Antenna opinions and suggestions (started with Tak-tenna)

[VK2FABS]

Hi all. Just received my F license and keen to explore what I can do on the HF side of things. Being restrained by space/strata in the inner West of Sydney, I've been looking at the various compact antenna options. Then I came across this Tak-tenna.
http://www.tak-tenna.com/

Did a search here but didn't come up with any posts on this antenna design. Does anyone have any experiences with this? Anything thoughts on this antenna design? I was quite impressed by its ability to cover multiple HF bands. Otherwise I've considered the magnetic loop antenna but it doesn't look to be too convenient with its need to retune at every frequency. Also looked at multi-band dipole but for the 10m or so of roof space I have, it's not going to reach 40m for a 1/2 wave dipole. I am lucky though that my roof space is aligned to the NE and am at the top floor with unobstructed access to the north and to the Blue Mtns to the West. A hill covers the south side.

Anyway, interested in your thoughts. Thanks.

[VK3YE]

Otherwise I've considered the magnetic loop antenna but it doesn't look to be too convenient with its need to retune at every frequency.

There is always a compromise with small antennas. You can have two of the below but never three.

* Wide bandwidth
* Good performance
* Small size

Assuming the antenna has to be very small you are going to have to tolerate narrow bandwidth for good performance. Fortunately people have come up with ingenious remote tuning schemes so it isn't too much of a problem in practice. A very small antenna with a wide bandwidth is bound to be inefficient.

Also looked at multi-band dipole but for the 10m or so of roof space I have, it's not going to reach 40m for a 1/2 wave dipole.

This might actually be your best option. Dipoles do not have to be straight and you can bend their ends around a bit. 10m is 50% down on a full size. Half size wire antennas can still produce usable results that are probably better than very small antennas. They are also a lot cheaper.

* You can make an antenna smaller with loading coils on the end. http://users.picknowl.com.au/~wavetel/antennas.htm contains info on a multiband dipole that is small (see the HF 4 bander). A & B is an element that works on both 80 & 40m. It fits in a 20m space. If you do half dimensions you'll have a 7 & 14 MHz dipole that will fit into a 10m space.

* A half sized G5RV is 15m long. A wire in a 10m space with 2.5m bent around on the ends might fit. It will need an antenna coupler to make it operate properly but these are easy to build.

* The antenna at https://www.youtube.com/watch?v=cfh7LcLDqH4 is a centre loaded vertical that covers 7 MHz. It's 5m long. Making two could form a dipole for that band. Again it could fit into a 10m space.

* https://www.youtube.com/watch?v=TV3Cj2J3T20 is an end-fed antenna for 7, 14 & 28 MHz for portable use. It is 12m long. It could potentially be used in a roofspace.

[VK2FABS]

Thank you Peter for the detailed comment.

The multiband dipole I've come across was shown on the page below. Looked very neat in a roof space.
http://www.qsl.net/hb9mtn/hb9mtn_40-10m_dipole.html

Your suggestion of end loading coils is interesting. I'll need to read up a little more on that as my current knowledge is still a little limited on coils and antenna designs in general. I liked the idea of that tri-band 12m mobile solution. Didn't look too complex and it may come in handy for use on bushwalks. Didn't quite understand and the importance of the different gauges of wires used for the two sections. What's the theory on that?

[VK2MUS]

The magnetic loop is ideal for restricted space however as you point out it has to be re-tuned with change of Freq. I use mine for jt65/jt9 work so retuning is not a problem - if you have a flat roof then it is worth looking at a cobweb antenna easy to make and will cover the Foundation Freq allowances and above. Does not need ground radials does not need great height and is fairly immune to surrounding buildings. The MFJ1798 top loading vertical antenna will cover all the bands you need plus 2m and does not need ground radials nor any height (will work at about 6 foot off the ground) to work right - in fact you can lay it on its side in the roof and it will still work ok.

The Tak-Tenna just sounds a bit too good to be true - it is basically a half wave dipole reading most reviews it appears that the longer the feed line then better it works!
however if you wish to try one then they are easy to build see
http://billbrwn.tripod.com/id3.html

john

[VK3YE]

Thank you Peter for the detailed comment.

The multiband dipole I've come across was shown on the page below. Looked very neat in a roof space.
http://www.qsl.net/hb9mtn/hb9mtn_40-10m_dipole.html

That should work well but with so many wires/bands will be a pain to set up. I suggest starting with one band (eg 40m), getting that right, then adding more wires later.

