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Bob tail curtain or Half square opinions

wavrider

wavrider

W9WDX Amateur Radio Club Member
Jun 2, 2009
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1,378
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Fall is coming soon if one can say that Florida has a fall season, so cooler weather will be here and that is antenna building time.

I have been researching the bobtail curtain and the half square antennas for low band DX verticals.

Any one have any experience with the above antennas, likes dislikes etc.etc.

Opinions, comments are appreciated.
 
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I'm using just 1/4 vertical with elevated radials, before winter I want to rebuild that to two phased vertical system as ON4UN described.
Mike
 
wavrider said:
55 views and no replies? Looks like no one uses these antennas.
Click to expand...

I have a half square cut for 11 meters. Even though it makes a good match, I don't think it is effective at 11 meters. In order to keep the vertical 1/4 wave elements close to the ground the horizontal 1/2 wave does not get high enough. I think it might work much better if designed for much lower frequencies.
 
Marconi said:
I have a half square cut for 11 meters. Even though it makes a good match, I don't think it is effective at 11 meters. In order to keep the vertical 1/4 wave elements close to the ground the horizontal 1/2 wave does not get high enough. I think it might work much better if designed for much lower frequencies.
Click to expand...


Both the half square and Bobtail Curtain do indeed perform better on the lower bands like 160-40m if you have the room. They are hard to beat for the money on 40m if the pattern is where you want it.
 
Thanks for the replies.

What I have read about the bobtail is it is bi directional, but not very broad banded.

I have seen three and four vertical elements on different bob tail configurations.

I also seen different feed methods, one is fed at the center vertical with a matching network, the other is fed at a corner where the vert element meets the horizontal 1/2 wave phasing wire with no matching network needed.

Cleared some trees today from the back 40 so I would have the room for the bob tail, told the XYL I was cutting fire wood for her fireplace this winter, maybe she will make a cake, in reality I was clearing a path to that 70 foot pine tree.:ohmy:

I will post the results when I get it up and running, try 40 meters first, if I like the results I will try one for 75 meter phone.
 
BOBTAIL ANTENNAS Best kept Secret of Ham Radio

Bobtails are simply the best kept secret of the last fifty plus years. I have been building and using them for years from a simple 3 element to many elements. The traditional bobtail has about 6 db gain bidirectionally and an extremely low take off angle of about 18 degrees depending on who you read. It does not have to be mounted high, in fact, all my bobtails have been at ground level, the tails a few feet or touching the ground. They are also very broad-banded, but typically only work for the band they are designed for. With my 5 element 20 meter I can usually hear Europe an hour before most stations are working Europe. Using 100 watts I can work anything I hear, using 5 watts I can usually snag about one out of two Europeans, and with a half watt I can work about one out of four or five Europeans. I have worked the world though with half a watt and my bobtail antennas. I sent a 3 element to a friend stationed in Iraq, and I using likewise on 40m a 3 ele bobtail with 300 watts, he said I had the best signal he had ever, repeat ever heard from the states. These antennas are not difficult to build. I sell a huge selection of them on Ebay, but you don't need to buy one from me to find out the wonderful results this antenna produces. Get some wire and start building. I swear, it is the best wire antenna out there, and to be quite frank, for the low bands where it is difficult to get a good dx antenna, you can't beat the bobtail, it will run circles around the yagis, etc. Incidentally, all you need are two trees or masts 135 feet apart, and about 34 feet tall. Throw a rope in the tree, pull one end up, go to the other tree, and throw the other end up and pull it up. You now have a 3 element 40 m beam with a super low, dx producing angle of radiation. I sell a switchable version, where you can beam N&S or E&W at the flip of a switch. Seriously, if you build it, they (DX) will come. 73 John W3IK "The Bobtail Guy"
 
John,

That is what I was hoping to get, feedback from someone that had used it, not armchair antenna analyzer's who pick apart an antenna based on theory.
One's that have never cut a finger or scraped a knuckle actually building one.

Thanks for your support to the troops over there in the sand pit.

I got the 70 foot Rohn 25 tower in the air yesterday, it is a few hundred feet from the pine tree I plan on using for the other support.

