New antenna design website

Now, I need to preface this announcement with this observation: that I dislike calling attention to something I’ve developed and built myself, but it would seem that others are, understandably, even more reluctant to make the announcement themselves. So here goes…

There exists, for good or worse, a new wire-antenna design website aimed at portable radio activists. The site, to be found at

is still in development stage, but nonetheless works well enough to withstand some heavy use. Four different antenna types for HF use are currently supported:

  • linked dipoles (this is intended to replace the SMP extras page Linked Dipole Designer)
  • EFHW (end-fed half-wave) antennas
  • vertically-polarized delta-loops
  • half-square antennas

with a fifth - OCFD antennas - in development. All of these antenna types have been discussed in various Reflector threads, so they should be familiar to many.

Using any of the “designers” (i.e. one of the pages within the site), one can quickly specify an antenna of the designated type, experiment with various combinations of antenna section lengths or angles, choose from one of several ground types, and run a calculation which displays various antenna performance charts and diagrams. These diagrams include:

  • azimuth, elevation and 3D propagation patterns
  • VSWR curves, for one or several bands depending on antenna type, and including resistance and reactance (Re/Im) curves
  • an antenna currents diagram
  • a Smith chart

A couple of screenshots may whet the appetite for those interested in exploring what the site has to offer:

An example designer inputs area

An example designer options area

An example VSWR chart

What’s the point of this site?

It’s acknowledged that a number of NEC-based programs and apps exist, which can model antennas such as these (and a whole lot more besides!) but many would agree that they require a steep learning curve to become familiar with them to the point that they become less daunting to use, and many potential users are discouraged from using them.

Think of this new site as a “half-way” house which takes away a lot of the complexity of designing antennas like these, and yet still present NEC-based and NEC-calculated results. Be aware though, that since this is not a native executable optimized for a particular operating system, but runs in the interwebs, it runs rather more slowly than the optimized program … but it gets the job done. YMMV, as always.

More usefully, it serves as a “playground” where antenna specifications can be altered to see how propagation patterns, VSWR, etc. change with those alterations. Even if one doesn’t actually build the antenna, a lot can nonetheless be learned about antenna performance this way - I know I’ve learned a lot more than I did before about antenna performance and about antenna electrical properties while building and testing the site.

OK, that should do to start a few tongues wagging. Thanks for your time in casting a glance over this…

Cheers, Rob


Excellent Rob, well done and thanks. I look forward to checking it out.

I’m a great believer in measure twice, cut once. Believer but not often practitioner :wink:


Excellent tool.
thanks for sharing.



Hi Rob, thanks for your antenna design software page. You have done an excellent job with this program, thanks for your effort. :clap:

Geoff vk3sq

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I just looked at your new website, and you have created a wonderful set of tools. I started using EZNEC when it was ELNEC, on a DOS computer with a 286 co-processor. The learning curve was indeed steep, and I know I missed a lot.

For portable operating we now have a more specialized environment, and anyone familiar with basic antennas and theory can just jump in and go. I think your work will help many, and take us closer to truth in the field.

As we move into fall and winter, i plan to enjoy using your tools!




After trying it out for the first time, I find this to be an ingenious toolbox, e.g. for non-EZNEC experts or simply to play with it in a convenient way.

Remarkable: EFHW antennas in an inv-L arrangement can also be tilted and the ratio of vertical and horizontal parts can be varied.
Of course, you can’t simulate my 10.90m multi-band inv-L antenna tilted by 25 degrees, which is not (yet) used by this tool.

A really good idea and implementation, congratulations on that.

Yes, the name “sota antennas” is unfortunately not exactly my preference. Practicing portable radio for almost 50 years now, I would prefer the name “portable antennas”. This name generally refers to antennas that are portable in terms of weight and do not exactly suggest buried radials, hi.

It is also undisputed that portable antennas can be used just as successfully at home in the garden, at GMA, IOTA, POTA, COTA, … - which of course also applies to sota antennas …

In my opinion, the name prefix SOTA is a clever marketing ploy used by providers. In addition to SOTA antennas, there are now also SOTA sunglasses, pocket knives, compass, cell phones, drinking bottles, cookware, backpacks, etc.

And don’t forget the well-known provider SOTABEAMS, which doesn’t exclusively offer beam antennas, hi.

73 tks, Heinz


Hi Heinz,
SOTA of course also stands for “State Of The Art”.

73 Ed.


Hi Heinz,

Many thanks for your very encouraging remarks, they are most welcome! As I’m sure you can understand, one can have the idea for such a site, begin to develop it, then extend it, and all the time wonder whether people might just deride it for being superfluous, or unnecessary, or badly presented, or just providing inaccurate results. Being more of a website developer than an equipment expert, there’s always this fear at the back of my mind, hi. I await the input from the pro’s - especially those redoubtable personages familiar with EFHWs (surely a dark art!) - with bated breath!

