Small garden Antenna for HF bands

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Re: Small garden Antenna for HF bands

Post by Mark-in-Essex » 25 Jan 2013, 14:08

I have a brand new Hustler BTV6, I don't think I will ever get around to using it. Any good to you Paul? I'm sure we could do a deal if you like Image

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Re: Small garden Antenna for HF bands

Post by CookieRaider » 25 Jan 2013, 17:29

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Re: Small garden Antenna for HF bands

Post by NoiseBoy » 25 Jan 2013, 19:20

Monsta wrote:
and for longer bands the inverted L for small spaces..you can get 40/80 out of these puppies and many hams work the world on these and swear by them ...they are sadly slighly directional on their lobes ..so you need to orientate them correctly, ideally you are looking at (as you know) NNW-SSE or NNE-SSW

http://www.clive.wankling.dsl.pipex.com/l.html

none of the above are "compromise" antennas, full of hats, traps, coils and all that other bullshine trickery that means you are not getting bang for buck and WASTING all your power heating hardware ...and thats why you hear about these QRP guys talking the planet on a wire ad 10 watts ...(makes you sick). Also none of the above require multiple grounding wires / RF earth webs ..(except for the copper rod)

i have seen monstrous HF verticals that are utter tripe without good RF arrays, to resonate with and you might find your wife gets a little upset with you burying 20 wires in the lawn ...I mean it makes all the difference ...but by god its a pain in the prostate without a big garden ...


Do it!
Feeding an unbalanced antenna against an earth rod just doesnt work. That antenna would be so much more effective with proper ground radials, even if it was just one resonant for each band and on the same side. Inverted L's do seem to work very well for what they are if done right.

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Re: Small garden Antenna for HF bands

Post by northern35s » 25 Jan 2013, 21:33

NoiseBoy wrote:
Monsta wrote:
and for longer bands the inverted L for small spaces..you can get 40/80 out of these puppies and many hams work the world on these and swear by them ...they are sadly slighly directional on their lobes ..so you need to orientate them correctly, ideally you are looking at (as you know) NNW-SSE or NNE-SSW

http://www.clive.wankling.dsl.pipex.com/l.html

-------------.


Do it!
Feeding an unbalanced antenna against an earth rod just doesnt work. That antenna would be so much more effective with proper ground radials, even if it was just one resonant for each band and on the same side. Inverted L's do seem to work very well for what they are if done right.
I don't think the chap who wrote the article understands where his return current comes from:
Because of the rain and soil blessing, a good r.f. earth is assured with only a single one metre long earth rod.
Most of it doesn't come from his earth rod, but the coax feeding his wonder antenna, tsk tsk tsk.


As for directivity, an inverted L doesn't suffer too much from this as can be seen below:

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On the left if the polar view and on the right is a 2D slice, around 1.5dBi less in the direction of the L

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Re: Small garden Antenna for HF bands

Post by crusty » 25 Jan 2013, 22:16

Is that plot for a base-fed? If so, run that same antenna @ 40 and 10m. Base-fed inverted L's get goofy as a multiband. The frequency at which it starts to resemble a cap loaded vertical is a build consideration.

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Re: Small garden Antenna for HF bands

Post by northern35s » 25 Jan 2013, 22:28

crusty wrote:Is that plot for a base-fed? If so, run that same antenna @ 40 and 10m. Base-fed inverted L's get goofy as a multiband. The frequency at which it starts to resemble a cap loaded vertical is a build consideration.

On 40m it resembles a football, 20m is again omnidirectional with some funky nulls, and 10m has around 6dBi gain in line with the L, but at an almost useless angle of 40 degrees
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Re: Small garden Antenna for HF bands

Post by crusty » 25 Jan 2013, 22:45

I read an article where the author got improved results on higher frequencies using a single trap. Can't recall where I saw it though sadly.

