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Author Topic: Short Hatted 80M Vertical Dipole  (Read 10631 times)

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Short Hatted 80M Vertical Dipole
« on: February 13, 2004, 10:57:55 AM »

I finally built an antenna that works great for 80M DX-ing. It is a short hatted and center loaded vertical dipole. It is a wire antenna hanging from a tree at 40'. The center section is 36', the hats are 50', and I wound 2 large coils using 10 turns of heavy copper wire on schedule 80 PVC. It has a take off angle of 20 degrees - and is resonant on 3900. I use a little inductance from the tuner in my shack to get it to work well on 3505. No radials to boot!

I just worked A61AJ first call in a pileup - a week ago all I did was blast the local 80M dx-ers with an antenna that was an 88' ladder line fed doublet up only 40 feet - which means its takeoff angle was 90 degrees! A real cloud burner which netted very little dx.

Wow - what a great way to go if you don't have the tall supports to put an 80M antenna up 1/2 wl. And I like it better than the HF2V with elevated radials that I had.

Now I am 37 80M dx entities away from 5BDXCC and for the first time I know I can get there pretty quickly.
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KE6VG

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Short Hatted 80M Vertical Dipole
« Reply #1 on: February 13, 2004, 11:28:13 AM »

Hi Rich. Try using a couple of relays like Force 12 does to switch in extra inductance. This will move you from 80m to 75m at the flip of a switch. And if you are running only one vertical wire. Try and run two or three vertical wires spaced evenly a few inches apart. This will give you more bandwidth to move around in. I still wish I had your trees and acres. hi hi. Force 12 uses vertical wires on thier Sigma 80 along with the aluminum vertical tube. Electrically it makes it look like you are radiating from a fatter tube.
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Short Hatted 80M Vertical Dipole
« Reply #2 on: February 13, 2004, 11:56:13 AM »

Yep - I use 450 ohm ladder line with the ends tied together for the vertical element - I figured that the bandwidth of a short hatted dipole would be very narrow, and it did seem to help quite a bit. I might try the relay idea later - maybe even use the antenna on 80 / 40 and 30, but I turned my old HF2V into a 40 / 30 self supporting hatted vertical dipole (hi hi). I use the Sigma 5 for 20 - 10, and it is fantastic for its size.

These have all worked exceptionally well during this past year with all of the disturbances. I've found the high angle noise rejection to really be great with these antennas. My horizontal antennas were mostly noise all year.

I use a set of K9AY loops for 80M receive - and have even found that the loops worked well on receive on the higher bands when my horizontal antennas didn't.

Of course conditions change and favor one type of antenna over another, horizontal, vertical, loop, etc. It sure is fun playing with antennas and then seeing how they help improve your DXCC "score".

My favorite antenna (at my present QTH) is a half square - which I've used on 20M - but I can't get anything up over 40' - so I haven't tried a half square on 80, 40 or 30. I would like to some day.
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KE6VG

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Short Hatted 80M Vertical Dipole
« Reply #3 on: February 13, 2004, 12:07:53 PM »

Check this out. He runs two of the antennas you are talking about phased. You might find this an alternative to the halfsquare on 80. Read down to the middle of the page.

http://www.iol.ie/~bravo/low_band_antennae.htm
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Short Hatted 80M Vertical Dipole
« Reply #4 on: February 13, 2004, 01:35:53 PM »

Wow - excellent reference, thanks.
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Short Hatted 80M Vertical Dipole
« Reply #5 on: February 13, 2004, 07:33:36 PM »

If you are interested in this antenna, send me an email and I will email you a drawing of the antenna and a digital photo of the center coils.
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NI0C

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Short Hatted 80M Vertical Dipole
« Reply #6 on: February 14, 2004, 10:16:22 AM »

Rich, I heard both sides of your QSO with ZK3SB this morning on 80m.  Your antenna sounds great-- congrats!

