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HF antennas on short masts

I have a “7.2m” pole that I purchased a several years ago. This summer, I figured I’d grab a second one as a backup so I bought one of these from this same seller. The “7.2m” pole only extended to just under 5m. I was significantly shorter than my old pole (and my old pole has 2 sections removed). I see the seller has updated the listing with a disclaimer after I left him negative feedback, but the table he has on there is still inaccurate.

There are some poles out there that are a bit closer to 7m, but you have to dig for them, and they cost a bit more.

-Doug, ND9Q

I just found a new possibly ideal mast for SOTA wire antennas:

DECATHLON now has 6m rod made from carbon fibre that is

  • 6 m long
  • 40.5 cm length for transport
  • 322 g

It is 40 EUR:

Compare to the 6m mast from lamdahalbe.de, this is a massive reduction. The lamdahalbe mast is 57 cm long an weighs ca. 600 g.

Martin, DK3IT

Hi Martin

I use Decathlon’s fibreglass poles.
The short traveling pole LAKESIDE-1 TRAVEL 600 when taking a flight…
The “long” for other activation CAPERLAN Pole 600 Still Fishing Press-fit Rod

Do you notice any change in the antenna performance from fibreglass to carbon one’s?

73
Pedro, CT1DBS/CU3HF

Hello Martin.

Looking at the pictures in the ad, I can’t see this mast supporting anything with any weight. Perhaps a very lightweight 1/4 wave vertical down the pole but not an Inverted V dipole.

73 Ed.

Maybe not the best material to use for a vertical antenna support.

Hi, regarding carbon fiber masts:

We discussed this here:

I see the theoretical point, but we will have to check how much of an effect that is in practice. In a couple of weeks, I should have two identical sets of 5 and 6 m masts in glass-fiber and carbon fiber and could make a comparison.

Regarding Pedro’s question: The main difference between the old GfK rods and the new carbon-fiber masts from Decathlon seems to be that the latter ones weigh about 50 % of the former an, more importantly for me, are much shorter for transport. 40cm is really neat in a rucksack or carry-on luggage. 57 cm is already borderline even in a trolly, and will stick out of many small and medium-sized packpacks.

As for Ed’s comment: Yes, I guess a dipole cannot be mounted at the top segment, but keep in mind that:

  1. The carbon-fiber version has many more segments (i guess 11 instead of 6 or so), so just taking the second thinnest will mean a reduction of only 40 cm or so.
  2. The 6m version is lighter and shorter than the 5m Gfk versions from DECATHLON and lamdahalbe, so I guess it will be a net gain even if you have to go down a foot or two.
  3. I am now often using verticals, and those have a minimal load on the tip if you add a rubber band or something similar a meter or so below the tip so that the full weight of the wire is not hanging on the tip.

Martin

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I worked with Japan from US West coast on 30 Meter with dipole 2,5 meters above the ground and 2,5 W output power. If you have the right conditions - antenna heights above the gorund is not the main factor.

I thought I’d been involved in a discussion about that. It’s an age thing… :wink:

Before you carry any pole on an aircraft as hand luggage, I’d check with your airline.
I bought a travel pole for that very reason, but never got to take it on board an aircraft as it is not permitted in the cabin…
Of course neither are walking poles or umbrellas, so it’s far easier just to find a support when you get to the end of your journey :slight_smile:

And I’ve done loads of 60m activations with the antenna lying on the ground.

I normally pack my mast in my hold luggage. OK this doesn’t help those travelling light with only carry on baggage but normally I need a case for a few days away, so a hold bag takes anything that is not allowed in the cabin but is still allowed on the plane.

Ed.

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Contrary to what Peter says it is a fact I (and I know others) have never been stopped or questioned about taking a 57cm (length when telescoped) 5m long fishing pole which fits inside my rucksack on lots of Ryanair and Easyjet flights over the last five years, the last time was in May this year. I get my poles from Life’s a Breeze. I always keep the rucksack on my back when going through the final departure gate and despite the sack being around 5 cm over length its size has never been challenged by gate or cabin staff. Despite being 5cm over length (Berghaus 35+8 rucksack) it will easily fit end on in the overhead locker.

Laterly on these budget flights I have tended to pay the few pounds extra to get priority boarding then I am through the gate first and am guaranteed room in the overhead lockers, rather than be forced to put the hand luggage in the hold, which of course one cannot do because of the lithium batteries being carried. I have a preference for Ryanair over Easyjet as on Ryanair as well as being allowed 10Kgs weight in the rucksack, you are allowed (at no extra cost) to take a small carry on bag with unlimited weight. A bag of the size allowed can take around 7 Kgs of electronic equipment, such as transceiver, batteries, camera. GPS, Satnav etc. On Easyjet you do not get the option of a free second bag, so everything has to go inside the rucksack or in pockets. The advantage with that over Ryanair is that their is no restriction on the weight of the rucksack. For a short SOTA Tour of 4-5 days with clothing and radio gear my rucksack normally weighs in at around 13-15 Kgs.

Just out of interest has any activator been prevented from carrying on one of the short poles inside a rucksack?

PS Having just read Ed’s reply I prefer not to take a hold bag for short tours if I can. This saves waiting around at the carousel for the bag and the significant cost of taking the hold bag. Not having one allows you to get to the car hire desk and to the first summit more quickly! It is not unusual to fly say to Czech Republic from the UK for less than £50 return - take a bag and it will likely cost another £20 - £35.

