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The N3UJJ/N3UKI Antenna Project
Prototype Number One is done
What you see above is prototype #1 of the N3UJJ/N3UKI Parallel-Cage Dipole
note.. above picture (and link are 5 pictures merged together)
for a Hi-Rez (35 meg) image click here
The goal of the "Antenna Project" is to come up with an efficient Multi Band Horizontal antenna.
By efficient we mean an antenna that will radiate 90% or more of the energy output from the transmitter/amplifier, without a tuner and without using ladder/window line.
The problem with multiband HF antennas and coax is LOSS, the only way we can the full bandwidth on each band with a low swr is with a cage dipole, so the plan is to see if we can get a 4 cage dipole built in a fan or parallel configuration. One big consideration is weight, 4 cage dipoles for 40/30/20/10 uses almost 1,000 feet of wire. That alone is going to make for a heavy antenna, what's going to happen in a ice storm or sleet?
We (N3UJJ & N3UKI) have success" with prototype #1 and are now fine tuning the construction.
Prototype # 1 is a "Dual Band" (40 -20 Meter) Parallel Dipole Antenna, each Dipole is a "Cage Dipole"
SWR on each band is BELOW 1.5, for the FULL BAND
This means basically that we are radiating 95% of the energy that it is feed with.
And no antenna tuner is needed!
Prototype #2 is planned to be a "4 Band" ( 40 - 30 - 20 - 10) antenna and should go up the weekend of February 7th 2009 if weather permits, the cages are built, but assembly must be done outside
As soon as we work out a few construction issues, full plans and pictures will be posted here.
At this time we have no plans to sell this antenna, we plan on posting construction plans.
This antenna takes less then a day to build, and the current costs (excluding mistakes)
is less than $125.00, and we can't tell you how good it feels to build your own antenna.
Prototype #1 is constructed of the following:
8 one inch pvc couplers (20 meter spacers)
16 two inch pvc couplers (40 meter spacers)
650 feet of 14 gauge stranded (insulated) wire
26 inch (by 3) 1/4 inch Lexan (to space Dipoles)
2 48 inch aluminum channels (end spacers)
4 copper grounding lugs
Misc Screws and nuts
Prototype Number Two is done
What you see above is prototype #2 of the N3UJJ/N3UKI Parallel-Cage Dipole
(click the above picture for a full size image)
This picture was taken just after assembly, and it was near the end of the day and it was getting cold
So we called it a day.
Prototype 2 also saw the addition of a DX Engineering DXE-BAL050-H05-A Balun.
You can see the antenna has not been tuned, in fact the new spreader bars have not been installed and tension devices haven't been adjusted.
In the above configuration, (just pulled in the air) the SWR on all 4 bands is well below 2.5
We damaged the coax when the antenna fell to the ground from 65 feet
As soon as we get our JEFA Tech Low Loss 400 we will be ready to do transmission tests
Links that were used to help design this antenna
Resonant Frequency, Bandwidth and End-Effect of a Wire-Cage Dipole Antenna
Many thanks to N3UKI for all the times I've picked his brain
Click here to see my HamShack and RigControl
Click here to see the Antenna Analysis (AIM4170b) of my Antennas
www.sgillis.com | www.sgillis.net | www.n3ujj.com | www.n3ujj.net | Current Location