Your suggestion of end loading coils is interesting. I'll need to read up a little more on that as my current knowledge is still a little limited on coils and antenna designs in general. I liked the idea of that tri-band 12m mobile solution. Didn't look too complex and it may come in handy for use on bushwalks. Didn't quite understand and the importance of the different gauges of wires used for the two sections. What's the theory on that?

Wire gauge doesn't matter very much. Any antenna with a loading coil will require a fair amount of cut and try, especially if it's for multiple bands.

[VK4WDM]

Experimenting with antennas is, IMO, one of the really interesting aspects of AR. My suggestion is to go for something very simple and once you have got that working, build something more complex. As Peter says. "fan" dipoles do work but they are a right pain to tune because all the wires interact, prune one and the rest change - can drive you

My suggestion would be a vertical wire strapped to a squid pole using your roof as a ground plane or mounted on the lawn with about 6 radials. You will need an antenna tuner but they can easily be built. Have a look on Peter VK3YE's web page for ideas on antennas and tuners. Ideal for portable ops too

For more complex you could build either a half-wave horizontal loop - a triangular shape works well at low height, or as somebody else said, a half-size G5RV. To fit it in a small space you can twist the ends around or mount each leg at the halfway point and let the rest hang down - a sort of "tent shape."

Importantly, remember that the any antenna you have in the air is going to give you some contacts whereas the one stuck inside you head won't.

Also be aware that playing with bits of wire can be very addictive and there is a danger of becoming a TAWAN, a terrible affliction for which there is no cure - just ask my XYL

73

Wayne VK4WDM

[VK2FABS]

The magnetic loop is ideal for restricted space however as you point out it has to be re-tuned with change of Freq... if you have a flat roof then it is worth looking at a cobweb antenna easy to make and will cover the Foundation Freq allowances and above. The MFJ1798 top loading vertical antenna will cover all the bands... in fact you can lay it on its side in the roof and it will still work ok.

The Tak-Tenna just sounds a bit too good to be true - it is basically a half wave dipole reading most reviews it appears that the longer the feed line then better it works!
however if you wish to try one then they are easy to build see
http://billbrwn.tripod.com/id3.html

Ummm... Haven't read about the feed line radiation as a basis for performance. Definitely more reading needed. I note also that Bill's homebrew Tak-tenna looked pretty rough. The circular loops were all crooked. I wondered if circularity of the wires affects the ultimate performance? A point for experimentation I guess. As for the cob-web antenna, I am afraid that my available space won't allow me to make one that'll reach the HF bands. Limitation of strata living.

That should work well but with so many wires/bands will be a pain to set up. I suggest starting with one band (eg 40m), getting that right, then adding more wires later.

Wire gauge doesn't matter very much. Any antenna with a loading coil will require a fair amount of cut and try, especially if it's for multiple bands.

Thanks and a most wise consideration, to start on one band first. The more I read into all the options the more I think I'll need to gear up on SWR meter, tuner and various other test gears. I think I'll need to start a separate thread to seek advice on bench gears, including a transceiver. Initially I thought the antenna will be the biggest challenge and I think I've underestimated the planning.

Experimenting with antennas is, IMO, one of the really interesting aspects of AR. My suggestion is to go for something very simple and once you have got that working, build something more complex.

Yes, antenna will certainly be a major component of the experimentation and I have no fear apart from the available space. As is, vertical HF and horizontal loop antenna setups unfortunately will not work for my situation. Don't want to induce any controversy within the neighbourhood, let alone being a scapegoat for all the TV problems neighbours may have. Thanks to you and Peter's advice on the tuning complexity of a fan dipole setup. Wasn't aware of that and guess that's the naivety of a noob.

Did a walk in Jaycar today and got familiar with all the components that are available. Promising!

[VK3YE]

Ummm... Haven't read about the feed line radiation as a basis for performance. Definitely more reading needed.

There are some legitimate cases where changing the connections to an antenna can make the whole thing including the feedline radiate. Eg shorting the feedline of a horizontal antenna to operate it as a top loaded vertical against ground. That's commonly used to get a 3.5 MHz dipole to work on 1.8 MHz.

But in other cases a radiating feedline is used to cover up an ineffective, small and often overpriced commercial product. Results might have been similar if you'd removed the 'antenna' and substituted an old metal teapot, toilet ball float, bicycle wheel or similar. Other tricks used include mystery 'matching units', baluns or even resistor arrays that claim to offer broadband performance. An example of such an 'antenna' and proof that it 'works' is in this video:

https://www.youtube.com/watch?v=46coth1Z9rQ

I note also that Bill's homebrew Tak-tenna looked pretty rough. The circular loops were all crooked. I wondered if circularity of the wires affects the ultimate performance?