73 Phil G4OBK

2 Likes

Phil, that’s good to hear.
I only had the one pole taken by airport security, and after reading the rules, and talking to the supervisor at security themselves, decided it was too much effort to repeat.
I’d actually prefer if you could take walking poles, which would serve a multipurpose function.
I’ve also had all my thin polyester guy lines confiscated, but strangely not the 20m of 7x0.2 wire they were packed with…

And no one blinks an eye at an Altoids tin with wires and electronics stuffed inside :slight_smile:

Hi all:
FYI: I got my 5 m carbon mast from DAM a couple of days:

While a systematic test of the impact of the carbon fiber material on my vertical antenna is still to be done, I can say that:

  1. The mast is super-compact in comparison to the 5m and 6m masts from lambdahalbe, and a lot lighter. It really makes a difference towards lightweight operations.

  2. The material is a lot stiffer (yet not brittle) so that even the fine 1mm top segment holds my vertical wire straight up, and it might even be possible to attach a lightweight dipole to the very top segment.

It is definitely a keeper, and I now ordered a similar 6m version from Decathlon:

73 de Martin, DK3IT

Hi Martin,
that link to ebay says the 5m mast is UKL58 plus UKL15 shipping - that’s expensive compared to the EURO 32 (+shipping) for the longer 6m mast from LambdaHalbe! I suppose if it’s stronger and lighter it may be worth the extra money.

I’ll be interested what you find with the caperlan mast at EURO 40 with free shipping it’s about the same price as LambdaHalbe (but it’s currently out of stock).

73 Ed.

Hi Ed,

indeed, the DAM rod offer on ebay is a bit pricey. When I initially researched this rod, it was ca. 35 EUR + shipping from Germany. But then the delivery was delayed again and again with a final delivery promised for January. So I decided to cancel the order and buy it from the few suppliers who had it on stock, because I did not want to wait 2 - 3 months.

DECATHLON also has a 5 m version with very similar features for 30 EUR:

But by the time I found that I had already ordered the DAM one.

The real point I am trying to make, though, is that if the carbon fiber material has no significant effect on the performance of the antenna, then these masts are a huge improvement over the ones from lambdahalbe.de. They are about half the weight and 60 % the travel length.

73 de Martin, DK3IT

Hi all,

attached, please find a picture that gives an impression of how much smaller the 5m DAM carbon pole is in comparison to the masts from lambdahalbe.de.

From top:

  1. 6m lambdahalbe, 603 g
  2. 5m lambdhalbe, 420 g
  3. 5m DAM Pocket Pole, 213 g

Of course the open question is how well the carbon fiber masts will work with vertical wire antennas. Theory tells us that we might face a couple of problems, at least one of the following:

  • The antenna wire might be coupled capacitively to the conductive mast, shifting the impedance and possible creating a shunt to ground if the mast is not properly insulated from ground.
  • RF might be reflected from the mast and cancel out RF from the antenna wire (in the sense of an “image antenna”).

Given the improvement in terms of weight and size, I am seriously interested in learning

a) how significant the effects are and
b) whether we can mitigate them.

For a), I plan to set up two identical wire antennas for 20m and attach them to two WSPRlite devices and measure the difference. I already did a few tests and got quite acceptable results. Without a systematic approach, however, they are not very useful.

On the Web, there is a wide range of opinions about carbon-fiber near antennas; many quadro-copter fans report problems with antennas behind or near carbon-fiber parts (but then again, they work at 2.4 GHz, and the materials used might be very different in terms of geometry and resin vs. carbon ratio etc.). Also, the rod elements are much thinner. Some hams report no problems except for a slight detuning.

Should the problems be significant, one could think of the following countermeasures:

1.Vary the distance between wire and mast, e.g. by attaching it close to the rod vs. using small spacers or sloping it slightly.
2. Insulating the lowest segment by adding a layer of shrink tube.
3. Connecting the rod to the wire electrically so that it becomes part of the radiator (but then again the question is how well the joints between the segments form an electric connection).

Any ideas and experiences will be very welcome!

73 de Martin, DK3IT

2 Likes

Hi Martin,
as usual, a very deep and precise approach!

Sorry, I haven’t got any experience yet on Carbon fiber poles, but I’m planning to try one for my inverted Vee End fed half wave. I guess that such configuration wouldn’t produce any detuning at all!

If I can do further tests for a vertical I’ll give it a go and tell here.

Look forward your WSPRlite results, good luck!
73 de Ignacio

Hi Martin,
Very interesting indeed. Looking forward to hearing from you.
73 Fabio

IMHO, the perfect way to use these carbon masts is with end-fed antennas: anchor the end of the antenna wire to the pole at 1-2m height and run the wire out through some kind of loop attached to the top of the carbon pole. Bring the antenna wire away from the pole with a little tension, forcing the pole to bend into an arc. The wire will form an inverted vee shape and will be separated from the arc of the pole. Fred KT5X originally promoted this scheme because it fits in so well with his ultra-lightweight packing scheme and I tried to copy it with great results.

73, Barry N1EU

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Andy,

I have been using a link dipole (looks like an inverted vee) for all bands 40-6M, apex at 12 feet, since April of 2013 for SOTA. I have made over 9000 QSO’s, which includes Summit To Summit contacts with VK2, ZL, G, GW, S5, DL, HB9, KH6, KP4, and OE. Almost all QSO’s are QRP…a few running 25 watts or so (turns out the extra wattage is also not very important when using CW).

So, short story is that short dipoles work very well, and are easy to make and deploy.

Having said that, more antenna height is always better, but 3 db harder to deploy in the field.

Good luck!

73
Pete
WA7JTM

1 Like