Hypothetical here, but you are camping and have a view that overlooks a city. 1 to 7 watts tx drawing power from a small camping power pack inverter perhaps a small solar panel. But just assume it's just fully charged without, and the transmitter is just playing prerecords. Would the hill block signal from behind making it sort of directional which is the goal here? What issues do you see, one might get? Excluding nosey gits.. with a big enough tent this could just all sit inside.

Forgive my rudimentary picture, and yes would have to find a dug in for tent to not be on a slope.

The idea would be the pole to be just over sized to incorporate size of frequency lengths of the dipole.

Mongo82 wrote: ↑Sun Jun 29, 2025 10:48 amWould the hill block signal from behind making it sort of directional which is the goal here? What issues do you see, one might get?

Yes, but closer to the top of the hill you will get some signal going over the top. Coverage with respect to terrain is largely predictable but there are usually odd things that you can't easily explain. This isn't really an issue as such but I'd consider a directional antenna so as not to waste power warming up the top of the hill.

Apart from that, the only issue I can think of is the height of your dipole above ground, dipoles are quite forgiving in this area compared to e.g. a Yagi, but I'd say you want your antenna at least a wavelength above the ground.

I agree with Shuffy, you will essentially be wasting roughly 180 degrees of your signal into the dirt of the hill. Particularly if you are not quite at the top.

The best solution would be to put the aerial in a nearby tree to get necessary elevation from the ground. Also if you add a reflector (or director) you can increase the erp by a large amount. Just adding that one piece of metal behind (or infront if using director) can give you 4-5dbd of gain. That way not much power is wasted behind into the hill.

There is some really good info here on how to do it...

https://www.hamuniverse.com/wb2vuo2elyagi.html

Cheers will take a gander at that. I've been spending a couple of hours dry testing a flower pot antenna, it really is hit and miss, even with the correct winds and lengths of the coaxial cable inside. I'm wondering if it would be better just to tape the cable to the outside of pole?

Anyway got a swr of 1.8 around 99.8 slightly adjust of the coil gave me in the region of 105 and 106 at 1.5 and 1.3... couldn't get 1.1... That's if I am reading that right?

King Croccy wrote: ↑Sun Jun 29, 2025 5:00 pm I agree with Shuffy, you will essentially be wasting roughly 180 degrees of your signal into the dirt of the hill. Particularly if you are not quite at the top.

The best solution would be to put the aerial in a nearby tree to get necessary elevation from the ground. Also if you add a reflector (or director) you can increase the erp by a large amount. Just adding that one piece of metal behind (or infront if using director) can give you 4-5dbd of gain. That way not much power is wasted behind into the hill.

There is some really good info here on how to do it...

https://www.hamuniverse.com/wb2vuo2elyagi.html

If you place the dipole on a metal mast and use that as the reflector instead of adding an element whould be less to take and easier to do.

Is that adding a mast and bringing in line as high as the positive element?

I guess there will be a very good signal there everywhere pictured, likely blending to mono with the buildings effecting the signal, if the area was open countryside I suspect there would be no problem.

You also have the radio shadow effect, the aerial would have to be on the very near to the edge, buildings at the bottom of the hill or close to it will likely get reduced signal. I guess a compromise would have to be made as you wouldn’t want your tent on the edge or a tall mast with the aerial on top.

I used to have this problem, it was hard to get an unbroken stereo signal at a mile distance with low power, I built this weird end fed aerial, pretty much the only time I had an unbroken signal.

Mongo82 wrote: ↑Sun Jun 29, 2025 7:03 pm Cheers will take a gander at that. I've been spending a couple of hours dry testing a flower pot antenna, it really is hit and miss, even with the correct winds and lengths of the coaxial cable inside. I'm wondering if it would be better just to tape the cable to the outside of pole?

Anyway got a swr of 1.8 around 99.8 slightly adjust of the coil gave me in the region of 105 and 106 at 1.5 and 1.3... couldn't get 1.1... That's if I am reading that right?

I’ve always used alittle handheld scanner with the aerial unscrewed afeet away to tweak up an aerial, usually lower the power down, if it had a 1w setting you'd put it on that. I suppose an aerial can be correct with all the formula’s but the swr can show high, likely effected by objects around it, so it may still be working. If you’ve got a tuneable output stage can change the capacitance can make an awful lot of difference, if the mw's aren't going to the antenna can lead to heating of the output device. I put my hand on mine after abit, if its luke warm I know its tuned, I suppose probably not the way others do it, I suppose there might be some way to test the temperature though and check that it is happy.

radionortheast wrote: ↑Mon Jun 30, 2025 8:55 am I guess there will be a very good signal there

It's about 110m above sea level. The image is just ai as an example.

It was mentioned a mast being used as reflector, the way described does that mean the dipole would look like an H ((((

Mongo82 wrote: ↑Sun Jun 29, 2025 9:45 pm Is that adding a mast and bringing in line as high as the positive element?

