HF Antenna help please

[VK7ZA]

Hi All,

I'm starting to play with HF, and would like to work out my best antenna options. I would like to be able to work DX, in addition to more local. First the site details.


Map at http://binged.it/1GJ60Az

• Site is about 30KM south of Hobart.
• I've added the lengths of each fence and building side in meters.
• Wooden fence is 1.8m high on all boundaries except 56M edge where there is no fence.
• The house is 7m high, with a south sloping skilleon roof of about 5deg pitch.
• The shed is a regular pitched roof, 3m at base, and 8m at top of pitch.
• Both roofs are clad in colourbond.
• House is clad with brick on bottom and cement sheet on top. Silver paper in walls on both levels.
• Shed is clad with cement sheet.
• I would need a permit for anything above 8m.
• A tower won't get *domestic* planning permission, so needs to be unobtrusive.

I had hoped to put a HF beam as well as long wires on the roof, but after realising that I only have 1m height to play with it looks like that option is shot short of applying for planning permission. I imagine that the colourbond roof will muck things up with running most horizontal antennas one to two meters above roof height.

I strung a dipole(about 30m) along the north fence over the weekend, and was receiving UK and Germany on 20m at S9, but wasn't heard when trying to TX. I assume more height would be preferable.

Anyway, for the guru's out there. What would you do given my situation? Any suggestions or guidance would be greatly appreciated.

Lance.

[VK3ALB]

Hi Lance,

You didn't say where the shack is and if you can't put up any supports you're kind of snookered. It's kind of like how long is a piece of string. Whatever you choose someone will tell you that there is something better available.

Firstly, I would recommend against buying an antenna. Wire and aluminium is not that expensive and can normally be scrounged for even less. Insulators can be made out of cutting boards and there's plenty of info regarding building wire antennas on the Internet.

Consider a single band vertical supported by a squid pole - search for VK7JJ. Consider a simple dipole on your band of choice but you need to get more than 6 feet in the air. The other option that you might consider is a magnetic loop - generally single band and within reason can be installed close to the ground.

I would do the following: I assume the shack is either in the shed or the house so make a wooden mast (as tall as permitted) and install it on the south fence. Put a support at each end of the south fence (say 3m high) to keep the ends of the dipole out of the reach of humans. If that is unacceptable to the minister for war and finance then do the same at the north fence.

Add pulleys and ropes to each support so you can raise antennas easily. You will have plenty of space to build an inverted V for 80m with this arrangement. You might even consider a trapped multi-band dipole. Once you've started there will be room for improvement and experimentation.

Good luck

[VK4GJW]

Hi Lance,

What Lou VK3ALB said is good info. I live in rental accommodation and my block is even smaller. The backyard (if you can call it that) is only 15M across. What I mounted on a 9M aluminium pole was an inverted V for 40M. Just fits in the block, with the ends about 2.5M above ground. Another antenna to consider that I am still looking at trying later in the year is a Cobwebb antenna. Good for 40, 20, 15 and 10 and takes up very little space. Have a look on Google, there are lots of references to it. Other than that, as they all say, ANYTHING you can get up, is better than what is in your head! For ages I just ran my 40M dipole on top of the fence. Not ideal by any stretch of the imagination, but from SE VK4 I got into VK2, VK3, VK5 and even ZL occasionally! Just get SOMETHING up, as they all kept telling me!

[VK4WDM]

I have a very small block here with an 8m height limit. I have a lightweight aluminum mast hinged at the bottom. It has my 6m, 2m and 70cm yagis on it.

For HF I am using an 40-6m Off Centre-Fed dipole mounted on the above mast below the VHF/UHF antennas so at its centre its about 6.6m and 5m at each end. I have been surprised at just how well it works on all bands with an outboard tuner.

Your other option would be to do as my old Elmer once told me: "put up a wire inverted Vee as high as you can, and as long as you can, and fed it with open wire line (easy to make) and a balanced coupler." (easily built)

I also have a commercially-produced multi-band vertical, the Butternut HF9V which also works well but needed a lot of work to install 26 radials.

