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What would you do 3 acres & some antenna wire?


#41

There is some really wacky and interesting antenna designs in there !

IMO better than the ARRL antenna handbook !

Jonathan


#42

Kewl. Looking at the picture of one it looks like one antenna hole is HF/6 and the other is 2/70. I am running a 480 so I got 2 HF antenna holes. Can you make both for HF? That’ll give you 2 antennas on HF real easy.


#43

Unfortunately not, otherwise it would be very easy!

As you say, one connection is HF, the other one is VHF/UHF. As far as I’m aware there is no way to change this.

That said, I might stick a small VHF/UHF antenna on top of the mast supporting the HF antenna as there are a couple of summits near by where people occasionally come up on VHF.

I have seen several internet controlled antenna switches online which aren’t that expensive. We already have the internet connection, so probably just a case of forwarding the right ports to the right place in the 4g router.

Something to look into at a later date.

I’m working on the basis of keep it simple with one antenna to begin with and add to that at a later date. If I try to get too clever too early then things are going to start to go wrong.

I’m taking the view of start out simple. Iron out any unforeseen problems or issues that I may have overlooked first. Once I’ve proven the concept and sorted out any reliability issues then I can start to add to it.

As I said, discretion is key, so I can’t go too crazy with too many antennas. It’s probably still going to be a fairly modest setup.


#44

Sounds great. And it’s lot of fun! You’ll be doing heaps, like HEAPS, of research.

One thing you might want to check out is VirtualHere. https://www.virtualhere.com/home It’s a sweet little program that you run on almost anything and it gives you remote USB ports on your PC. I have it running on an Raspberry Pi 2 and I used it to send 192 KHz SDR I/Q, control a rotator, talk to a the Si chip in the SDR, and anything else that pops into my mind that needs a USB port.

I am also getting young fellow at work to rework his remote channel software for an Arduino so I can control my antenna switch, beverages, and flip a few other relays. All up cost buying bits and bobs on ebay will be around $AUS100,

For work we do a lot of remote sites with lockable cabinets. Just a box in a paddock, sometimes we throw in a telegraph pole. There are not expensive and they just look like well a “telegraph pole”!

Matt.


#45

Hi James,
If those bands are far enough apart - such as TOp Band and 20m or HF and 50MHz or HF and 2m then multiple antennas can be handled through a duplexer or triplexer. If the rig has multiple antenna sockets there is already a split but as a general solution, this is an unpowered automatic, set-up and forget solution.
I use such a diplexer to split the out put from my IC7300 to HF to one antenna and 6m & 4m to another (dual-band antenna).
here’s my article on this unit:

73 Ed.


#46

Hi Ed,

A very good point (a possibility that I hadn’t actually considered).

I have done this before in a mobile setup running a quad-band Yaesu FT-8900 (10m, 6m, 2m & 70cm), where I wanted to split the output to three separate antennas.

On the plus, this is an unpowered, fully automatic, relatively cheap and easy soloution. Once it’s wired up, leave & forget about it.

On the negative side, I did notice a bit of loss in output power & a slight rise in SWR. Therefore I don’t think that it’s a particularly efficient solution but it does work.

A good suggestion though.

Regards,
James.


#47

That probably needed some adjustment in component values then - was this a commercial unit or one you built yourself? The commercial versions by definition are a bit of a compromise as they are mass produced and not custom-built for your required frequencies. No power loss or increased SWR through my home built unit.

Ed.


#48

Have you looked at a G7FEK multi band antenna?


#49

Commercial unit.


#50

For what the commercial units are - a plug-in unit, they’re OK but can have some losses. If take a look at my article, building your own (if you need one in your final plans) can be relatively easy if you only want to split HF from VHF. Splitting individual VHF bands for each other (e.g. 6/4/2m) is not so easy.

73 Ed.


#51

On a 3 acre plot - surely not, what a waste of all that land! This is a compromise antenna for a small garden. I would not expect stellar performance myself from this aerial, but it would probably work OK on some bands in a small garden set against an effective ground / earth wire counterpoise.

73 Phil


#52

Not one that I’ve come across before, so I spent a bit of time reading up on it this morning.

