Antennas

Aren't 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)
Here's 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.

loop1 photo    loop2 photo    loop3 photo


$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.

loading coil photo        base coil photo


2.4 GHz Co-Linear Dipole Corner Reflector (Wi-Fi)
When 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.

colinear photo    corner photo    transit photo


40 Meter Field Antenna
This 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.
chile1 photo        chile2 photo
And, of course, we want all our antennas to be HOT!

Multi-band HF Antenna
This 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 material.  

doublet photo


Tape Yagi-Uda Antennas for 2 meter and 70 cm Satellite Operation
These 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).

antennas photo70 cm antenna2m antenna




More antennas to come . . .


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