Other SOTA sites: SOTAwatch | SOTA Home | Database | Video | Photos | Shop | Mapping | FAQs | Facebook | Contact SOTA

Lightweight Vertical Antennas


#1

Hi everyone, I’m wondering about others experiences with lightweight vertical antennas? What options are there out there? I have heard of people getting a telescopic fishing rod and running a wire, and I have seen videos of the MFJ-1979 (which looks like an awesome and simple solution).

What about hardware and loading coils? It would be great to have the option to go to lower bands as well.

My main reason is some summits I have scaled have not had anywhere (rocky summits), or anywhere convenient (short trees, bushes, busy with visitors, etc) to put up a dipole or squidpole. A vertical with some sort of bracket may be able to be shoved between rocks or attached to a short stake in the ground. And there’s also long skip.

Thanks, VK3TST.


EFHW Dipole - Mono Band Version
#2

This is a good starting point, I’ve made a copy and it works well for me.

Brian


#3

Hi

I predominantly use verticals on all bands above 40m.

The first thing to realise is that all antenna systems that are used for portable operation are going to be compromised in some way so try not to make your antenna too complicated. This suggests a resonant design for different bands; try to avoid lossy coils and traps.

In an ideal situation it would be nice to have 1/4 wave antennas with sloping radials but it is really not easy to do on bands below 20m with short poles.

As an example I use a full 1/4 wave antenna on 40 metres with the radiator 9.5 metres long and wrapped around a 10 metre fibreglass fishing pole. There is no way of having elevated radials so I just run three resonant radials from the base at ground level. Does it work…? Just look at my activator logs.



40 metre vertical on Pen-y-Ghent; the radials have just been thrown across the snow!

On holiday the two main bands I tend to use are 20 and 17 metres, again vertical but with links to change bands. This time I use a 5m travel pole (1/4 wave at 20 metres) with resonant radials along the ground.



20/17 metre vertical in Lanzarote; you can just see two of the red radials on the ground. Some rocks were used to restrain the guy-lines

In both cases the antennas show a good match to 50 ohm regardless of the terrain the antenna is used over. This is essential for me because one of my amplifiers will fail if the VSWR is too high.

The easiest way to hold it up is to use three guy-lines pegged with tent pegs or tied to anything suitable at the location.

So decide on the bands you want to use, choose the pole you want to carry and go and cut some wire and experiment.

Carolyn


#4

Radials on the ground means high losses (unless you have at least 20-30 of them), I always try to have them at least 30-40cm above ground if possible.

My solution is to use a random length of vertical wire (about 6,5m), 2x 4m long radials and a tuner close to the base of the antenna (just 50-60cm of coax). I generally use a 7m fishing pole to support it, but I at some point I just used to throw the wire into a tall tree (not the best solution, the wire sometimes gets tangled badly in the branches).


#5

That assumption is based on a good, ideal “ground”… most summits are very very poor “ground”, even the wet ones.


#6

Today I started to write up my SOTA antenna for 40-6m:

73 de Dominik, HB9CZF


#7

I’ve been looking at doing a loaded vertical like this with a 3m pole I have, used to be a bit longer until snapped the bottom section, but it is only 90g total weight. I’m not the biggest fan of loading, it’s just an idea…

I do have a 10m mast but it’s not lightweight by any means.

Precisely what I want to do, currently the EFHW takes time to string out, throw through trees and or put up a mast. It’s why I was looking at the MFJ 5m telescopic steel whip; that plus a base and some radials and I’m on air ASAP. I’m not getting rid of the EFHW or dipole, just looking for another option.

And in VK pretty much all soil is poor, very very old dirt. Although I found out recently there is a good patch where they built the Radio Australia transmitter antenna array.

There’s a few things going on with the idea behind this antenna. Firstly long hikes, I did a 10 day hike at the start of the year and ended up with 4kg of radio gear, since then I have been learning Morse and looking at radios like the Mountain Topper; and how to keep gear for a future hike about or under 1kg. On that same trip I saw some of the hardest summits to operate from, rocks and no dirt and nowhere to string up a mast, if I dropped my 817 in the wrong place it would have been gone for a very ling time. And I saw this video on YouTube https://youtu.be/zn0W1YOX47A (jump to 1:00 so see his antenna being set up); reminded me that verticals can be easy to set up and suit some places better than dipoles.

Thanks for all the replies so far!


