Tag Archives: Vertical

Quarter Wave -vs- 5/8ths Wave Vertical


Compare Red 5/8th -vs- Blue W/wave

Anyone who has mucked about with verticals will no doubt have worked out that a full-sized quarter-wave for the 40m band, more or less tunes up for 15m band.

It wasn’t until my entry in IOTA Contest this year that I convinced myself that they are not a cloudburner (as many people suggest) but compare favorably with a quarter-wave, even producing more gain by 2 dB at 10 degrees above the horizon.

OK, so 2 dB isn’t a huge gain, but hey – it’s free. Take it when you can!

Don’t forget, you can do the same for 10m band too by making an element 6.83m long and folding it back a further 1.11m (for 28.5 MHz). So you’ll need nearly 8m of wire. Don’t forget, that’s insulated wire!

Quick SWR Calculator for Vertical and Dipole Ham Radio Antennas

Here’s a really simple way of double checking how to much to trim your antenna elements.

You only need to type in the numbers in the Cyan boxes.

Just type in where it is resonant right now – then type in where you would like it to be resonant and the spreadsheet will auto-calculate the trimming.

Film: How to use the SWR Adjustment calculator.

Adding 80m to DX Commander All Band Vertical (9-bands 80m through 6m)

Regulars will know about the DX Commanders very cool results which are now filtering through in real world successful contest scenarios.

My own issue is that I needed just one antenna that would deliver an all-band solution, certainly for the contest bands of 40m, 20m, 15m and 10m – but I also needed 80m in the mix too.

My holiday home has a very compact small garden so the option of putting up a dipole for 80m is out the question, but modelling suggested than exchanging the 30m element for an inverted L for 80m should work.

The 80m element therefore starts vertical, like all DX Commander elements and turns a sharp corner at 6.9m above ground and droops down for around 13m or so, hanging over a bush at around 3m off the ground. Probably not perfect but perfectly adequate to score 44 QSOs inside an hour on the Saturday eve of the IOTA contest. That score includes 16 different IOTA multipliers, certainly a wide spread around Europe.

Continue reading

DX Commander Contest Antenna achieves top placed UK IOTA Station

IOTA-graphicI’m absolutely delighted to report that I was placed 4th overall in the world for IOTA-Fixed station, Unassisted, Low Power, 12-hour section. This was from a holiday home and I installed the antenna inside 1-hour.

Results here  – but what makes this more remarkable is that I only used the one antenna from 80m through 10m; DX Commander All-Band-Vertical.

For 80m, I confirgured the DX Commander as an Inverted-L, replacing the 30m element. Of interest, 30m was still achievable (albeit with a 4:1 SWR). Although 17m is not a contest band, I did notice some slight interaction with the new 80m element, however SWR was still acceptable without an ATU.

I logged 300 QSOs however I notice after adjudication, that fell to 289. Pretty good, only dropping 11 QSOs. And I was amazed at how effective the 40m element produced such startling results on 15m, effectively as a 5/8th. Even 10m as a 2.5m long, ground mounted quarter-wave was getting in the action with short skip too.

All in all, I’m extremely delighted that I test-proved this antenna from a holiday location in competition with my peers, who were using genuine fixed-station antennas.

Software Modelling your Vertical antenna ground radials with MMANA

I’ve been scratching my head for years how to model an appropriate ground with my ground mounted Vertical Antenna radials.

I’d like to thank Sigi, DG9BFC for clearing this up for me.


NOTE: I like to draw a small feedpoint in all my HF antenna models, like a 5cm length of wire where my “source” (coax) is connected to. Particularly useful for fan dipoles and for making other adjustments. I’ve left that part out for simplicity on this How To since I’m trying to make this super easy.

Continue reading

Working 15m band on a 40m vertical antenna

Note: This article discusses the merits of a 3/4 (three quarter wave) vertical -vs- a 1/4 (quarter wave) antenna.

You can build a 40m vertical quarter wave antenna and ground mount it with 16 x 4m radials and operate it at the third harmonic; 21MHz.

Actually, all my experimentation has shown that if you multiply the quarter wave resonance by 3.03, you’ll have the next available usable band. In this case, if you tune a 40m vertical to 7.00Mhz, you’ll have the whole of the 15m band to play with with a centre-point of 21.300Mhz. Oh, and you’ll still have the whole of 40m band under 1.3:1.

Now here’s the controversy:

Most people who read antenna publications or the ARRL handbook believe that if you actually make this antenna, you’re creating a cloud-burner on 15m.

Technically correct (sort of) – but for DX, wrong.

On the surface, the 10m long 40m vertical that’s used on 21.225MHz does indeed look like a cloud burner. Here it is. 15m band in green -vs- a pure quarter-wave in red).


(click to expand quarter-wave in red, three-quarter wavelength in green)

Continue reading

Solarcon Imax 2000 Review 5/8ths Vertical Antenna 10m

Dsc_0002I always fancied a low-angle vertical for 10m band and after doing my research, came across the Solarcon Imax 2000. It was a toss up between this, a Sigma 4 copy or the Sirio 827. The Sigma 4 is now called the Sirio Vector 4000 and I discounted this one because of the size of the radials which seemed excessive for my plot , Same with the Sirio Vector 4000 which is just too tall. Even so, the Sirio Imax 2000 is still 24 feet in length. But read on, it’s actually fairly stealthy for such a tall antenna.

Continue reading

Salt spray detunes wires on fibreglass antenna poles

I use a lot of fibreglass poles with wires strewn up the sides, normally in a lazy helical fashion so that they don’t flap about too much.

I have great success with these poles as regular readers know however I have noticed that certainly wet weather can detune them ever so slightly. Effectively, they become slightly longer and I fathom that as the fibreglass supports become wet, I am achieving some slight inductance with the water that drips from the surface and gets between the wires and the poles. As soon as they are dry again, the tuning comes back to normal.  Continue reading

3 Element 40m Vertical Parasitic Array (VPA) Vertical Yagi

Essentially, this is a single 1/4 wave vertical antenna with ground radials, complimented by a pair of parasitic verticals; a reflector and a director. It will deliver around 6db of additional gain over a standard vertical with a beamwidth of around 70 degrees. I have built mine pointing 300 degrees so that I can work the US easily at night.

I call this the M0MCX VPA (Vertical Parasitic Array).


Hours of planning and modelling with MMANA has finally produced an excellent and extremely economical method of producing gain in one direction, although the front-to-back ratio isn’t superb, it still has some rejection.  Continue reading