How bad an antenna looks has little bearing on performance provided it's electrically OK. Slight crookedness in loops would make no difference. It could probably even be square with little change. The reverse is also true; some antennas appear well built but perform poorly - eg http://www.eham.net/reviews/detail/1533

[VK2FABS]

But in other cases a radiating feedline is used to cover up an ineffective, small and often overpriced commercial product.

Ummm... Wouldn't that make the buyer wanting to puke? I sense landmines abundant in the AR marketplace. Ouch!

[VK4TI]

Hi all. Just received my F license and keen to explore what I can do on the HF side of things. Being restrained by space/strata in the inner West of Sydney, I've been looking at the various compact antenna options. Then I came across this Tak-tenna.
http://www.tak-tenna.com/

Did a search here but didn't come up with any posts on this antenna design. Does anyone have any experiences with this? Anything thoughts on this antenna design? I was quite impressed by its ability to cover multiple HF bands. Otherwise I've considered the magnetic loop antenna but it doesn't look to be too convenient with its need to retune at every frequency. Also looked at multi-band dipole but for the 10m or so of roof space I have, it's not going to reach 40m for a 1/2 wave dipole. I am lucky though that my roof space is aligned to the NE and am at the top floor with unobstructed access to the north and to the Blue Mtns to the West. A hill covers the south side.

Anyway, interested in your thoughts. Thanks.

Sounds like a bind , however if you have roof space or can get above it then a simple fan dipole or loop will provide surprising performance , a mag loop is a great antenna if built well and with care in small spaces as an alternative , I refer you to http://www.vk4amz.com when you have time for a good read , also when your feeling comfortable have a read https://sites.google.com/site/lofturj/t ... op-antenna , I have used this material with a suitable Arduino controller via a stepper motor and driver board , a home made directional coupler ( control stuff works out around $100.00) and some good luck to automate the process on my 5 meter diameter octagon . Take your time and enjoy the next several decades getting it right , if all else fails a vertical metal flag pole and a base mounted auto tuner over some radials works well and you look patriotic with that big flag thrashing away in the wind
get back to us if there are more questions
Barry

[VK2FABS]

Thanks Barry! I think you are right, this is not an instant gratification activity. I can see how it'll take a good while to find a functional antenna setup for my situation. As for the links, unfortunately I don't think those loop dimensions are going to fit in my roof space. AlexLoop's design looked to be of a suitable dimension but needs regular tuning. Considerations and considerations...
http://www.alexloop.com/

[VK3YE]

Thanks Barry! I think you are right, this is not an instant gratification activity. I can see how it'll take a good while to find a functional antenna setup for my situation. As for the links, unfortunately I don't think those loop dimensions are going to fit in my roof space. AlexLoop's design looked to be of a suitable dimension but needs regular tuning. Considerations and considerations...
http://www.alexloop.com/

Alexloop is a good antenna for pedestrian mobile if you're pushed for space and need something collapsible for travelling. However it is quite expensive.

If you don't need something collapsible then there's cheaper and/or better options to build. For example:

* A homebrew version of the Alexloop that can be built for maybe 1/10 the cost. Most parts (except the variable capacitor and coax cable) come from Bunnings. It's a similar size but being one piece solid metal (not coax) it does not fold up. http://home.alphalink.com.au/~parkerp/p ... rojmal.htm

* A single band magnetic loop for 7 MHz. More heavily built and more efficient than the above. Can be put out on the patio or maybe the roof space. Limited bandwidth so some sort of remote tuning mechanism is preferred but not mandatory. You can have a lot of fun even with just a 20kHz slice of 7 MHz. https://www.youtube.com/watch?v=Cv_RnLpZ9gw

Note that the Alexloop (and other magnetic loops) sit at one extreme of the size spectrum. A full sized dipole is nearer the other. I can't help thinking that if you've got 10m of space something bigger than a loop may be a more efficient use of it.

[VK4TI]

Thanks Barry! I think you are right, this is not an instant gratification activity. I can see how it'll take a good while to find a functional antenna setup for my situation. As for the links, unfortunately I don't think those loop dimensions are going to fit in my roof space. AlexLoop's design looked to be of a suitable dimension but needs regular tuning. Considerations and considerations...
http://www.alexloop.com/

First thing is to get listening , perhaps a simple loop feed with a balun set on some dowels about the house gutter made from magnet wire , basically invisible and dead cheapl
until you upgrade power wise I cant see an issue although the covenants are irritating there are ways as you are discovering , fyi my large loop is made of 13 metres of 32mm heavy alloy tube , I have another made from some scrap 25mm alloy tube scrounged from a plumber supply about 1.5 meters high tuned with an old broadcast cap which works well for portable use on the car at 100 watts , I fitted a dc motor to turn the cap with a simple switch to save reaching outside the car , with your roof space a dipole fan might be possible assuming the roof is not metal (tile) ?