#8

Bad ground (rocks, sand, concrete etc) absorbs the energy radiated by the antenna, while good ground (rich pastoral ground or salt water) reflects it back into the air. To minimise the energy that ends up heating the ground you want either to have your antenna as far from the ground as possible, or to add (an impractical number of) radials that block the radiated energy from reaching the ground. Even 50cm make a significant difference compared to ground-mounting (the height-losses relationship is exponential).

Cheers,
Razvan.


#9

I understand what you are saying, but practicality, for me, over-rides the desire to have antennas high in the air. I want to keep total radio gear weight below 1.5kg; even if I have to make 20 1.5m radials vs 4 5m radials for a 20m quarter wave. The flip side with something like a dipole or EFHW is that the trees the antenna is in will absorb RF as well, and the EFHW L-match will also absorb some of the transmit energy.

As a side note when I did my hiking trip there was only one summit I managed to scale, and all I had was an EFHW element over the rocks. I can imagine just laying on the rocks probably lost me 10dB. On the day conditions were horrible on HF and a K-index of about 9 at my location, I think the 40 & 15m contacts I made were line of sight. Any vertical element with at least 3 radials would have been significantly better.


#10

[quote=“VK3TST, post:9, topic:12616”]The flip side with something like a dipole or EFHW[/quote]I’ve had more trouble with verticals than with dipoles in among lots of trees; something to do with the vertical and all that sap wood being more or less parallel, I guess. These days I try to get the antenna wire perpendicular to any trees if possible…


#11

In the UK summits with lots of trees are in a small minority and are mainly single point summits.

Brian


#12

[quote=“G8ADD, post:11, topic:12616”]in a small minority[/quote]Mostly the ones nearest my QTH, I guess. Mind, some of my nearest summits are the other side of the Channel… :wink:


#13

Nothing like building a portable antenna and getting it to work.

Mine be 1/4w vert and 1/2w inverted L both 40m
BUT can tune the old girls from 80 to 10 with ease

Dead easy to make and carry about etc. But with end feds its advise able to have good 9:1 unun with counter poise points.

Recently i have made me counterpoise wires from one long 11m wire ( 1/4w of 40m)
and cut them ito 4 lengths totaling the 11m wire but in four different directions certainly makes a difference from the one long wire i had before even on the 1/2w In/L. But i want to op on 80m I have made extensions so can make them longer. The counter poises that is

I use an 8m sqiud pole and 5m up it is its support with the coil around a plastic pipe to shorted it down the 11m to 8m but antenna is still 11m long over all. Keeps wire tidy have enough to reach the top and enough coming out of bottom to reach the Unun.

Do note the base is not the same any more but this shows where the coil is as is spaced around a 50mm plastic pipe this is where you lose the extra 3m of length.

if ya want more details drop e a line and i can send you a word file showing how its made

Have fun making an antenna and getting it to work. so many different ways you can make one this is just one of

karl


#14

Hi Marcus

I used a JAC 3 portable antenna from a summit got it from hamradioinfinity, used it from a few summits tends to work best on 20-10m with pre measured radials along the ground. This uses a a ground spike also similar to the idea you have took me 5 mins to find a patch of ground once to put the spike, I wouldn’t like to risk the antenna whip on a windy day, I use it now from the vehicle when parked up.


#15

Yet again, the same topic and the same answers!

Stick to dipoles, they’re proven and easy to set up. I don’t know why people say they are hard to put up, they are not! A pole and three pegs are the only hardware you need. Use the dipole antenna as guy lines for the pole, job done!

No need for tuner. No need for radials. Good match to coax, easy to feed from rig.

Verticals - they belong at the beach dipping their toes in the cool saltwater!

73, Colin M1BUU


#16

At the risk of repeating myself, There have been instances where I cannot put up a pole and peg it out, this is what one particular summit looked like: https://goo.gl/photos/8BnHBhrru3fRBq7A6. The bushes you see are growing on and in between the rocks, that I could tell, there was no dirt holding the rocks up, that had all been washed away probably a few thousand years ago.

You can’t see it in the photo, but there is a blue wire running just to the right of the middle, that was my EFHW just laying on the rocks; and I did manage 4 contacts over 3 hours in very trying band conditions.


#17

I can’t see any problem there. Wedge the pole and/or keep the guys in place with loose rocks. Works for me on rock summits, extinct volcanoes etc.


#18

Nice photo. That summit could be the twin of Elidir Fawr GW/NW-005. I have never failed to support a mast on such summits (plus EA8/LA summits which are worse). Just tie a loop in the end of the guy ropes, pull the rope (string) through the loop and use a handy rock to secure.


#19

There is a detached boulder or finger of rock on the right hand side of the photo that would support a pole with the addition of a couple of bungees.

Brian


#20