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My sota antennas


#21

I think it can be helpful and educational (and dare I say fun) to sit and have discussions about antennas and the math behind them. However, In some cases like this, I think it is a little like arguing about what sports car is better based on the published specifications when, in fact, the best thing to do is get out and drive.

I would suggest just picking something “good,” get out there, and dont look back for a while. With experience and/or a desire to tinker at a later point, you may try different things, but just picking something and going with it will pay far more educational dividends than constantly changing. In this hobby and many others I have been in, people look for the perfect killer antenna or recipe or whatever. The truth is, it doesnt exist.

I currently use a resonant EFHW with a home built 64:1 unun. In just getting out and using it, I have learned a lot about it and have been doing well with it. Is there something better out there? Maybe. Is there something better out there for me? No, not currenty.

2 cents from someone who is also on the journey.

-Steve
W2SWA


#22

Excellent advice :+1:


#23

Couldn’t agree more! Any antenna that’s in the air and connected to a radio is infinitely more effective than the best of super-antennas you’re thinking of building :wink:


#24

Yes!

I would like to stress that for a SOTA antenna, theoretical efficiency is only one of the many variables for its actual usefulness and performance. In my SOTA antenna projects, I now tend to start with what is doable from the perspective of handling and then test whether it works sufficiently well. For instance, my two SOTA vertical designs:

are mainly inspired by an optimized handing on small or crowded summits. They are less performant than a full-size dipole (center-fed or endfed), but in practice, I can manage more QSOs on a challenging summit because I am QRV within 1 - 2 minutes. Still, I can work @SP9AMH with QRP2QRP regularly.

A dipole / EFHW with traps might be a little less efficient than a linked dipole. But when in a hurry on a summit, the antenna with traps allows me trying for a nice DX catch on 20m at the end of an activation in winter in a few more minutes, while I would not have the time to take down the antenna for a band-change.

As for the “any antenna design works” argument, I think we should add that this is true as long as you do not make any mistake building and tuning it: If you just look for a low SWR, you may never notice very bad construction mistakes that cause a lot of losses, for instance

  • long coax for sections with a very different impedance from 50 ohms,
  • shorts or cold solder joints,
  • core losses,
  • capacitative coupling into nearby metal or otherwise conductive objects,

etc.

So a WSPR performance comparison against a reference design is always useful. Low SWR just assures an impedance match to the transceiver, so that the finals do not get blown away. 80 % of your antenna can be actually a dummy load, while you can still achieve a 1:1 SWR, as any full dummy loads proves.

73 de Martin, DK3IT


#25

Thanx for replies
I am in the process of building a pico trapped version
For more convenience and faster set up

Many thanxx
Iain


#26

I am using center feed dipoles for each band for many years. It requires to carry and install 3 antennas, but it does not require tuner.


#27

If you add two pairs of the SOTAbeams Pico Traps to your 40m center-fed dipole, you will be able to turn it into a very convenient 3-band antenna that does not require an ATU either.

See here:

You will only have to observe that

  • you have to tune it starting with the highest frequency and the traps and following wire segments already installed and
  • the resonant lengths will be a bit shorter than for a linked dipole because the inductances of the traps extend the respective segment electrically.

73 de Martin, DK3IT