TRIP REPORT - (SANITIZED)

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03424A002000080023-8
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 5
• Document Creation Date: December 22, 2016
• Document Release Date: September 20, 2011
• Sequence Number: 23
• Publication Date: June 26, 1959
• Content Type: MEMO

Sanitized Copy Approved for Release 2011/09/20: CIA-RDP78-03424AO02000080023-8
TIAL
Office Memorandum ? UNITED STATES GOVERNMENT
:The Files - Contract 605
suBJEcT:Trip Report -
1. On 23 June 1959
on Contract 605, Task Orders 1, 2, ,
and 8.
DATE: 26 June 1959
E/R+D-EP visited
to monitor progress
2. High Gain Inflatable Pouchable Antennas, Task 1 - One of these
antennas has been received at Headquarters and was f d to be mechani-
cally acceptable. A study of the test data at~ showed that the
antenna met our specifications adequately. Gain of 6 foot inflatable
dish antenna varies from about 16 db at 350 mcs to 35 db at 6,000 mcs,
while the 2 foot dish antenna showed gains from about 25 db at 6,000
mcs to about 37 db at 10,000 mcs. VSWR for the 62 foot dish antenna
gernerally stayed below 3:1 with only three 'pop-ups' in the entire
range, each one being very narrow and not exceeding 3.6:1 when com-
pensated for line loss. The 2 foot dish antenna showed VSWR below
2:1 over the range of 6,000 to 10,000 mcs even with the single electro-
magnetic horn feed. Verbal acceptance of the other air inflatable
antennas was made. Q delivery schedule now calls for delivery
of six air inflatable antennas instead of the original five antennas
called for in the contract. The first antenna was to serve as an
expendable prototype, but sin t has been found acceptable, all six
antennas will be delivered. ill request an overrun for this
project, the overrun not being due to the construction of six antennas.
experienced considerable difficulty in constructing the original
antenna and used considerable more engineering and model ship time than
their original proposal indicated they would. The amount of the overrun
will be about $8,000 to 10,000 according to . Past experi-
ence has shown that the amount of the overrun will -r-hably be con-
siderably more than that quoted verbally by the a engineers.
3. CS-8/AN-20 Antenna - Task 2 - Electrical test data for this
antenna, originally designed to cover the range of 30 to 600 mcs,
shows that the antenna is almost omnidirectional in the range of 30
to 55 mcs. At 30 mcs the VSWR is 3:1. Above this frequency the VSWR
rises rapidly to 17:1 at 47 mcs and then tapers off to the nominal
value of 3:1 at a frequency of about 52 mcs. The instruction book for
this antenna is in publication at the present time and we have been
assured that it will be deliverable not later than the first of July.
Upon delivery of the instruction book for this antenna Task 2 can be
terminated.
COI? I-I LI\ 11 IAL
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co a~1 e k.~'k ~d oll
4. Parabolic Reflector and Feeds - Task 4 - One of these antennas
has been delivered to Headquarters and has be 7found acceptable mechanic-
ally. Examination of the test data at showed gains from about
16 db at 600 mcs to 35 db at 6,000 mcs wi a SWR of less than 3:1
over the entire range. Verbal acceptance of the other four antennas
was made with delivery expected within 60 days. 0 has requested
that acceptance of these antennas be put in writing for their records.
5. 30-1,000 me Log Periodic Antenna - Task 6 - has signed
the contract for the construction of five of these antennas and has
started some model work. A new concept will be used in the construction
of this antenna. Basically the new structure will resemble an array of
dipoles with their spacing and lengths varied in a logarithmically
periodic manner. The feed will consist of a two wire transmission line
which criss-crosses between alternate elements so as to provide the
necessary phase reversals between adjacent elements. This new design
promises to be considerably lighter than conventional log periodic
structures and yet it will maintain the high gain and constant beam-
width of the other types of log periodic structures,
relaxed our specifications as to detector sensitivity somewhat, using
the original specification figures as a design goal. stated
that in addition to the test equipment which is to be supplied as GFE
for this task he would also like the loan of two or more video amplifiers
of the type which will be used with this system. He will accept the
VA-7 as a representative video amplifier. Although he stated that they
will not need the test equipment for several months, he was told that,
because the equipment was being held for pr t shipment of
the equipment would make our job considerably easier. agreed
to accept the test equipment within the next two months and keep it
in storage until it is actually needed.
