Rural Antenna Options

Submitted: Monday, Feb 13, 2012 at 09:34
ThreadID: 91833 Views:2460 Replies:6 FollowUps:9
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Hi, I work away, in sometimes very remote locations and have a telstra elite USB modem with a port for an external antenna.

I have trouble getting a good signal with just the modem (especially inside dongas) and was wondering if anyone has had good experience with a certain type in a similar situation.

I need something smaller than about a meter in packed length, and also that is easily adaptable for fittings for ease of mounting/de-mounting to dongas, trees ect.

I was thinking a 6-9dbi high gain pole, or a panel, though is it true the panel has to be facing the direction of the signal?

Your thoughts and comments are greatly welcomed.
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Reply By: Nomadic Navara - Monday, Feb 13, 2012 at 10:24

Monday, Feb 13, 2012 at 10:24
"I was thinking a 6-9dbi high gain pole, or a panel, though is it true the panel has to be facing the direction of the signal?"

A panel or a yagi antenna are are directional and need to be pointed at the phone cell to get best transmission. Get a vertical stick type that is ground plane independent, that way you don't have to mount it on a metal panel. (I think most don't require aground plane but check before purchasing,)
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Follow Up By: Mike GU - Monday, Feb 13, 2012 at 10:30

Monday, Feb 13, 2012 at 10:30
Thanks Peter I'll look into it.

Out of interest could you please explain "Ground Plane Independent" for me please?
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Follow Up By: Nomadic Navara - Monday, Feb 13, 2012 at 11:01

Monday, Feb 13, 2012 at 11:01
Have a look at this page -Site Link The 4th picture down is a whip antenna that needs to be mounted on a reasonable flat piece of metal (eg roof of your car.) The flat piece of metal is the ground plane.

Now look at the top picture. These are the type that are commonly be mounted on bull-bars. They don' need to be mounted on a ground plane - hence they are ground plane independent.

If you are going to use one of these (commonly referred to as broom-stick antennas) in a portable application be careful of the cable coming out of the bottom. Standing the antenna on its bottom end can wreck the cable and it is not easily replaced. Probably safest to mount the antenna on a small plastic box and have the cable come out of the side of the box.
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Follow Up By: Mike GU - Monday, Feb 13, 2012 at 11:08

Monday, Feb 13, 2012 at 11:08
Yes of course... I understand now, well thank you for your help Peter it is much appreciated, do you have a opinion on dbi? I have to say mostly I work in flattish areas, would something around 6.5dbi suffice?

Cheers mate
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Follow Up By: Member - nick b - Tuesday, Feb 14, 2012 at 21:52

Tuesday, Feb 14, 2012 at 21:52
You can get a 16 db home base antenna ..looks like an old inside tv antenna ..
high db is ok for flat ground !!!!
Cheers Nick b
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Reply By: The Bantam - Monday, Feb 13, 2012 at 11:27

Monday, Feb 13, 2012 at 11:27
I recon you would be hard pressed to find a mobil phone aerial that was not ground independent.....does not depend on a flat metal ground plane for its operation.

on thing you need to be very aware of is that mobile phones and wireless internet run on microwave or near microwave frequencies and that means.

the transmission is very much straight line, line of sight to the tower.

cable (and other) losses are significant

lots of the mobile phone aerials come with very very thin coax cables for convienience of install......these must be kept short.

remember most dongas are made of metal clad fridge pannel and are pretty much faraday cages......if you are worried about, induced electric fields, cosmic rays, man made radiation causing cancer or aliens reading your mind from outer space.....live in a donga........they work better than an alfoil beenie...true.

get any aerial outside that donga and you will be better off..unless of course there is a window facing the right way.

there are heaps of options..how well any of them will work will depend on the situation.

Do you, can you get the same donga each trip?

one issue is how you will cable it out of the donga and how to mount it.

With some luck you might get a window facing in a suitable direction.

you could use an on glass, thru glass like is often used on cars, and buy a supply of replacement adhesive pads.

I'm not over confident on some of those because I recon most of the gain in the stick will be lost in the thru glass and the spindly little coax.....but if it gets you out of the donga and line of sight it will be an improvement.

if you can drill a hole or find a crack..you might be able to use some sort of magnet mount...unless they used aluminium for the fridge pannel.

one thing I have heard off is getting either a blue tooth or wireless ethernet access point type modem and putting that outside on a battery and connecting wireless.......if wireless ethernet, that could be placed hundreds of meters away.......ya just have to worry about someone nicking it....or cracking the security.

the first thing you need to find out is, where the telstra tower is relative to where you are working, and what the scale of the problem is.

cheers
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Follow Up By: Mike GU - Monday, Feb 13, 2012 at 19:34

Monday, Feb 13, 2012 at 19:34
"Do you, can you get the same donga each trip? "

Unfortunately Bantam we are in another part of Australia sometimes as often as every 2 months, mounting shouldn't be a problem, and as you say getting out of the donga is going to provide the biggest gain.

There is always a crack or flyscreen i can poke a cable through.

Because of the swift movement of our crew I sometimes dont have a exact location of our rig... let alone the surrounding towers.
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Reply By: guy007 - Monday, Feb 13, 2012 at 12:41

Monday, Feb 13, 2012 at 12:41
Hi Mike

Site Link

Try this site. We use their Omni non directional antenna on our caravan and have had good results. We have no other connections with the sellers.