From what I can tell from the write up, a normal dipole gives better NVIS performance (which is what I’m looking for on 80m for UK SOTA contacts).

As Phil says, a dipole or full wave loop is probably a better choice for the amount of space available.

My initial thoughts are to stick with either a dipole or full wave loop at the remote site. I can however see myself using this design at my home QTH.

I currently don’t have anything on 17m, and I would like to downscale some of the antennas at home once I get the remote site operational. I’m thinking that this could be resized to give me 20m & 17m (or maybe 20m & 40m) from my home QTH.

Thanks for the suggestion.


#53

Fair point, was thinking of multi band performance without much requirement for atu. But thinking about it, with the size of plot a fan dipole for the bands wanted would work well.


#54

Yes Steve, you could be right there depending on the lay of the cables in the fan dipole and how they react to one another. I personally would go for a coax fed off centre fed dipole cut for the 80m band (known by some as the Carolina Windom - you can get these to match at less than 2:1 SWR on 20m, 30m, 40m and 80m without any tuner with some trimming and experimentation. I tried to build a fan dipole for 20/40/80m on an inadequate plot and gave up trying to get it to match on all bands, going back to an 132 foot top doublet fed with 300 ohm window ribbon, but this was 30 years ago. The 80m OCF dipole with choke part way down the drop seems to me to be the best of the 3 between the old G5RV with ATU and a doublet fed with ribbon to an ATU. For my OCF I was advised by another “expert” who had good test equipment to use a 6:1 balun at the feedpoint if the aerial was more than 45 feet which mine is, and to use 4:1 if the feedpoint was lower than this. So I bought the 6:1 balun from the German expert at Friedrichshafen last year and put it into service. I found that I got the best match with mine which is on a pole in a tree with the 6:1 balun, a home made ferrite choke 22 feet down from the feedpoint - which the theorists say introduces a vertical component. I also found that a commercial choke balun from the same German source at the fedbox at ground level gave me a lower SWR on the main bands of interest - the aerial at around 48 feet AGL is a good performer on 30m, 40m and 80m. For 20m, 60m and 160m I use something else.

There is talk on the thread of diplexers, auto ATUs operated remotely etc. I think that lonely 20 foot tree ALSO could be pressed into service in its own right as a vertical or inverted L fed against a counterpoise. James would then have at least two 100% resonant aerials on the two main bands of interest. It may be easier and more reliable then to remotely switch between these two antennas - than to actually tune them remotely, but I know nothing about the remoting concept unlike other correspondents.

James - when is the work on the station going to start - this week, month, year or decade I wonder? It will be interesting to see which way you jump having regard to all us “amateur experts” pitching in with ideas.

Please keep us informed of progress!

73 Phil`


#55

Hi Phil,

I guess technically the answer is that the work already has started. I think the question is probably more along the lines of “when will it be on air & operational?”

The answer to that question is that I hope for it to be operational before the end of February (that is the target date that I have set myself).

At the moment I am awaiting delivery of some components (solar chargers, voltage regulator, electrical connectors etc). Some of which are coming from China, so they could take a week or two to get here.

There are a couple of other things on the shopping list that I still need to figure out and/or order:-

  • I need to sort out a mast. I have a friend who has offered me a 15 meter aluminium mast for £50. I’ve yet to have a look & see if it’s suitable (& what condition it is in) but I may have that off of him. Failing that, I will need to figure out an alternative mast arrangement.

  • Guy rope to support the mast.

  • 4G antenna for the router as the 4G signal isn’t strong enough to be reliable without external antennas (especially if the router is going to be locked in a metal cabinet for security and to keep it out of the wet weather that we seem to have a lot of in this country).

  • Lockable cabinet to put all of the equipment in.

As you can see, there is still a bit to buy/do. Unfortunately it’s not going to happen overnight.

Some of this may have to wait until my next payday towards the end of the month as money is starting to get a little tight this month.

Apart from that, it’s just a matter of finding the time to assemble the system and then get down the field to install it.

I spent some of today starting to modify the ammunition case that will house the radio, tuner (if required) and RemoteRig box. I’ve had to drill holes in it to route cables, attach the radio mounting bracket etc, then reseal it to keep as much moisture out as possible.

