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1/2 wave Inverted V Dipole Antenna

Alabama Buckeye

Dogma Heretic
Jul 29, 2022
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Magic City Alabama
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Jul 12, 2022
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Do you have trees on your postage property? A tree limb 18-23' AGL is fitting for a nearly invisible I-Vee antenna. I say 23' to accommodate the 5' vertical depth of the I-Vee; therefore, the entire antenna is 1/2λ AGL. Your choice of 20w will work splendidly for 16 AWG wire or up to 12 AWG I-Vee antenna. The only need for 12 AWG in the case of 25W output would be strength against storm winds.

Hang it from the limb using a small single pulley attached to end of throw line.
Though the pulley run a seconding line to raise and lower the antenna as needed.

A 90 or 106 degree I-Vee will be about 5' in the vertical height above your leg spreader. A 90d I-V will have a leg spread just shy of 12', while a 106d spread will be 13.18'. Leg spreader may be 1/2"D wooden dowel section with 1/2"I.D. pipe segment (copper) connectors. Or 1/2" camo painted PVC with single or multiple segment connectors. Use 550 paracord strung from ends of spreader to ground weights, I use repurposed brake rotors, to tether antenna against Colorado winds. The center fed coax dangles perpendicular to spreader center and affixed to spreader to insure no sag; also eliminates coax weight on connector.

A choke balun of the usual "Fugly" nature will be far more conspicuous than a 1:1
http://www.vk3bq.com/2014/09/24/11-current-balun/ current balun made in the manner shown. In the referenced build the author uses coax. Coax is not necessary. A 48" of repurposed extension cord is usable; just keep track of + and - strands; mark the ends.
Tested my I-Vee yesterday with and without the 1:1 balun with the leg ends < 10' AGL. Supposedly at this height the need is NIL.
Without: 1.5W dead key 1.05:1 swinging to 13W and 1.15:1.
With: 1:1, 1.5W swinging 13W.
I might add, the 1:1 balun is wound with 16 AWG magnet wire chassis rated for 100W continuous; at 13.7 VDC. I have been using it and modulating, very briefly, upwards of 1200W without smoking it.

Build a 1:1 balun with FT240-43 with dual strands at 7 wraps each direction. Mount within 3D printer made PETG frame having nearly the height of an
SO-239, with the length and width minimally necessary to frame the wound toroid, mounted SO-239, connectors to affix antenna legs, and a small eye-bolt to hang it with. 100mm L x 75mm W x 25mm H. Frame is open to the weather across the broadsides.

I don't believe you need concern yourself with RFI and the neighbor's radios with 25W of RF power. As I understand it, your coax is the radiating entity that emits the RFI that may cause interference. Your coax with a low or balance SWR should not cause a problem. A choke's purpose is to minimize if not eliminate any that may occur.
Thank you I have my dipole up at 9 ft (tried 14 ft. Same thing happens)with the legs spread at about 100° and I can't get my srw below 3. If I lower the center of the dipole about 5 ft off the ground the swr goes to 1.5 and I don't know why that's happening. But I cannot seem to get the Swr under 3.0 I receive ok,I can hear people talk. Tried radio check a few times and nothing. Didn't want to keep transmit with 3.0swr
 
Jul 12, 2022
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As said above, you're probably gonna have bad SWRs. All Dipole-based antennas along with verticals, want to be in "Free Space" with nothing around them within 1/4 wave .... which is your 9 Feet for 27mhz. You can try it and see what happens. All installations are different .... but I would expect problems. An alternative would be a Loop. Loops are current-point antennas and ignore nearby objects. You could run a Loop all around your house attached to the soffets/facia below the gutters in whatever shape you house is - square, rectangular etc .... Because this will be a considerable length beyond a full wave of 11 meters you should see some gain - and the antenna will operate on much lower bands if you are a ham. You will need a 4:1 Coaxial Balun and an Antenna Tuner for typical operation.
I will hope your I V as planned works for you.
Thanks for your reply. It all helps.and I do have problems with it. Can't get swr below 3. And can only get apex to 14 ft. Some one said I should be at 9 ft. Cuz it's a multiple of a full wave?
 