[VK2FABS]

Note that the Alexloop (and other magnetic loops) sit at one extreme of the size spectrum. A full sized dipole is nearer the other. I can't help thinking that if you've got 10m of space something bigger than a loop may be a more efficient use of it.

Fair consideration. Two issues here. 1) I'd like to avoid using the roof space if I can avoid it. 2) Whilst the roof space is 10m long, it's no where as wide. It's also largely obstructed by the beams and trusses, so the actual usable space, especially a 3D object is much more limited. It should be able to accommodate a fan dipole with a bit of crawling around.

I like the size of your magnetic loop and the "price". Will examine it closer. Is the location of the capacitive tuner a little too close? I read that hand position may affect the tuning. Further, I understand the radiation risks of this kind of antenna is significant. So maybe best to stay at a little distance. Maybe less of an issue on 5W transmitter.

[VK2FABS]

...with your roof space a dipole fan might be possible assuming the roof is not metal (tile) ?

Good question on the roofing construction. Whilst I haven't been up there for about 6 months or more, I recall it has some kind of covering material under the tile, a silvery metallic reflective looking sheet. Now I remembered it, I am wondering if it'll impede RF? If that's the case, I'm going to be back to square one on the roof antenna idea. Ouch!

[VK4TI]

...with your roof space a dipole fan might be possible assuming the roof is not metal (tile) ?

Good question on the roofing construction. Whilst I haven't been up there for about 6 months or more, I recall it has some kind of covering material under the tile, a silvery metallic reflective looking sheet. Now I remembered it, I am wondering if it'll impede RF? If that's the case, I'm going to be back to square one on the roof antenna idea. Ouch![/quote]
So it's a reasonably new home with some sort of metal coated insulation inside the roof as required these days , bears testing but I seriously doubt you can install an antenna in there , peruse the roof for mounting points enabling the mounting of a dipole along the ridge perhaps ? maybe a metal clip under some capping tiles with some fibreglass poles to hold it up ?

[VK2FABS]

So it's a reasonably new home with some sort of metal coated insulation inside the roof as required these days , bears testing but I seriously doubt you can install an antenna in there , peruse the roof for mounting points enabling the mounting of a dipole along the ridge perhaps ? maybe a metal clip under some capping tiles with some fibreglass poles to hold it up ?

Yes, around 15-16 years construction. Searched on the net, it's suggestive of some kind of aluminium coated insulation. Not promising.

Found another mobile antenna - TW Antenna (http://www.twantennas.com). Looks like sellers know that a functional compact antenna can be priced through the roof. Expensive!

[VK4WDM]

I would definitely avoid the roof space!

If its a tile roof you could try a very simple 40m dipole spread over the tiles, or better still held just above the tiles with some PVC pipe spacers. It would also work well on 15m. It does not need to be straight, zig zag it if need be. A square or triangular loop would also be worth trying. Use a balun (1:1 for dipole, 2:1 for loop, both easily made) at the feed point and back that up with a choke or "ugly balun" which is only a few turns of the coax on a PVC former, to stop "common-mode currents" on the feed line messing up your tuning (I use a choke on all antennas).

Do you have a lawn or a patio? If so the wire vertical might be the way to go. I am amazed how well my portable one works: 9m of insulated wire taped to a telescopic fibre-glass pole (like a "squid pole"), the butt end in a flowerpot full of stones etc to support it, and a couple of radials. If there is a tree available I dispense with the pole and just chuck the end of the wire up into the tree. I tune it with an auto tuner just because I have one, but any tuner would do.

73

Wayne VK4WDM

[VK2FABS]

Thanks Wayne. Unfortunately I have to work within the constraints of a strata environment, which means that I can't be overt with my antenna installation. So definitely no antenna on the roof. I do have an open balcony and I suspect that's where my best chance will be. It's surrounded by steel barriers which will add another layer of challenge if I want to keep the antenna low profile. Painful! Maybe I should just buy a large plot on the Blue Mountains or by the sea and move house.

[VK2HRX]

Other ways of thinking of this situation in strata locations are to set yourself up to operate mainly portable or establish a remote station at a better RF site. Both are fun to try.