If I get the mast sorted, I may try to get down the field within the next week or two to get the antenna up. It’s simply a case of time, money & waiting for mail order components to arrive.

Ideas which have been very useful and highlighted a couple of things which I hadn’t originally considered.

There are a lot of very knowledgeable people on here and it couldn’t hurt to get a few ideas (hence why I asked the question).

As a result of several suggestions, I’ve dropped the idea of a long wire (which was in the original plan) and decided initially to set up the trapped dipole (which I already own) on 40/80 as a stop gap to get me on the air & test the system.

What the permanent arrangement will be remains to be seen, but I do like Ed’s suggestion of a full wave loop on 160m if I can make that work without it being too obvious.

Will do. For the reasons mentioned above, I don’t expect much to happen with it for at least a week or two.


#56

Hi james,
thanks for the plan overview. A couple of comments (there’s always a couple of comments) -

First point - good idea to go with what you have to start with to at least do basic tesing. Will that trapped dipole be supported from just the mast (i.e. Inverted-V configuration) or the classic horizontal dipole with the tree at one end a mast at the other and the coax dropping in free-air at the middle?

Second point - the aluminium mast - if you intend connecting the antenna in Inverted-V form to that as the only support you’ll need some way to locate the antenna wire away from it - even if it is in a different plain to the antenna the metal could affect the operation of the antenna. Have you consided the ex-military fibreglass mast sections, they’re solid , a dark, less obvious colour and relatively strong. They wont affect the antenna wire. Another option is the heavy duty version of the fishing (aka Squid or Crappy) poles, with pipe clamps at each junction to keep it from slipping down.

73 Ed.


#57

In a former working life I was slightly involved with large antenna towers, and planning authorities liked us to paint them duck egg blue and storm grey (one for horizontal sections the other for vertical, though I can’t remember which!) The theory was that they were mostly seen against a cloudy sky, and these colours made them stand out less. Obviously if the backdrop is hills and trees, a darker colour might be better.
Shiny aluminium might not be the best choice…

Probably a minor point, but having thought of it I might as well share :smile:


#58

Haven’t completely made up my mind yet.

Current thinking is to use a 15 meter mast in the middle, and support the ends at around 6 meters above the ground using either a tree or smaller masts (although I would prefer to avoid having too many masts if I can).

I did wonder if this was likely to be a problem.

Currently looking into that. Been looking on eBay to see if I can find one at a sensible price.

Failing that, I might just have to go with the aluminium mast as a temporary measure and see how it goes with a view to changing it as soon as possible.

Just to throw a quick question back at you regarding a full wave square loop on 160m. Would aluminium masts on each corner cause an issue in your opinion?

I wondered if there would be any coupling/de-tuning effect.

I’m taking the view that as long as the wire is insulated with dog bone insulators and a length of about 2-3 meters of guy rope should be fine.

The masts would be in a totally different plane to the antenna, although 2-3 meters is fairly negligible when you are talking about a 160m wavelength.


#59

Have you considered glass-fibre? There is an advert in Radcom every month. (other sources may be available) Wide variety of diameters available, This would be good if you plan adding a vertical wire antenna.
My home made tilting mast is made from their tubes and has stood up to pretty brisk winds with a 13 element 2m & 70cm yagi at 10m on top.
73,
Rod


#60

Hi James,
With a loop you have the advantage that the antenna wire doesn’t need to go to the support mast as you say the “corner” of the loop can be on a 2-3m cord from the top of the mast, in fact most people do that. get the masts out as far as possible anthen the loop runs inside the area within the masts but not too them. Also the loop would have less problems with the metal masts in any case as the antenna will be at 90 degrees to the mast (i.e in the horizontal, not the vertical plane). With an inverted-V dipole as a comparison, the wire is going down at an angle and hence a metal mast can have (in principal) a greater effect.

I just took a look at the UK eBay and you’re right there’s not a lot advertised there - several sellers from the US but the shipping costs would be horrific.

I don’t suppose you are planning to come over to Ham Radio in Friedrichshafen in June are you? The last three years, there’s been a guy their with ex-military F/G masts in the flea market area and by the fact that lots of people seem to buy them, I guess the prices are reasonable.

73 Ed.

UPDATE: Here’s a guy in Lincolnshire who normally sells them …