Compact back-to-back trapezoidal tooth log-periodic /TTLP/ antenna with frequency-independent characteristics is formed by reducing the angle between the two elements of a basic TTLP to zero. The back-to-back antenna, arranged in various configurations, provides monopulse operations in one or two planes and in various polarizations

Schumacher, C. N.

English

NASA Technical Reports Server

February 1966	 Brief 66-10066 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Antenna Configurations Provide Polarization Diversity 
The problem: 
The basic trapezoidal tooth log-periodic (TTLP) 
antenna operates in only one plane and one polariza-
tion. Arranging more elements in various configura-
tions to provide dual-plane and multipolarization 
operation is impractical because of the size of the 
resulting structure and the interaction that would 
occur between the various elements. 
The solution: 
The angle between the two elements of a basic 
TTLP is reduced to zero to form a compact back-to-
back antenna with frequency-independent character-
istics. The back-to-back antenna can be arranged in 
various configurations to provide monopulse opera-
tion in one or two planes and in various polarizations.
How it's done: 
A single coaxial cable, shielded by the support 
boom of one of the elements, is used to feed both 
elements of the back-to-back TTLP as seen at upper 
right. Arranging two of the back-to-back TTLP's and 
feeding each independently results in an array of back-
to-back TTLP's as seen at lower left. Exciting the ele-
ments in and out of phase results in frequency inde-
pendent monopulse operation in one plane and one 
polarization. Excitation is through hybrids and as-
sociated microwave equipment. Extending the struc-
ture still further by adding two more elements to form 
a pyramid would result in monopulse operation in two 
planes. Dual polarization operation is accomplished 
by employing two of the back-to-back TTLP's and 
(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.
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meshing them orthogonally along the same axis as 
shown at lower right. The elements may be fed inde-
pendently or together and by varying the phase or the 
current, circular and rotating linear polarizations can 
be obtained. 
Notes: 
1.Use of four of the elements, shown at lower right, 
arranged in a four-sided pyramid, permits monopulse 
operation in two orthogonal linear polarizations and 
right or left circular polarization. 
2. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland, 20771 
Reference: B66-10066
Patent status: 
No patent action is contemplated by NASA. 
Source: Charles W. Schumacher 
of Airborne Instruments Laboratory, 
Division of Cutler Hammer 
under contract to 
Goddard Space Flight Center 
(GSFC-74)
. 
Si 
Brief 66-10066	 Category 01


Antenna configurations provide polarization diversity

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