent status: NASA encourages the immediate 
commercial use of this invention. It is owned by 
NASA, and a patent application has been tiled. 
Royalty-free nonexclusive licenses for its commercial 
use are available. Inquiries concerning license rights 
should be made to NASA, Code AGP, Washington, 
D.C., 20546. 
Source: W. K. Allen, L. J. Ippolito and D. A. Nace 
(GSFC-299) 
Brief 65-10127	 Category No. 01


Traveling-wave tube circuit simplifies microwave relay

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server