The tower will use a hazer to raise and lower the TA-33 and the Multi-band vert up and down. I will install a couple of pulleys to raise and lower the bobtails with so everything is coming together.

The interest in bobtails came when I was working a French op on 40, he was using his dipole, then switched to a bobtail, it was as if he turned on a Contest amplifier, it was incredable the difference in signal strength.

Thanks for the info and advice, I think I have seen your bobtails on Ebay, nice antenna.
 
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I'll chime in with my .02 on this subject. I use a half-square on 40m and it works very well -- as long as the other station is in my signal path. I've found it to be very directional and weak off the ends, as it should be. This fall I plan to extend it to a full bobtail, adding the addtional vertical to the end.

I feed mine at the top of one corner using 50 ohm coax and a current balun. Mine may be higher than it needs to be. The top/horizontal section is about 55' and the tails about 20' off the ground.

As with any vertical, I think location and proximity to other structures can play a big role in the performance of an vertical with the base at ground level. If I lower my half-square so the tails are near the ground I think my house and garage are likely to decrease performance. Thoughts on this anyone?

In my location I have another wire antenna that performs better than the bobtail -- it's a plain 40m dipole up 85' between two oak trees. It's 85' up standing directly under it, but in the Europe direction about 50' from the antenna it's about 110' up because I'm on a hill and that side slopes down very steeply.

Look forward to more discussion on this topic.

73,
Milt - WA4FNG - Atlanta
 
Sounds like a great di-pole location, the height is the key. Might be more like a slope rif it slopes downward in direction of EU.

I never had that much luck with a dipole on 40 for DX, but highest I ever got one was 65 feet to the feed point. Inverted V not a flat top.

I will listen in an some 0's and 1's working EU on 40 running a di-pole, but they are 1000 miles North of me and skipping across the pond.

A friend of mine uses an lazy H strung between two towers, he claims it is a screamer in the direction of the radiated signal.

It will be intersting to see how the dipole compares to the bob tail when you get the bob tail up. That bob tail may allow you to worker further into NE EU than the dipole.

I can not say how the structure will effect the bob tail, but if it follows typical RF theory then it will effect it in reflected, refraction or filtration of the radiated signal.

That will be a good comparision, especially with the height at your QTH.
 
Yes, the dipole is facing EU (northeast for me) and works well at 85'. Recently, I discovered something about my half square - it transmits better than it receives. Many times I switch over to a Delta Loop or the dipole to listen, then switch back to the HS to transmit. I have confirmed on several occasions they could hear be stronger on the HS, but not the Delta or dipole. The reverse would be opposite for me.

With 3 antennas on 40m I often switch to the "loudest" antenna on receive before answering a CW. I'm not talking about long distance DX, but maybe Atlanta to Seattle. The HS faces that direction and many times the W7 station will be louder on the other antennas. When I reply to a CQ they don't hear me, or I'm very weak until switch over to the HS. Crazy.

On more than one occasion I get great reports off the end of the HS -- not supposed to be great off the end, but propogation is wierd stuff sometimes.

Keep me posted on your project - I would love to hear about your Bobtail. I don't think I'm going to add another tail to mine -- thinking more about just building another one that faces the other direction.

Also, the recent slew of activity down in PJ-land resulted in several good contact with them using the Half Square - busting through several pile-ups.

73,
Milt
 
Thanks for the update and yep propagation is weird.

sounds like you got a winning combination on the loop for recieve and the HS for tX.

I used to use my 160 full wave loop for recieve and tX off the 80 meter vertical. worked good for dx.

I put time into building a multiband dipole, some would say fan but feed point is diferent, I managed to get 15 through 160 out of it.
20.40.80. and 160 cut to freq with 15 as a harmonic off of 40 meter.

I have been working the PJ's on 15 for the last week, got Sao Pablo in the log tonight. Ja land is also on 15 on the weekends around 5 pm local here in N. FL.

I have everything ready for the bobtail so maybe this weekend I will start on it. cooler weather sitting in so it is wire experimenting time.
 

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