Schlatter Family Site

My Amateur Radio Station
W4HH
-- Antennas --

I have three antennas for the station -- and off-center-fed dipole for HF, a dual-band vertical for VHF-UHF, and a Ringo vertical for 6 meters.  Here's a photo taken from the back of my lot looking toward the house -- note the two antennas that terminate on the PVC vent pipe.  The white vertical is a fiberglass VHF/UFH vertical.  At the base of that antenna is a grey box -- that's the balun for the dipole -- look closely and you see two wires radiating from the balun to the left and right.

Off-Center Fed Dipole (OCFD)

This antenna is cut for 80, 40, 20, and 10 meters.  OCF dipoles are resonant on EVEN multiples of their lowest frequency.  Mine is cut for 80 meters, so, it's resonant on even multiples of 3.6 Mhz:  7.2, 14.4, 28.8.

The dipole uses a 4:1 balun that has a 1:1 balun built into the same case.  I feed the antenna with RG-213 coax.

The balun was purchased from Balun Designs -- found here: http://www.balundesigns.com

Here's a picture of the balun.

Inside the box is a 1.5 KW 1:1 balun that isolates the coax from the antenna and then feeds the 4:1 balun also in the box.  The eyelet on the top is used if you hang the balun; the eyelets on the sides are used to connect the two legs of the antenna; coax connector is on the bottom.

Here's a close-up picture of the balun mounted on one of the plumbing vent pipes on my roof, with the two legs of the antenna coming off the balun in a V shape.  The balun is mounted onto a piece of 1/4-inch aluminum stock which clamps to the vent pipe with two U-bolts.  The two legs of the dipole tie to the two side eyelets on the balun -- one leg to each eyelet.  Coaxial cable feed line comes out of the bottom of the balun.  I use UV-resistant nylon zip ties to secure the cable to the vent pipe and provide slack so the cable does not hang with its full weight on the balun or on the end of the vertical antenna.

And here is the layout of the antenna -- I copied this antenna from this link:
http://www.wcerc.org/Projects/ocf_dipole.asp

--rope--insulator--46 ft 9-1/2 inches wire--BALUN--83 ft 2-1/2 inches wire--insulator--rope--
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Coax feed line to rig.

Two ends of the OCF dipole

This antenna is not very high.  As you see in the photo, the balun is mounted onto one of the PVC vent pipes on my roof, about 20 feet off the ground.  One leg of the antenna (the 83-foot length) goes to the roof of my workshop/shed where it terminates about 15 feet off the ground.  The other leg runs to a vertical post made of pressure-treated lumber beside my garage where it terminates only 10 feet off the ground.

In the left-hand photo above is a photo of one end of my workshop-shed.    Look VERY closely and you see a wire, which is one leg of the OCF dipole, coming down from the top of the photo and terminating at the peak of the roof gable.  In the right-hand photo you see the other end of the dipole where it terminates at the garage.  I built a mast of 2X4 and 4X4 pressure-treated lumber and sank one end of it 24 inches in the ground -- my garden hose hangs on the bottom of the mast and one leg of the OCF dipole terminates at the top of the mast.

How does this antenna work?  Here's my experience:

80/75 meters:  Because the antenna is so low, it is a bit tricky to tune on 80 meters.  With the MFJ tuner I am able to get the SWR at the rig down to between 1.5:1 and 2:1 across all but the lowest and  highest ends of 80 meters -- I can't operate below 3.575 or above 3.900.  I believe if I got the antenna above about 35 feet high it would cover all of 80/75 -- but I have no way of getting that much height.

40 meters:  The antenna works well across the entire 40-meter band with SWR 1:1 across the band.

20 meters:  Works well across all of 20 meters with SWR between 1.5:1 and 2.5:1.

10 meters:  Works well across all of 10 with SWR from 1:1 up to 2:1.

VHF/UHF vertical

My other antenna is a Diamond Model XC-30A fiberglass dual-band vertical for 144 and 450 MHz fed with RG-9913 coax.

http://www.rfparts.com/diamond/x30a.html

Six-meter vertical

The third antenna is a Cushcraft Ringo® vertical for the 6-meter band, cut for 50.5 mHz.  Here's a picture of this antenna:

The antenna is 111 inches tall.  It is mounted on a bracket that I clamped to the mast holding my satellite TV dish antenna.  The small Yagi antenna sticking out from the side of the house on the upper right edge of the photo is my Internet wireless antenna.

Ground system

If you go back to the first page and look at the photo of the station where the two coax cables from the antennas come into the window, you can see a #6 copper ground wire coming into the window with the coax.  Directly below the window, outside the house, is an 8-foot long copper ground rod driven 7 feet into the ground.  The #6 copper wire attaches to the ground rod and runs into the station through the window.  I have separate ground leads from the HF rig, 2-meter rig, and antenna tuner tied to this ground wire.  Also, I have Alpha-Delta lightning surge suppressors on each antenna lead with the ground leads from these tied to the copper ground wire.  The end of the #6 copper wire that is in the station ties to a lug that is bolted to the main electrical entrance box -- which is grounded with #6 copper ground wire to two 8-foot ground rods.