PROGRESS REPORT FOR MONTH OF NOVEMBER 1958

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03424A002100010007-2
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 2
• Document Creation Date: December 22, 2016
• Document Release Date: July 10, 2012
• Sequence Number: 7
• Publication Date: November 1, 1958
• Content Type: REPORT

Declassified in Part - Sanitized Copy Approved for Release 2012/07/10: CIA-RDP78-03424AO02100010007-2
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REASON
Purpose:
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PROGRESS REPORT
FOR
,MONTH OF NOVEMBER 1958
BROADBAND ANTENNAS, FILTERS AND DET T kts'
To determine the feasibility of developing a broadband system
for the 50 me to 140,000 me frequency range.
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Personnel: Electrical Engineers
Status: The low frequency cut off characteristics of the printed logarith.
mically periodic antenna of 0 Y angle for the 500 to 10,000 me
frequency range have been evaluated. Defining the cut off frequency
as that frequency at which the response is 3 db down then at .85 of
this cut off frequency the response is 9.5 db down. Our data indi-
cated, however, that this fall off was not monitonic. The oscillations
in the response curve in this region were caused by the change of
impedance of the antenna below the cut off range and the position of
the crystal holder which was separated from the antenna feed point by
a length of coaxial line. The effect of the dielectric on this
antenna has been reduced to what is considered a satisfactory amount
by reducing the dielectric constant of the board the antenna is
printed on and by choosing a thinner board. Detailed pattern data
on this antenna will be included in the final engineering report.
The response characteristics of the antenna to be used in the
50 to 500 me range have been evaluated. It was found that the response
of the antenna was degraded considerably in certain frequency ranges
when the antenna was in close proximity to a person. It is felt,
however, that this difficulty can be overcome to some extent in the
development phase of this program by optimizing antenna parameters
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Declassified in Part - Sanitized Copy Approved for Release 2012/07/10: CIA-RDP78-03424AO02100010007-2
 Declassified in Part - Sanitized Copy Approved for Release 2012/07/10: CIA-RDP78-03424AO02100010007-2
is
with this aim in mind. The response of this antenna was compared
to that of a matched half wavelength dipole at 3 frequencies in
the frequency range of the antenna. The comparison was favorable
within the measuring accuracy and the assumptions that were necessary
in the measurement and calculation of the response.
Future Plans: It has now been determined by the customer that the cut off
characteristics of the antennas themselves will not be adequate.
Therefore, the future effort will be devoted to investigating
closely the size requirements for printed circuit band pass type
filters. We will try to determine during the first two weeks of
December whether it is necessary to devote a large amount of
additional time to this filter feasibility effort.
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Declassified in Part - Sanitized Copy Approved for Release 2012/07/10: CIA-RDP78-03424AO02100010007-2