Alabama Buckeye

Dogma Heretic
Jul 29, 2022
245
198
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Magic City Alabama
Thanks for your reply. It all helps.and I do have problems with it. Can't get swr below 3. And can only get apex to 14 ft. Some one said I should be at 9 ft. Cuz it's a multiple of a full wave?
You lowered 100d I-Vee apex to 5' AGL, the legs ends would be on the ground and your SWR is 1.5:1. There's a clue in that. para 5 below.

9' might have been misunderstood. Wild Weasel spoke of 9' distancing from reflectors, I believe was his inference. And this was when you were speaking of attaching it to house eve.

Seriously consider the pseudo-free swinging tree limb alternative. There is so much flexibility available to you. It is possible to raise an I-Vee with very little or zero street view. The horizontal leg spreader is the only component that is barely viewable, if suitably camouflaged. Sky blue and partly cloudy horizontal line in the air on a rainy day? Who's looking?

Lets talk about SWR channel 1 V channel 40? My first thought, after ascertaining both upper and lower channels are reading equally 3+, is the manner of construction.

What are your leg lengths? Equal 1 & 40 3+ SWR, too long? 5$ bet!
Use those I-Vee calculators posted back 0n 31 Aug.
Add 6+" for sake of play and fold over, and just cause you mite decide 135d I-vee is your flavor for the day.
If I recall I had very similar 3+ when starting. Too long in the legs. Folded over maybe 2" and I was on my way again, toward fine tuning. Unequal leg lengths is impotent.
Soldering would be my 2nd assessment. If you're using ring connectors solder them as well.

The highest SWR I see on my 90d I-Vee at maybe 15' AGL is 1.45:1 with 1200W.
With most of it hidden by tree foliage; which, BTW is not good on rainy days.
 
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Alabama Buckeye

Dogma Heretic
Jul 29, 2022
245
198
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Magic City Alabama
I don't recall where you are residing, if not on a rock slab here is a suggestion:

Drill a hole 2' deep absolutely perpendicular, insert 20' top chain link fence rail, I think they are 1 5/8" OD.

Drill a hole with your garden hose water pressure. Attach 2-3' of hose end to a mop handle. Use carpenter level to maintain plumb. Hit a rock or root? No problem move over several inches or a foot. It is easier with a custom drill head, with teeth, but a high pressure hose end nozzle is quite helpful.

Insure perpendicular/plumb while you beat the ground vigorously around the gap between pole and earth. It's now in the ground solid. A tiny bit off plumb won't hurt. Could insert a 2"D x 2' PVC section, in the ground and pound it in firmly. , Hole should be wide enough, if not insert drilling rig through 2" PVC and drill again. Insert top rail into PVC; pipe is removable. I grease up the lower 2' of pipe, makes for even easier removal.

At upper end of pipe dill hole and insert I-bolt with 1/4" rope pulley. You now have 1/2λ AGL attachment for your 360d directional I-Vee, 9'+ away from the house. Use appropriate color 1/4" Dacron line (last for many years), put a cleat on the post and hoist up the antenna. No more visually offensive than flying an upside down flag.
Use 1/2 dowel or 1/2" schedule 40 PVC ~ 13' full length leg spreader, I don't know which is lighter, PVC is cheaper. Anchor ends of leg spreader as you deem fit. Leg spreader and 18' standing pipe are your only wind loads. For sure a very strong wind will cause sway but it's not going to break or fold over. You didn't mention you lived in tornado alley or hurricane landing zones. If so you've bigger problems to deal with.
 
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Wire Weasel

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Dec 13, 2008
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Thanks for your reply. It all helps.and I do have problems with it. Can't get swr below 3. And can only get apex to 14 ft. Some one said I should be at 9 ft. Cuz it's a multiple of a full wave?
Hi NSG - I believe it is having the "anticipated" problems because you are attaching it directly against the house. Such an antenna problably won't be happy unless it is Stood Off 9 feet from the house ..... so it is not touching the house. It wants to be in Free Space - at least 1/4 wavelength away from nearby objects.
 
