TWO ELEMENT PHASED VERTICAL SYSTEM
I have always been curious about vertical antennas and how to make them
efficient. Not having a lot of room for 40 meter beams, I decided
to use the space I do have, which is a long wooded fence in the
I started by building a 40 Meter 1/4 wave vertical using aluminum
tubing, then I made a second one to Phase with the first one. The
following photos and writeup are the results.
Each antenna is installed and tuned to give a 1.1:1 SWR at the antenna
connector of each Vertical. The Feed and Phasing cables are
added. The finished system
performs well and has very good Front to Back nulls. The SWR is a
1.7: 1, which is a little
high, but I use a Tuner to make the amplifier happy!
The Two Verticals are
spaced 32 feet apart.
They are elevated about 6' above
ground and have two radials each. These are also elevated, so
required. The most difficult things about antenna phasing is
tuning the two antannas the same and coming up with the proper Coax
lengths for the feedlines and phasing delay line. The actual
length can be
MFJ-269 Antenna Analyzer Advanced
The math to find the coax lengths is shown below.
You Can Use a MFJ-259 or MFJ-269
to Measure the lengths in Degrees and verify the lengths....
Relay Box Showing Connections
These 12 VDC Relays Are The Type That Can Handle 5KV On The Contacts
The Relays are: AMF/ Potter-Brumfield, 12 VDC, Model KT11D or equil. If
these ever crap out, I will change to 12 VDC Vacuum Relays.
40 Meter Vertical SW and Two Elevated Radials
Free Standing Vertical
40 Meter Vertical NE Antenna, Fiberglass Rod is the Very Strong
Relay Box With Lid Off Showing Connections
Note: I use teflon wiring for hookups.The Ground Strap is the Safety
Ground to a Rod.
Taped Up Coax Connections, Ground Strap Goes to Ground Rod Below.
TWO small holes are drilled in the bottom as Weep Holes.
Weather RAIN Cover In Place
Finished Box With Lid On
The Antennas Need A Way To Bleed Off Static Buildup.
So I Added a 2.5MH choke from the Antenna Radiator to Ground.
These are available on Ebay or RF Parts.
To Protect The 2.5 MH RF Choke from Rain and Ice, A Plastic Cover
and Taped to secure.
A Control Box In The Shack, Switches The Three Different Antenna
On/Off Switch on the Left, Power On LED in the Middle and the
Position Switch on the Right.
This is constructed in a small HAMMOND die cast box 2" x 4" x 1" and It
is Secured Under My Operating Table.
The Over All SWR is between 1.6 : 1 and 2.2 : 1, So
The Coaxial Cable is routed through the Vectronics HFT-1500 Antenna
Tuner to Make the Amp
Happier ! It now sees 1:1 SWR.
The End !