Its a good point from gigahertz, I've never done it this way personally but I'd assume (from previously building a dedicated 2 beam dipole reflector), you would make the mast a bit longer than the top element. On a dedicated reflector antenna the back element is usually 5% longer than the overall span of the dipole. I'm guessing if you have a continuous mast, you would need to make the mast poke 2.5% above the top dipole element?

Mongo82 wrote: ↑Sun Jun 29, 2025 7:03 pm Cheers will take a gander at that. I've been spending a couple of hours dry testing a flower pot antenna, it really is hit and miss, even with the correct winds and lengths of the coaxial cable inside. I'm wondering if it would be better just to tape the cable to the outside of pole?

Anyway got a swr of 1.8 around 99.8 slightly adjust of the coil gave me in the region of 105 and 106 at 1.5 and 1.3... couldn't get 1.1... That's if I am reading that right?

The flowerpot is a great antenna and so easy to make. I just tape the coax on the outside when tuning and then put it inside the pole when resonant. Ive got mine down to very low readings (well below 1.10 - 1). My advice (if you are using a online calculator), ignore what length they give for the top element. Make it 10cm longer, often they are miles out. Start cutting from there for lowest reading.

I wouldn't say I've quite perfected the antenna yet. Had a few problems, the first prototypes had "swr bounce" particularly in high winds. One even blew up a very conservatively running mosfet that can do a lot more power than we were running. Problem appears to be the coax is loose inside the tube. Ive tried squirting silicon blobs inside the tube and this sort of helped but made the analyser swr line look a bit "jagged" throughout the sweep of frequencies. As the weather is nice, might try expanding foam next see if that is any better.

The only other issue is the balun, where it is coiled up gets really hot and can start melting the pvc conduit! I've managed to run 200w with no issues but 300w is too much for the cable/conduit I'm using (RG8X). I will be coming back to this antenna soon got a few ideas how to improve it lol

[quote="King Croccy"
Ive tried squirting silicon blobs inside the tube and this sort of helped but made the analyser swr line look a bit "jagged" throughout the sweep of frequencies. As the weather is nice, might try expanding foam next see if that is any better.
[/quote]

Expanding foam sounds like an idea or perhaps stuffing inside pipe insulation to hold the coax in place. Not sure how it would effect the output, but its already incased in pvc plastic.

What about a Moxon antenna?
It is a bit tricky to build and tune, but has a good front-to-back ratio in the radiation pattern (according to web sources)

I have done back in the day couple "flowerpot" antennas, 8mm hydraulic pipe, insert RG58 trough it and crimp it shield to the tube with hydraulic connector crimper and one of these hoseferrules. Then just suitable piece of plastic to the lathe, run it so it fits nicely top of the hydraulic tube and holds stainless steel rod straight up. Use one of these small thick ferrules to hold it in the center pin of coax. Cover all joints with good epoxy and heatshrink to protect it from UV radiation.

I used choke+ferrite at the end. Works and lasts years up on the sky.

Krakatoa wrote: ↑Mon Jun 30, 2025 8:08 pm What about a Moxon antenna?
It is a bit tricky to build and tune, but has a good front-to-back ratio in the radiation pattern (according to web sources)

I've always found those antennas to be massively finicky, whether it's the spacing between the ends of the two elements, or the dimensions and have pretty narrow bandwidth (fine if you're on a fixed frequency). I also found that they are quite sensitive to being put next to anything else, such as a building, tree, piece of wood, dead pigeon, etc.

The DK7ZB antennas are quite easy to copy as they match directly to 50 Ohms, have 4dB gain and have very short booms so all that is needed is a coax choke to feed them.

Mongo82 wrote: ↑Sun Jun 29, 2025 9:45 pm Is that adding a mast and bringing in line as high as the positive element?

That was going to be my suggestion too! If you get the boom length just right (it's worth making it adjustable for best match), you can get around 4 dB of gain. If your rig is developing 6 Watts, if your aerial is optimised (remember that the reflector is slightly longer than the dipole, and the impedance could change) you will get 11 - 12 Watts erp. The radiation pattern will be (essentially) hemispherical.

It mighht seem peculiar, but altering the boom length (ie: the distance between the dipole and the reflector) will affect the feedpoint impedance. My old "improvised" 2- element Yagis used a folded dipole as the radiating element, and a balun (actually a un-bal) to convert the unbalanced 50Ω rig output to the balanced feed needed by the folded dipole.....

If you can get the aerial up a tree, for more elevation, so much the better. My earliest Californian installation used two stacked 2-element Yagis with balun feeders and a homebrew phasing harness up a big tree up a hill. With my paltry 45 Watts into it, we got reasonable mono coverage over much of the city below - and got enough attention from the FCC that we "lost" the first install after a couple of weeks!