I’m with you on that, and have already considered the name - I’ll look into the options available. Perhaps others might wish to weigh in on the name? (Heinz is referring to the remarks, on the choice of site-name, to be found in the site’s home page…)

I’m not exactly sure what you mean by this - could you be a little more explicit? It is certainly possible to use the EFHW designer to tilt an entire EFHW antenna by 20 degrees downward/clockwise - perhaps you mean upward/anticlockwise? - if so, that option could easily be included.

UPDATE: the domain [portable - antennas dot com] has now been registered, but will not be available for this site for up to several days…

Cheers, Rob

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AFAIU we have a trademark on SOTA when applied to radio (but I could be wrong). I see no problem it being used this way by Rob’s website. But trademarks require protecting so if Rob would kindly ask via the contact MT form to use it in his URL we can give him the thumbs up. That way all bases are covered.


Hi Andy,

Thanks for pointing this error out - I’ve sent a request to the MT via the contact form as you suggest.

Cheers, Rob

PS - I see that the SOTA Contact Form doesn’t send a confirmation email to the person posting the contact message. It was pointed out years ago to the SOTA webmaster that a user can have no real indication that the Contact form the user has just submitted actually got to the intended recipient - notwithstanding the friendly thank-you message which appears on the screen: it’s perfectly possible for the script to fail after posting the thank-you message.

If a confirmation email is sent to the user, there’s a good chance of them receiving it (if it gets past spam filters and the like), and this will put the user at some ease that the Contact form has actually worked properly - there are many online which don’t. YMMV, as always…

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The mentioned 10.90m multi-band inv-L antenna, tilted by approx. 25 degrees, belongs to the family of vertical antennas. The antenna has an apex height of 6m, is fed at the base (connected directly to the ATU/TRX) and requires radials. For 80 and 60m the antenna has switchable loading coils, to increase the radiation resistance to a value close to that of a quarter wave vertical.
You could also call this inv-L antenna an inclined and angled multi-band vertical antenna, but that would be a real tongue twister, hi.

BTW, This multi-band inv-L antenna has a long development history and was developed by EZNEC to meet the special needs of Bruno@HB9CBR at, yes, SOTA, hi and WWFF in terms of the best length, geometry, radiation angles and gain. Of course, this antenna also covers my needs for “ordinary” portable radio, hi.
Because this inv-L antenna is now used by some colleagues, there are always individual adjustment requests (e.g. questions like: what happens with fewer/shorter radials or with an apex height of only 4.75m).

Because portable vertical antennas are also used by many portable radio operators, it would certainly be desirable if this type of antenna could also be supported by your tool.

73, Heinz

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Just a short message to announce that the MT has very kindly given me permission to use the SOTA name in the site. I should really have checked this BEFORE starting to use the name, but I’m not the most organized of people at the best of times…

Thanks to the MT!

Cheers, Rob


@DM1CM Thanks for sharing. My antenna skills on a scale of 1 -10, I’m a 1. I’m hoping your link will help me out.

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OK, I get it now. Thanks for the excellent diagram which shows the configuration very well. To be honest, I would say that this is a very specialized antenna, optimized as you say for various combinations of bands and numbers of radials. Probably too specialized for my little site, but who knows? - a page for verticals is obviously lacking in the site, and this kind of thing gives me some impetus for considering including them at some point.

Thanks for sharing!

Cheers, Rob


Wonderfully easy to use site - after years of batting with EZNEC

Like everyone I have my own feature request list;

  1. The ability to set that inductive load to 0 (or remove it) in the EFHW designer so I can model my own antennas which do not include such a load.
  2. The ability to specify the transformer matching ratio

Wait for your OCFD version with anticipation - mainly for insights as to why my OCFD for 60m performs as it does.

Feel free to ignore all of the above except the bit saying thanks for the great tool!


Hi Matt, glad you like the site, and thanks for the kind words of appreciation! Well, it was certainly one of my goals, to make it easier to use than the NEC-based programs for the kinds of simple wire antennas that many SOTA (and POTA, WFF, GMA, etc.) activators regularly use.

As to your two feature requests for the EFHW designer, I had already anticipated both of them while developing the page, but haven’t yet implemented them - but I was waiting for such input from those who actually build them and use them. Very valuable input, thanks!

Cheers, Rob

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These features have now been implemented.

Cheers, Rob


If you have a webform that allows someone to enter the email address manually rather than responding to an incoming email and that webform sends an acknowledgement email to the address entered, then you open yourself up for people to abuse the form and target some third-party email address and flood that inbox by refreshing the page over and over again resulting in lots of emails being sent by us. This can DDOS that email account by filling the inbox and taking it off-line and get our outbound email server banned from sending mail.

So it doesn’t send a confirmation mail and you need to have faith that everything has worked. Which is does 99.99999999999999% of the time.

We could write lots of software to to handle this method of contacting the MT and we could make the system perfect. As we all know, “perfect” is the arch enemy of “good enough”.

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Fair comment, thanks Andy.

That is an excellent tool Rob, congratulations!
Thanks for the work involved and for sharing it. I’m sure I’ll play with that.

73 Ignacio

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