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High SWRs with Dipole

2RT307 said:
Congrats on making a contact! :thumbup:

Your SWR's indicate the antenna is long. Shorten each end by folding the wire back, about an inch at a time. You should see them come down when you recheck. Don't cut it though! Just fold it back.

73,
RT307
Click to expand...

Thanks I'll try to shorten it like you said. Hopefully that will do the trick.
 
Basics:
There are two things that determine how 'good' any antenna is. They are resonance and impedance matching. The first is determined by it's length, or loading. The second is determined by a combination of that antenna's normal input impedance and a means of making that normal impedance closer to 50 ohms which is typically the impedance of the rest of the antenna system.
Resonance determines how much of the power reaching the antenna is radiated. Impedance matching (SWR) determines how much power -get's- to the antenna to be radiated. Both are important.
Length/loading determines resonance. You want it as resonant as possible. That doesn't mean that a perfectly resonant antenna is going to put a signal where you want it to go, it's radiation pattern does that and is determined by the placement and type of antenna. It only means that all of the power/signal reaching that antenna get's radiated.
Impedance matching/SWR says how much power/signal -gets- to the antenna to -BE- radiated. One of the things that affects that impedance/SWR matching is height above ground. That seems to be (one of) your problem in your particular situation with it's limitations.

Height above ground does affect the length of an antenna. By raising yours some you lowered the SWR to a more acceptable level, which shows that height is still an option.
Another way of lowering SWR (matching impedances) is by drooping the legs of a dipole, not really making into an inverted 'V', but just lessening the angle between those legs. A dipole is an 'easy' antenna to work with when dealing with resonance and impedance matching. They do require some room for maneuvering it into a position where both of those qualities are optimal (resonance/SWR), if you've got that room then it isn't too much trouble. If you don't have the room then I think I'd start looking into other style/shapes of antennas.
There are no 'perfect' antennas that do everything asked of them in any place that they are placed. There are only antennas that can be 'good' in each particular situation within the limitations of that particular situation.
Good luck.
- 'Doc
 
I raised one end of my dipole up to about 12 feet and it now droops down to about 10 feet on the other end. Today California was coming in good and I made several contacts. Talked to 144 in Death Valley for a couple of minutes on LSB 37 and some short contact to L.A. and Fresno Cali. I heard a station out of Hawaii but did not have luck getting him.

I also talked with a guy only about 100 miles north of me, not sure how that worked.
I talked to a couple of stations out of Arkanas, Missisippi, and talked with a station out of western Tennesee for a few minutes. So I just want to let anybody else who cannot run a nice base antenna know that a dipole will work. Of course mother nature is 90 percent of it. And I can only get out 4-5 miles locally, but that is ok since I just want to talk DX

One guy out there was trying to tell us all how dumb we were on SSB, because we simply learned how to use a clarifier but had no idea what to say once we actually contacted somebody after hours of trying. I like to talk to somebody if we have a good contact going,but many time it is a simple hello and goodbye..

Why don't more people use LSB 35-40 when LSB 38 is so busy?
 
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I had just moved house and wanted an antenna up and working as quick as I could, I made a speaker wire dipole, including feedline choke, for the 20m band and hung it up around 7' for testing, well it stayed like that for over a year until I put up something a little better, I worked into East and West Coast USA, SE Asia and into Australia, yes a dipole will work at 7' high, but I'm not going to kid you all into thinking that it's perfect.

As for height, I modeled an 11m dipole at various heights, I couldn't get a significant VSWR shift between 7' and 30', the only time it shifted dramatically was when I stuck at ground level.
 
I got it to work pretty well. I ended up folding the antenna on itself and taping it to get good swrs. Plus mounting at 12 ft to the feed point in an inverted v or a slope mounted at about the same heighth, worked good for dx.

I have even had the dipole mounted indoors across the ceiling with some success. I have been using the boomerang antenna now for quite a while due to it taking up less space in my small patio.

Before the sirio I used a dipole mount with two fiberglass antennas as well. I believe the boomerang works best for my current home situation.

I need to try the wire dipole again when I have time to.


Here is a video a got of using the inverted v. Talked a little bit local and made a couple of quick contacts. You can see the antenna at the end of the video. If I remember, i just hooked it up to see what it would do
rehttps://www.youtube.com/watch?v=oNEz2hSwAi8&t=90s

I will try it again, especially now that we have been having good dx conditions. I would really like to get the feedpoint up to about 20 feet, but i think it would get noticed too much by the neighbors.
 
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