I’m a noob as ham op (got my license in Sep.2023).
Until now I’ve been using my EFHW wire 40m antenna hunging it in a tree. I want a mast for the backpack but I read that carbon fiber ones aren’t good for this purpose, but I’m watching operators working with them.
I like a fishing rod of 6m, 12 segments, (57cms folded), 530grs. but it’s made of fiber carbon.
I watched another one of 7m (59cms folded) made of glass fiber, but it weights 1,7kg, and it’s triple price.
Is really noticeable the difference between a carbon fiber mast and a glass fiber one?
I have a 6m carbon fibre mast, the top sections are removed so it is about 5.3m effective. I used this with an EFHW in inverted L, i.e. wire runs up mast vertically about 4.5-5m then extends out. It’s not horizontal but slopes to a pole so the far end is about 1m AGL.
I do not run the wire close to the carbon mast but I do run it close to fibreglass masts. I also use a tuneable match unit so differences between the masts can be adjusted out.
Here is how I arrange the wire on the carbon mast, the wire was feint so it is picked out in yellow. This arrange minimises any effect the carbon mast has on the tuning.
It would probably work a bit better if the feed end was raised off the ground 1m or so.
EDIT: The mast came from Decathlon, Caperlan Lakeside 600 and is 40cm collapsed and weighs 322g. It says 1.8kg on it and that is the break strain when a fishing line is connected to the top.
A carbon fiber pole will detune the antenna if the wire wraps around it. Don’t do that. Have the wire go through a fishing pole tip-top or similar, then I simply use electrical tape to hold the wire at about the five foot level, then leave another four feet of wire dangling free and plug this directly into my impedance transformer, no feedline at all. If it is a resonant halfwave, no additional counter poise is needed.
I have been using a light weight (250 grams) pole for over 500 activations now. It is 17 sections and collapses to just 18 inches (half meter). It extends to about six meters. Have little concern about height when on a mountain peak. The antenna thinks it is very high if the ground drops away from it going down the hill. We have experimented just laying the wire on bushes a few feet in the air, still works fine.
Always lean the pole toward the wire. Do NOT try to support a centerfed dipole. Use very light weight wire, I use #28 teflon. I hold the end up with fishing braid, mere thread, but very strong, no stretch. I simply tie it to the wire using a nail knot, but if one simply must have an insulator, use a button.
I use a carbon mast for HF (incl. EFHW) without any negative effects (at least not that I have noticed).
For my VHF/UHF slim jim which runs vertical I use a fibreglass mast.
Richard (@G3CWI) did some videos on the topic which may be of interest.
I’m on my second 10M Spirit of the Air fibreglass pole, used with flowerpots with no problems have also used a Sotabeams Bandhopper with no problems with it. The reason I am on my second is the first one managed to snag at the base on some decking fence at a cabin, word of warning if these poles do break they have nasty glass fibre shards which make nasty cuts
I was a bit sceptical of Richards tests with the Carbon 6 mast, so last year I thought I’d try to see how much a HF vertical would be affected by running up a Carbon 6 mast. I made a simple groundplane for 17m with 3 sloping radials.
First I hung it from my glass fibre 6m mast and adjusted it for resonance. Then I swapped the GF mast for the Carbon 6 and re-swept the SWR. There was a big change as expected. So then I put the GF mast back and this time lent the Carbon 6 against it to simulate a wire antenna at 45deg to the carbon mast. Still found some detuning but much less:
You can’t go wrong with a carbon 6 from SOTAbeams. I regularly use my one with a W3EDP, EFHW or 41’ random. As for verticals, well I made a super short multiband vertical that works well with one. Can’t comment on de-tuning as I’ve only ever used non-resonant antennas with it (when arranged vertically that is).
I used a several poles from 4.1 to 10m , included carbon fiber and fiberglass in my sota activities.
Actually only use a 6m carbon fiber (Decathlon), if you don’t use as a vertical wire or something else the pole doesn’t detune the antena, tested with Rigexpert analizer.
The advantages of carbon fiber is not only the weight, the better think for me is that is more collapsible and little than others and you can put It into the backpack.
I use a SOTA beams carbon 6 usually to deploy my EFHW antenna inverted V style.
My tie off string is about 15 cm long so once the antenna is tied to the pole it is a short distance away from the pole. My insulator is a piece of flat zip tie with a hole through it big enough for the antenna radiating wire to freely slide along the wire so it can nestle into the right position at in the middle. I always put the pole up with the antenna wind ward side so the pole can bend and make sure the wire is freely pulling away from pole.
Seems to work OK with very little VSWR problems or difference on many activations and slightly different “lie of the land” scenarios pertaining to the summit environment at the time.
Regards
Ian vk5cz …
My SOTA antenna is a vertical, where the wire runs closely on the telescoping mast. My favorites are SOTAbeams Carbon 6 and Travel Mast (10m fiberglass).