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Jul 12, 2022
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Hi NSG - I believe it is having the "anticipated" problems because you are attaching it directly against the house. Such an antenna problably won't be happy unless it is Stood Off 9 feet from the house ..... so it is not touching the house. It wants to be in Free Space - at least 1/4 wavelength away from nearby objects.
Thank you for your reply, what about sloping it from peak to middle of yard away from house instead of vee or straight dipole? Should positive be up or put neg.lead up? Thanks again for sharing
 
Jul 12, 2022
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You lowered 100d I-Vee apex to 5' AGL, the legs ends would be on the ground and your SWR is 1.5:1. There's a clue in that. para 5 below.

9' might have been misunderstood. Wild Weasel spoke of 9' distancing from reflectors, I believe was his inference. And this was when you were speaking of attaching it to house eve.

Seriously consider the pseudo-free swinging tree limb alternative. There is so much flexibility available to you. It is possible to raise an I-Vee with very little or zero street view. The horizontal leg spreader is the only component that is barely viewable, if suitably camouflaged. Sky blue and partly cloudy horizontal line in the air on a rainy day? Who's looking?

Lets talk about SWR channel 1 V channel 40? My first thought, after ascertaining both upper and lower channels are reading equally 3+, is the manner of construction.

What are your leg lengths? Equal 1 & 40 3+ SWR, too long? 5$ bet!
Use those I-Vee calculators posted back 0n 31 Aug.
Add 6+" for sake of play and fold over, and just cause you mite decide 135d I-vee is your flavor for the day.
If I recall I had very similar 3+ when starting. Too long in the legs. Folded over maybe 2" and I was on my way again, toward fine tuning. Unequal leg lengths is impotent.
Soldering would be my 2nd assessment. If you're using ring connectors solder them as well.

The highest SWR I see on my 90d I-Vee at maybe 15' AGL is 1.45:1 with 1200W.
With most of it hidden by tree foliage; which, BTW is not good on rainy days.
8.3 foot legs,soldered good. I just put it up as a slope and swr came down to 1.3 and 1.5 ,my cb is pushing 5 watts .I can hear Florida, Washington,Dallas.....but no local chatter? Thanks for your help. I'm glad to see a forum with nice people. Some of these forums are not so good....thanks again.
 
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Alabama Buckeye

Dogma Heretic
Jul 29, 2022
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Magic City Alabama
8.3 foot legs,soldered good. I just put it up as a slope and swr came down to 1.3 and 1.5 ,my cb is pushing 5 watts .I can hear Florida, Washington,Dallas.....but no local chatter? Thanks for your help. I'm glad to see a forum with nice people. Some of these forums are not so good....thanks again.
8.3 foot legs,soldered good. I just put it up as a slope and swr came down to 1.3 and 1.5 ,my cb is pushing 5 watts .I can hear Florida, Washington,Dallas.....but no local chatter? Thanks for your help. I'm glad to see a forum with nice people. Some of these forums are not so good....thanks again.
What do you mean by "slope"; as opposed to what, an Inverted-V?
 

BJ radionut

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15-Sloping-Dipole-Antenna.jpg




 
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Wire Weasel

Senior Moment
Dec 13, 2008
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You can do the Sloper and it should work .... just keep in mind that all these sorts of short wire antennas you can considering and trying to make work .... and being relatively low to the ground - don't expect them to Kick Ass. Locally or DX. You will not be Running With The Big Boys in the area ..... but I realize that you are trying to put something up that will work to get yourself on the air.
 
Jul 12, 2022
57
47
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You can do the Sloper and it should work .... just keep in mind that all these sorts of short wire antennas you can considering and trying to make work .... and being relatively low to the ground - don't expect them to Kick Ass. Locally or DX. You will not be Running With The Big Boys in the area ..... but I realize that you are trying to put something up that will work to get yourself on the air.
I did turn my inverted V into a sloper and picked up and talked to the big boys locally and heard all kinds of skip today that we never heard before . It was very cool.you're right I'm not going to get out very far but I'm going to throw one of them little Italian amps on it and hopefully get at least 10 to 12 miles out. I live in hoa community that sucks. So I need to be stealthy. It's coming of the back peak of my house sloping towards town. It worked. Wife's happy. How do I check dead key and swing watts? I have workman 3p cheap meter with dual swr and watt. But when I talk into mic, watt meter stays at 4.5 watts...even when I scream into it.lol any thoughts. Thanks for sharing
 
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