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1994-04-02
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3KB
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69 lines
SUBJECT: Tape Antennas
Thanks goes to Jim Grubs for the idea.
Tape antennas seem to be an interesting way for apartment dwellers,
travelers, and others who need a quick antenna that can be used locally.
For these experiments I used copper tape, 1/2-in wide for my tests.
The following antenna types were tested:
o J-Pole
o Half-wave Dipole
o Full-wave Loop
Tape antennas are not new. I haven't seen much about tape antennas
with the exception of SAREX, used aboard the Shuttle. Even this antenna
was quasi-tape-type.
In general, the tape antennas had some interesting propagation
results due to the location of testing. Locally, the antenna is excellent.
Within a mile or two, the antenna works as well as an outside antenna. But,
due to the single floor building I work in these results may be better
if the antenna was located on a higher floor.
Propagation outside the local area was a function of which way the
window faces. Generally, the antenna pattern was not omni, but rather an
attenuated omni pattern to the side where the building faces.
Figure 1: Signal levels in dBm.
-21 -20 -17 1 12 16 18
-21 21
------------
| |
-22 | | 23
| |X
| | 24
| |
| | 22
-21 ------------
19
-22 -19 -16 2 11 17
These were the results of the Half-wave Dipole. Input level was
30dBm, CW, at 145 MHz. I hope FIDO didn't screw up the picture. The
distance from the building was taken at 100 feet using an EMC testing
dipole and an HP-8562 spectrum analyzer. Coax was a 72" section of
Adams-Russell 1999-0072 with precision 'N' connectors.
All readings were taken at ground level (standing there normally).
The transmitter was placed in a window at 4-ft off the ground at the feed.
Further results will be posted after I finish testing a few other
designs.
-WS