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Re: Small garden Antenna for HF bands

Post by Monsta » 25 Jan 2013, 22:53

i am no antenna genius...

but i do KNOW these small inverted L's do work!
and yes with no radials .....as long as you get a good earth rod in

it is however true they are target-ted at 40m, but will work on 20m and other bands also,
there are guys around here with X beams and cubes and quads in the air on Versa's etc
and they sill have not abandoned these inverted L's ....so there must be something in it

but like i said for limited space omni, you can't do better than a cobweb, with a vertical for 10m of you can get away with it
..the plus with the L is that once its up its almost invisible
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Re: Small garden Antenna for HF bands

Post by northern35s » 25 Jan 2013, 23:44

crusty wrote:I read an article where the author got improved results on higher frequencies using a single trap. Can't recall where I saw it though sadly.
The antenna I modelled was a single band 80m antenna, if I find the time I'll have a go at modelling a trapped version, it would interesting to see the results, but as I'm now on my iPad I'll leave until another day. Of course patterns change dependant on the radial system employed, with the antenna above I purposely modelled it with absolute minimum ground in an attempt to replicate the article.

Monsta, the reason people will have an inverted L as well is because it's an efficient use of space for the likes of 80/40m, I like to think I've got a large back garden that is until I think about installing an 80m doublet, it would have to go over the roof of the house, an inverted L with radials would be much easier to install ;)
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Re: Small garden Antenna for HF bands

Post by uk197 » 26 Jan 2013, 09:18

I have a tiny garden and use a 10m tall fibreglass fishing pole with a wire up the middle, random bits for radials, its a nice 1/4 wave for 40m (no tuner required) and tunes up nicely as a 1/2 wave vertical for 20m too. Its pap on 80m, but I've worked the world on 40 and 20 with it.... I have a lot of time for verticals, they seem to be deaf to europe and great for DX.

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Re: Small garden Antenna for HF bands

Post by northern35s » 26 Jan 2013, 10:31

uk197 wrote:I have a tiny garden and use a 10m tall fibreglass fishing pole with a wire up the middle, random bits for radials, its a nice 1/4 wave for 40m (no tuner required) and tunes up nicely as a 1/2 wave vertical for 20m too. Its pap on 80m, but I've worked the world on 40 and 20 with it.... I have a lot of time for verticals, they seem to be deaf to europe and great for DX.
What do you use to match the antenna on 20m?
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Re: Small garden Antenna for HF bands

Post by bigtee » 27 Jan 2013, 15:44

Do you have a loft space you can use?

I have my Carolina Windom in mine nailed to the roof joists and the wire antenna nailed to the wood slats it works fine worldwide into Japan last week. it's 40-10m.

Cobwebb another good one as mentioned.

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Re: Small garden Antenna for HF bands

Post by uk197 » 27 Jan 2013, 18:00

northern35s wrote:
uk197 wrote:I have a tiny garden and use a 10m tall fibreglass fishing pole with a wire up the middle, random bits for radials, its a nice 1/4 wave for 40m (no tuner required) and tunes up nicely as a 1/2 wave vertical for 20m too. Its pap on 80m, but I've worked the world on 40 and 20 with it.... I have a lot of time for verticals, they seem to be deaf to europe and great for DX.
What do you use to match the antenna on 20m?
MFJ auto-tuner. Oh I'm also quite anti-balun/unun too :)

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Re: Small garden Antenna for HF bands

Post by northern35s » 27 Jan 2013, 20:46

uk197 wrote:
northern35s wrote:
uk197 wrote:I have a tiny garden and use a 10m tall fibreglass fishing pole with a wire up the middle, random bits for radials, its a nice 1/4 wave for 40m (no tuner required) and tunes up nicely as a 1/2 wave vertical for 20m too. Its pap on 80m, but I've worked the world on 40 and 20 with it.... I have a lot of time for verticals, they seem to be deaf to europe and great for DX.
What do you use to match the antenna on 20m?
MFJ auto-tuner. Oh I'm also quite anti-balun/unun too :)
I was interested as the impedance of the antenna will be very high on 20m, where it's a 1/2WL, sometimes tuners can struggle to match the high impedance, do you have a long run of coax and what type?

Questions questions and yet more questions, I'm always interested to know what people use, nosey I guess :mrgreen:
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Re: Small garden Antenna for HF bands

Post by uk197 » 27 Jan 2013, 21:13

about 10m of westflex for that aerial matey

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