73 de Chuck  NI0C
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KE6VG

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Short Hatted 80M Vertical Dipole
« Reply #7 on: February 22, 2004, 01:36:05 AM »

Rich, I'm working with the same problem, to get up a decent vertical antenna for 40, 80. You mentioned not being able to go up over 40'. If you have room, think about that half-square for 80 meters. All you would have to do is take the 66' vertical sections and shorten them down to less than 40' with T loading at the bottom. This is just like your vertical dipole loading. I however, don't have the 132' of horizontal room for this antenna.
I was reading on Cebik's site on loading vertical dipoles and thought I could easily put up a full sized T loaded 40m dipole and use inductors to bring it down to 80m. On his site the fully T-loaded version has unity gain. The coil loaded version is down about -2 to -2.5 db from the full sized version. This would be almost the exact design as the Sigma 80 from force12 at 40' tall total.
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Short Hatted 80M Vertical Dipole
« Reply #8 on: February 24, 2004, 10:13:19 AM »

Thanks to this years ARRL CW DX contest, I am now down to my last 17 on 80M to go for 5BDXCC. Once I've hit that target I will experiment some more. I guess I am more fascinated with DX-ing on the low bands and even trying DXCC QRP because of the challenge, and doing this with limited height for antennas.

The ARRL antenna book has a corner fed 80M half square with the bottom ends folded inward - and I might try that. I have also been thinking about tacking on 2 36' sections of wire onto the ends of the hats and turning the vertical dipole into a "double loop" or slotted loop. Finally, I will try a bobtail curtain using an old Johnson Matchbox or a remote tuner as the LC circuit at the base of the center element. I will also play with a simple inverted L on 80 / 40 and 30 with a really good ground system since its such an easy antenna to put up, and my tree supports are "good enough". I have even thought about trying some kind of "nested half square" arrangement, but am not sure if they could be phased and fed with a single feed line. There are a number of excellent ideas on the cebik.com site and in the ON4UN and ARRL Antenna Book to try - and now I can see that the waning side of the sunspot cycle won't dampen my ability to work DX - since the low bands offer more DX than I ever realized (with the caveat that you have to learn how to be more patient - hi hi).

Anyway - its fun to think and then try.

For now I'll keep chugging along with this antenna and hope that more hams in more entities activate 80M.
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EI7BA

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Short Hatted 80M Vertical Dipole
« Reply #9 on: April 01, 2004, 04:46:33 PM »

I just happened on this discussion, and I'm delighted to see that one of the best kept antenna secrets is out..(:o). I've been using capacity hatted dipoles for a couple of years now..Ever since I read Rudy N6LF's article in QEX. I've worked 133 countries on 160M in two years with a 45ft high version for TX, and a K9AY loop on RX.
  73  John EI7BA   http://www.iol.ie/~bravo/
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Short Hatted 80M Vertical Dipole
« Reply #10 on: April 06, 2004, 08:13:51 AM »

EI7BA - great website, and your progression with these sort of antennas looks excellent.

I just worked my 100th on 80, so I tried a little experiment. Now that I have 5BDXCC and Challenge worked, I wanted to take down 3 of my 5 antennas. A scary thought, but one my XYL would appreciate.

I removed the coils from my 24' short hatted 30/40M vertical dipole (4' hats - all aluminum - my old HF2V hacked up), and replaced them with a short run of ladder line to a remote SGC Smart Tuner attached to my 6' deer fence.

Voila! My first 80 - 10M multiband, automatically tuned short hatted vertical dipole with a 20 degree take off angle.

It isn't nearly as efficient as the monster SHVD I had on 80M, but from 40 - 10 it is excellent. In fact, on 20 - 10 it has less noise and "hears better" than my beloved Sigma 5. The S/N ratio is better, and the "capture" area is about twice the Sigma 5.

So I did take down 2 antennas, and left the 24' SHVD up and replaced the good old 80M SHVD with a G5RV up at 40' (flat top).

I just didn't have the guts to "only" have one antenna - hi hi.
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