The most important thing to minimize the carbon-related loss is not to allow the RF current to flow in the lossy conductor. One requirement is to keep the bottom of the carbon section well above the ground. In the case of SOTAbeams Carbon 6, the bottom section (the white, thickest section) is plain plastic, not carbon, so it is at least somewhat off the ground. I tend to mount the mast further above by tying it to a wooden or bamboo trekking pole when it is easy. I plan to make an elevated ground mounting tube out of PVC, but such an insulated mount will be even more effective with regular carbon fiber fishing rods where all sections are made from carbon fiber.
I also use elevated radials whenever practicable. I put the radial wires on top of bushes or low branches. It is best to keep everything off the ground and minimize the RF current flowing in the ground since the ground is a lossy dielectric.
I use PTFE or FEP jacketed wire (20 AWG) for the vertical radiator since it is slick and robust, so if it gets tangled with trees, a gentle pull is all I need to collect it. On the other hand, I use silicone jacketed wires (also 20 AWG) for radials since they are grippy, so minimum effort is needed to place elevated radials. I usually lay the wire on top of something, but the most I need is a half hitch, which stays in place for hours in the wind. I would never place silicone jacketed wires in areas where my arms cannot reach, as its grippy nature makes it difficult to collect when it gets tangled.
The photo shows Carbon 6 mounted on the ground directly, which places the feedpoint at the lowest position I’m ok with. I usually prefer higher (where a longer mast is convenient). This summit was bald and had only very sparse and isolated short bushes.
Correction: the bottom section of Carbon 6 seems carbon fiber. Testing for DC conductivity on the inside surfaces (e.g. the bottom thread) fails, but I revisited this by capacitive measurements. The bottom section behaves like a big capacitor plate, it’s just insulated on the surface. So, even Carbon 6 is best lifted from the ground.
I watched G3CWI video. His measurement setup for the “vertical antenna” is basically measuring permeability, which is irrelevant since carbon fiber is not magnetic.
G3CWI’s inverted V “test” is probably unaffected by the carbon mast because the midpoint of half-wavelength endfed is a current maximum and voltage minimum. If he used the carbon fiber to support an end of the radiator, the result may be more variable, depending on how the mast is used. (I’m not saying it is bad or cannot be done, I’m simply saying think carefully before doing.)
Here’s a photo of my carbon fiber fishing pole with an EFHW deployed in a very sloppy inverted V. It works fine. The wire is attached to the rod with a small plastic carabiner.
At home I’ll often use an aluminum painter’s pole in a similar configuration, but I attach a few inches of rope to the top of the pole and pull the wire slightly to the side to minimize capacitive coupling to the metal, and I elevate the ends of the wire to keep the wire nearly perpendicular to the pole, minimizing inductive coupling. That works well too.
Someone commented that the voltage is at a minimum near the middle of an EFHW antenna. That is only true when operating at the fundamental resonant frequency and odd harmonics. At even harmonics (e.g., operating at 20m using a wire tuned to 40m) there will be a voltage peak near the middle, so you do need to be a little careful about capacitive coupling. But the carbon fiber pole doesn’t seem to be conductive enough for that to be a problem and with the aluminum pole just a few inches spacing and a good insulator are sufficient.
Kirk, what you said may very well be true. With some spacing and crossing near perpendicularly, the wire and the mast have a few pF of capacitance and virtually no magnetic coupling. At voltage maximum that may still be detected as a small “de-tuning” although that is a different matter from a loss.
Another factor is the effect of having a “conductive” vertical element in the antenna field. The vertical polarization component of the sloper or inv-v antenna could interact and steer some directivity (somewhat similar to a vertical array, half square, or bobtail curtain but in a limited lossy way). That will be dependent on the mast length, whether the mast’s bottom is lifted or on the ground, and it’s going to be a simulator territory. The effect may just be a small perturbation in the radiation pattern.
In case of a vertical, those are not a problem, since the radiator and the mast experience virtually the same fields. It’s just that the bottom of the mast should be lifted well above the ground to prevent the loss.
There’s Ground and there’s ground. A damp grassy field will yield entirely different results to a shattered granite outcrop. Antenna modelling needs to be backed up with field work, which can often yield better results than antenna theory alone.
I know the ground difference. But the point I raised for carbon fiber supported verticals is different. It is the loss caused by the RF current from the feedline diverted away from the radiator downward. Any radiation from that portion will partially cancel the radiation from the radiator, and also being below the radial field and flowing toward the ground, there is no good effect. That’s why it’s good to lift the carbon mast off the ground.
I want to clarify that I don’t want to use wire vertical antenna. I want to deploy the wire antenna in slope, with an angle of 45º aprox when I use the 20m band antenna and a lower angle when I use the 40m band antenna (maybe try the Kirk’s solution inverted V). Isn’t my intention to deploy antenna vertical with the pole and with your advices I’ll avoid the contact between the fishing pole and the wire antenna.
The Declathlon fishing pole Lakeside 100 6m or 7m looks a fine solution for try myself and the price is a fraction cost of a fiberglass mast. I’ve looking for and I found the Decathlon store near my home has stock of both 6m and 7m. If in the future I decide change to a fiberglass one I always can go to fish with the carbon fiber pole.
I use a 7m Goture telescoping Tenkara pole with one or two top sections removed and this little clip holding the wire. It works great. Both came from Amazon.
