How about a fence dipole - Will it work?
Thinking about constructing an HF dipole at the top of a 6 foot high wooden fence. Have 80 feet in the back which connects at right angles to the two sides which are 72 feet and 80 feet long. Could I run an 80 thru 10 meter horizontal dipole fed at approximately the center of the 80 foot section in the back? How long should the elements be? Would I have to run separate wires for each band?
Have a MFJ949E tuner so I should be able to reduce SWR to acceptable levels. If fed with Coax should I use a 4:1 BALUN at the antenna feed point?
I think it's a bad idea.
-Six feet high is very, very low for an HF dipole. Likely to work poorly, interfere with stuff (other electronic items in your house and maybe neighbors' houses) due to proximity, and likely to pick up noise and interference from those same items.
-Six feet high is also "within reach" of almost anyone over four feet tall, and there are dangerous RF voltages at the ends of a doublet antenna when you transmit, even with 100W. Or less. An antenna used for transmitting shouldn't be within reach, unless perhaps it's a mobile antenna where it's very unlikely someone's running alongside your car holding your antenna as you transmit. You can get a nasty RF burn from a 5W hand-held with a metal whip, if you touch it in the wrong place while transmitting, but at least that won't affect "others."
I'd shoot for something higher and completely out of reach.
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I disagree. I think it's a horrible idea.
Originally Posted by WB2WIK
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The antenna will not perform very well. However, if such an antenna is all that you can get up, then such an antenna is definitely better than no antenna!
Certainly it wll listen poorley and warm the worms when you tx , just make a beverage for rx as nothing horizontal that low wll function wlll
Originally Posted by AB3OL
Many years ago having read an article in Practical Wireless magazine about an amateur who made a dipole which was 1 metre above ground, I decided to try it.
I made a dipole fed with RG58 brought it into resonance on 20 metres and had contacts into Germany about a 1000 miles away.
Some years later using another dipole 90 ft long, 8 feet above ground, fed with 300 ohm ribbon feeder and a 4:1 balun I made a PSK contact on 80 metres one evening using 25 watts and made a contact with the south coast of Spain which is 1,500 miles away.
So it is possible to make contacts on low dipoles, but its much better if it can be 30-60 feet above the earth. I recall there either is, or was, a contest in the US where hams used odd things to use as antenna's like garden tables, aloominum garden chairs etc and some people made some good distances.
My advice, if its all you can do, give it a try, nothing ventured, nothing gained
Very low horizontal antennas are great on 40metres for Near Vertical Incidence Skywave ...NVIS. This is recognised by the military, you can just bounce your signals off the sky above and have them bounce straight down within a 1000 mile diameter of your QTH. You don't need a tall mast, bells and whistles etc and none of it is obstructed by mountains, jungle or buildings.
40 metres daytime is used for ragchewing in the UK.
Good luck with the fence antenna, but yes, get too high for people to reach -or maybe put up some DANGER OF ELECTROCUTION signs ha ha, .....should impress the neighbours!!
You will make some contacts but luck, not signal strength, will be the main factor.
I had a temporary 30M dipole antenna at a motel for a week on a wooden fence top, and at 7 ft high I was able to QSO Europe and the west coast a few times with my MFJ QRP rig on 30M but many MANY CQs went unanswered.
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Put the antenna on the fence. I had a 80-60 fan dipole at 8 feet with the ends bent back because my lot was too narrow. It ended up in a u configuration and I worked Europe from south Florida more than once on both bands and it was awesome within 500 miles for US ragchews due to its NVIS actions. Even though it was NVIS one still recieves all angles of incoming signals and since antennas work both ways when I heard dx I usually could work them. Ed KJ4NT