Guy
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Reply By: Member - Joe n Mel n kids (FNQ - Monday, Feb 13, 2012 at 13:54

Monday, Feb 13, 2012 at 13:54
just go the USB extended cable, i got one about 4M long and hang it in the window, inside still, and my signal went from 1 bar and dropping out to 4 bars and constant, just draped over the curtain, you also will find you can move it around the room and it makes a hugh differance .... in the car when travelling we drape it over the sunvisor still inside the car and it jumps up by 2 bars and it saves it being knocked off or bumped...
Joe
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Follow Up By: Mike GU - Monday, Feb 13, 2012 at 19:43

Monday, Feb 13, 2012 at 19:43
Thanks Joe,

I have actually just ordered a 5m cable, just because it is only costing $6.

One thing I am afraid of is the really remote locations where I need to mount it high, to even catch a signal, usually in these locations there is no one for hundreds of km so thievery shouldn't be an issue, if in doubt I can always fix some thin wire rope to it and follow the cable to deter opportunists.

Though I did look at the site in the above link and was quoted $300 for a panel (and kit to suit) and I reckon there must be cheaper options out there for similar results.

I have googled how to get more service from USB modems, and fixing it (along with an extension) inside a sieve as if to create makeshift dish seems to work! :)
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Reply By: Member - bungarra (WA) - Monday, Feb 13, 2012 at 17:27

Monday, Feb 13, 2012 at 17:27
Hi Mike

I live remotely and travel remotely and use the Telstra Elite USB modem...also the Bigpond Ultimate USB

Whilst I concur with the others on a broomstick magnetic base antannae there are some limitations as these are not dedicated to the next G frequencis and so do not maximise the potential of getting a strong signal from some distance

I built one of these as it is very cheap,...see the link below..... very portable and very small. I have done some small modifications to it which I will detail further if you wish..and pics if need be.

http://www.tigereye.net.au/vk4ion/nextg_yagi.html

I have taken my signal from -90 at home (an average signal but at times unstable) to -50 ( -40 is almost too much by the way...so -50 is very very good...and -120 is basically not usable) and now I get a rock solid stable internet and have achieved good results up to 90km away on flat ground.

Yes you need to direction this Yagi to the tower but that is simple and quick ...can explain further how to if need be as well.

By the way my modem was purchased in Nov 2011 and after looking at all my problems (antannae was one of these) I discovered that the firmware in that modem was supplied with Oct 2010 !..obviously when it was made...I have since updated that as well and all very sweet, stable and acheiving distance
cheers

Graeme
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Follow Up By: Mike GU - Monday, Feb 13, 2012 at 20:01

Monday, Feb 13, 2012 at 20:01
Hi Graeme, I have considered making a yagi and am very interested in your experience with gaining the best signal given the location.

Is this one of the best low loss options you think?

I also would like to know of the modifications you have made.

I'll sent through my email.

Thanks Graeme.

PM sent
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Follow Up By: Mike GU - Monday, Feb 13, 2012 at 20:06

Monday, Feb 13, 2012 at 20:06
Well maybe you will have to send me an email, as I am not an exploroz member yet and cant access this option... :(
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Follow Up By: Member - bungarra (WA) - Monday, Feb 13, 2012 at 22:56

Monday, Feb 13, 2012 at 22:56
you didnt send an email address and besides it is best posted on here for others to benefit as well. The modifications were only minor just what I thought were a better method and choice of materials in a couple of spots

1. Firstly I worked in all black poly including the joiner.
2. I made the section from the joiner forward first by screwing the joiner on the end of the forward section and drilled the hole in the center of the joiner so as all the elements were in place except the reflector and the driven element
3. Then I made the driven element


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4. After I made and installed the driven element then I screwed in a short 150mm threaded short carefully so as it butted up against the deriven element and wiring
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5. Then I measured wher the reflector element hole hade to be drilled and drilled it. That way the distances were all exact
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By using all black poly it is a lot more rigid. By using the short threaded piece from the joiner to the reflector and on behind you can set the yagi to horizontal or vertical setting very easily. One end of the 150mm short is in the joiner and the other end into an elbow or T piece on your support tower.

Some towers are vertical and some are slant and therefore you may need to change the yagi to or the other. I also just plugged the far end with silicon.

All common sense really and it is as light as a feather and very strong and works a treat.

Full credit to the original design..I just tweaked the construction method a little



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Reply By: The Bantam - Tuesday, Feb 14, 2012 at 14:41

Tuesday, Feb 14, 2012 at 14:41
If you are looking at building something....up at UHF and beyond the yagi starts to have some issues and becomes less advantageous.

The biggest problem with yagi's is that they will work reasonably well below the design frequency but their gain drops off very badly above the design frequency as the directors become too large for the frequency and be come blockers.


If you want to build something with gain and some directivity, a simple bow tie & corner reflector is very simple and can be made very compact and will have better bandwidth ( quite wide bandwidth) especially above the design frequency.

the other similar item is the bow tie & cake rack, like is very common on UHF TV......for example the WISSI EE06........4 bow tie or wisker driven eliments mounted in front of a flat grid..gives about 10ish db gain compared to a dipole.

If ya doing a yagi..think about using a folded dipole driven eliment, because a standard 6:1 ballun will get you a match on 50ohm coax

the bow tie can be manipulated to a certain extent to match up.

There are a heap of off the shelf next G aerials on the market..so y'd have to be either keen of have the ability to very easily build to bother.

As I said earlier....it might just be cheaper to buy a nextG wireless ethernet access point and put that somewhere suitable.

there are even some that ya just plug almost any wireless broadband card, usb or modem into and you are away.

cheers
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