antennas just the best thing ever? Okay, maybe not -- but in
communications systems they are the differnce between copy and no copy,
the difference between signal and noise, and all those measures of
success. Perhaps, I am biased a little, having worked in the
antenna field for so many years. Anyway, this page shows some
photos of antennas I have built outside of the work place; they are
mostly ham radio-related designs that are easily recognized.
40 Meter Magnetic Loop Antenna (almost)
my attempt at a magnetic loop antenna made from parts found in the
garage. The tuning capacitor has a range from 25 pF to 250 pF,
the half inch copper pipe is about 29 inches. I made the coupling
loop about 6.5 inches in diameter. Tuning is achieved from 7.20
MHz to 22.3 MHz.
$20 HF Mobile Antenna
This was a fun little project for a multi-band HF antenna. The construction design is from this April 2000 QST article.
This antenna could be tuned from 20 m through 6 m with no problem
using a 40 inch whip -- other than the inherent need to move the tapped
coil connection, of course.
2.4 GHz Co-Linear Dipole Corner Reflector (Wi-Fi)
traveling I have often needed a directional antenna to connect to
remote Wi-Fi networks; this was the motivation for this antenna.
I made a traditional co-linear array, using available brass tube
stock in the garage, scrap connector, a PVC enclosure, gutter screen
for the corner reflector, and a foam block to space and center the
dipole array. The assembly is ealily collapsed for transit when
not in use. The gain of the antenna is probably about 13 dBi to
15 dBi, the latter being the theoretical maximum.
40 Meter Field Antenna
is just a wire antenna, sort of like the W3EDP field-deployable antenna
-- but shorter; the long and short wires are 67 ft and 17 ft,
respectively. The dimensions were give to me by my firend, Walt.
The wires are terminated with bananna plugs and these plug
directly into a UHF center conductor, as we know. The antenna is
used with a tuner. My contribution to this is making the wind-up
spool mechanisim out of New Mexico Green Chile container lids!
Holding the large knob, you can wind the antenna up similar as on
a fishing reel. Here are the photos.
And, of course, we want all our antennas to be HOT!
Multi-band HF Antenna
antenna is the Broadside Doublet described by L. B. Cebik, W4RNL
(SK) in his document, "My Top Five Backyard Multi-Band Wire HF
Antennas." At 88 feet in length, and with a tuner, the antenna is
usable from 80 meters through 20 meters -- and it fits within the
boundaries at my QTH. I used Wireman's Type 504 16 AWG copperclad
wire, made my own center insulator out of plastic cutting boards
from Harbor Freight, and made end insulators from scrap Corian
Tape Yagi-Uda Antennas for 2 meter and 70 cm Satellite Operation
antennas were designed to be light weight and transportable for use on
my CNCTRK positioning system. Each of the designs were optimized
for Gain, F/B, and Return Loss in the satellite bands. I believe
the antennas MAY hold the record for the highest Gain/Pound ratio
[dBi/lb} (who ever heard of that specification?). Anyway, using
the Panduit cable raceway enables all the antenna elementsto be removed
from the boom for transportation and quickly snapped in place for
operation. I use a pair of these in a crossed
configuration. Here are some photographs and all the NEC design files from 4nec2.
I hope that any improvements folks make to the designs will be made
available to the community. These antennas, along with some
commercial designs, were measured on the antenna measurement range at
the 2017 SVHFS Conference in Charlotte; a write-up on the results are in our NFARL Club eNews from May 2017. Notes on the construction details and materials used in the design are contained in the file: Tape_Yagi--Take_Two.pdf. Spreadsheets in Open Office and Excel
format contain the element lengths and locations used for each of the
two designs. Have fun with the antenna and feel free to contact
me with questions (and improvements).
More antennas to come . . .