Don't try for perfection initially, just get some wire in the air, have fun, and improve the setup as you go along, but remember there is the danger of becoming a TAWAN, an affliction for which there is no cure

73

Wayne VK4WDM

[VK3MEG]

Lou has hit it on the head a few things to add though.
8m height is fine i worked well over 100 countries with my trusty g5rv at 6-8m high these are a good antenna. also I have a 40m delta loop with an 80m element. (i have worked about 60 countries on on 40m with this and 100w). this is fed with 75 ohm coax and performs well on 80m through to 6m at a pinch. The beauty of it is it doesnt have a 300 ohm feed which dislikes metal like the g5rv. i have mounted my Loop with 2 tv antenna hocky sticks with extensions( 6-7m total height) at each end of the house. then I have a a pole on tthe other side of the house in the midle about 8-10 m height for the top this gives the antenna some vertical polarization and helps with the dx. the 20m long 80m/30m element runs off and is not straight and is 5-6m off the ground above my shed. this antenna does require a tuner for bands other than 40m but works pretty good. btw a yagi on an 8m tower is better than no yagi at all. my 10m yagi started @ 5m and was still pretty good and was way better than wire. i even worked antartica on 15m using a tuner.also a multi band vertcal on the shed roof would work well. pictures of my antenna's on my qrz page
Dx is worked with persistance,determination and lots of listening more Than what type of antenna you have. antennas help but with out the former its will still be a struggle i have a few friends who only use wire and they work plenty of dx just they might not use ssb as often.

btw I think your site will be great for radio. Talk to you neighbours and mention your hobby. That for me has been the best thing i have done now they dont fear me an dont question why i'm up a ladder or on the roof they know I'm chasing a better signal not trying to looking to their back yard.

catch you in the pile ups
cheers

a pic of my delta loop

[VK7ZA]

Thanks for all the responses. Certainly lots to mull over.

For those that asked, I don't have a permanent shack setup yet. There is a loft space in the top of the shed, which I would like to use.

Someone mentioned putting an antenna at the back of the house (south). As there is only 3m between the house and fence, if I put it right at the south property boundary, how will that be effected having the house in the way of north (where I expect most contacts to be)?

Looks like an inverted V it is to start with. I'll keep you all posted.

[VK3ALB]

Someone mentioned putting an antenna at the back of the house (south). As there is only 3m between the house and fence, if I put it right at the south property boundary, how will that be effected having the house in the way of north (where I expect most contacts to be)?

Hi Lance,

Yes there will be some effect but as yet I haven't found a way to easily model the effects of sheds against antennas.

I operate a dipole at 7m that is only 3m from the end of a 10m x 10m shed that is 6m high at the apex. No doubt there is a impact on the operation of the antenna but I still talk into EU on 20m and 15m when the band is open. The way I see it, if I want to get on the air I just need to fit the antenna where I can and deal with the results. You could always set your antenna up on the north fence but then you have to figure out how the feedline will get back to the shack.

There are compromises to be made everywhere.

[VK4TI]

Looking at the yard I would suggest several option , you have lots of roof and ground-plane so maybe a 43ft vertical with a base mounted tuner (or a 33.5 ft for 40m and a tuner ) , that will tune most of the bands across hf , you might raise a pole and drive a 43 ft wire through a 9:1 balun off some coax . A dipole if it gets close to fitting and bend it some on the ends maybe or perhaps a small tribander or mono for a band you like at the legal height of 10 meters . then some 6m and 2m considerations and you have mostly what we all start with
Good luck and enjoy

[VK2MUS]

I use a MFJ mag-loop covering 10M to 30M I mount it horizontal about 1 meter off a tin roof - My contacts range right around the world . I also use a mfj 1793 Multi band Vertical covering 80m thro to 2m this is a top loading antenna and when on the pole sits about 20feet above ground (total height approx 37 feet) at the moment it is sitting on the ground against a fence waiting for repairs from bird strike and still brings in signals from around the globe. True these antennas do cost money but once you have them they will last you years and give you excellent coverage across a wide spread of bands.

The other solution is to build a cobweb - you do not need any great height , it does not worry about buildings etc and is easy to build . One last alternative is to place a tilt tower in a trailer - this is then out of councils control as it is not placed on the ground and as long as you don't try to drive it anywhere it is outside RTA control. North and south etc is not a major concern - with DX you are shooting at an angle upwards to the F Layer so as long as your signal is not blocked by a mutl-floor sky scraper you should be ok

John