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8. Near VialA ation of Radiated Fields - A discussion
was held with to discuss the possibility of reducing or
eliminating the near field of an antenna system so as to provide
signal security against the close-in intercept operater. The follow-
ing equations are general forms for the radiation field of a small
dipole antenna and holds quite well for all types of arrays, being
modified by only a multiplier in the case of a directive array.
Eo _ 2d,1 w si;7&1k-7v _t-% ,_w(__r
r V w
Er = 2 C0 Ce- 9 V(* ) -r~.~; t W ( t -
4,j r,3
As can be seen from the above equation, all the terms are inter-
dependent with a and r as common factors. Reduction of the terms
which vary as r-- 2. and r 3 necessitate the reduction of the
term which varies as r--'and which produces the far field. Maxwells
four basic equations for an electromagnetic field are as follows:
V XH D" 7)(E
s) p? D-p) 4? =a
If a ring of silence is generated about an antenna system, it can
be shown from the four above equations that if the Poynting vector
is zero at the ring of silence, it must be zero at all points beyond
the ring. Thus cancellation by phase reversal of a second near field
is not possible. One possible approach however is to space two
antennas of identical characteristics equidistantly and considerably
removed from the operator. Theoretically the field directly above
and very near the operator will be zero. Although this will not
produce security for the system, it might protect the operator.
A second approach is to move the frequency of operation to the VHF
region so that parabolic antenna systems might be used. There are
methods of almost completely cancelling side lobes by using absorb-
ing material around the edge of the parabola and radiation would be
in only one direction. This system, when using highly redundant
transmissions for tropo-scatter communications, would provide security
in beamwidth and should be almost undetectable at low angles. A
third possible approach is to place the normal transmitting antenna
above ground and a second below ground. The wave radiating from
the above ground antenna can be roughly represented by the following
expression:
The wave propagating through the ground would roughly obey the follow-
ing equation:
If the below ground wave is delayed in time an amount equal to?degrees,
as~nstr~st s w Wen tPMjt4,ou;Aeso'ief i; * 'E .o
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CONHO
the other through the earth, a relative phase rotation will result
due to the slower velocity of propagation for the below ground wave.
At some point removed from either antennas, the waves would be in
phase and it is possible that they would radiate from this area of
intersection. There is unfortunately no experimental evidence for
this last possibly to test its feasibility.
9. New Type of SHF Antenna: Equiangular Spiral - On page 181
of IRE Transactions, Antennas and Propagation, Volume AP-7, No. 2,
John Dyson of the University of Illinois describes a new type of
antenna called the equiangular s iral antenna, which will operate
satisfactorily to 10,000 mcs. was questioned about
the operation of this type of antenna. Gain obtainable with this
antenna approximates dipole gain, the pattern is bidirectional,
and the polarization is circular. indicated that they
would be interested in constructing some of these antennas if we
F-- I
rresented it to them in the form of a requirement.
was told that if a requirement for such an antenna arose, we would
F- I
talk to him more about it. It is understood that
is now selling such an antenna commercially. It differs in that
the slot structure is two dimentional and is backed up with a cavity
containing annular rings perpendicular to the x, y plane of the
spiral. These rings provide roughly the same effect as the varying
slot depth in antenna.
Distribution:
R+D Subject File
Monthly Report
R+D Lab
SPS
605, T.O. 2
605, T.O. 1
605, T. o. 4+
EP Chrono
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 Sanitized Copy Approved for Release 2011/09/20: CIA-RDP78-03424AO02000080023-8
Sanitized Copy Approved for Release 2011/09/20: CIA-RDP78-03424AO02000080023-8