The "Fat Max" antenna

Densil wrote:
not sure what paracord is

Here's the paracord

https://en.wikipedia.org/wiki/Parachute_cord

it's relatively cheap and can be easily found on Amazon, I used and use it regularly and found it to be perfect to hold up antennas

its also so light i am shure it can be dragged using the crossbow tied to an arrow (one of my hobbies).

My suggestion, to throw a rope through a tree (branch) is to buy a so-called "arborist line" (throwline), here's an example

https://www.buxtons.net/arborist/tree-climbing-gear/throwlines

it's made so that it won't remain locked onto the branches and will easily slide; one throws it up the branches, then tie the support rope (or paracord if you'll use it) to the line and pull it so that the rope will pass over the branch, at that point it will be easy to tie the antenna wire to the rope (a bowline knot will be ok for that) and raise it; my suggestion is to start by fixing the antenna wire at the house end using a piece of rope so that the wire will be at about 20 to 50 cm (or more) away from the wall, then pass the rope over the tree branch and, again, pull the rope until the antenna wire is 20 to 50 cm (or more) away from the tree, if the antenna wire is longer than available space, just let it drop down vertically (keep it at least 2m from ground though); do NOT lock the end of the rope but instead tie it to a weight, this way if wind/ice or a falling branch "load" the wire, the rope will slide but the antenna wire won't break

Hi Densil,
thin cords and ropes made for yachting may be better to make fixed installations outside. Their outer layer is made of polypropylene, which is highly UV, rain and weather resistant (more than nylon). They are lightweight, as they are expected to float on water. They are made in various colours cca 3 mm dia and more. Seek your boating shop or hobby market.

I would recommend to shoot a nylon fishing line (monofilar) using a crossbow. Then use this line to pull the cord/rope up.

VBR from Ivan

Andrew wrote:use some weight to throw a rope over the tree (a spool of paracord won't break the bank and will serve you well), then use the rope to hang a run of insulated wire between the roof and the tree; for the remainder... see my other post in the forum

35 ft of wire will get you on air 40...10 meters, not bad

Hi andrew. thanks a lot for the info. that is abt what i was thinking. not sure what paracord is but it must be the same as "byggtråd" or the stuff builders use to mark out land. that is made of nylon and it can stand many kg. its also so light i am shure it can be dragged using the crossbow tied to an arrow (one of my hobbies).

i will give it a try and see if it is visible. i will search for your other posts, altough i may have read most of them but now a little more thorough.

Thanks for all your advise.
/D

use some weight to throw a rope over the tree (a spool of paracord won't break the bank and will serve you well), then use the rope to hang a run of insulated wire between the roof and the tree; for the remainder... see my other post in the forum

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35 ft of wire will get you on air 40...10 meters, not bad

Hi andrew.
I saw the link and the length chart. that is what got my interest - and ur description. i now live in an apartment 3rd floor of 4. my mancave has a window at the back about 10m from a big bushy tree. sycamore i think. lots of leaved in the summer but now bare.
my thought was to throw a rock over the 12m high tree to pull some thin enameled wire over it then i can control the length but not the route or coupling into the tree. i have some transformer wire abt 1mm round so i can have 10m down to the tree top and 15m over the tree = 26m.
Plastic covered wires always visible so i want to avoid that otherwise the neighbors will complain to the kommun as they have already done a few times
As a counterpoise i could drop more magnetwire to the ground out of the window and even bind it to the heater element under the window. i will also have to regulate the pwr to just a few watts, mebe only 25w max
ok on the slinky. mine has rusted and dont use it now and new slinkys are made of plastic.
i would not get a fat max there without someone seeing it and any feeder would be a dead give away.
Like ivan and harry keep saying - try it.

br /D

Densil wrote:Hi andrew nice to chat with u for the first time.
Harry and ivan discused a variable length antenna using spools abt 6 months ago. harry said it could be 1 of his winter antenna projects.

I know, that's one of the reasons why I decided to post the link to that "meter antenna" idea, it may be useful and/or suggests ideas to Harry

I was interested in the random ant you wrote abt in a prev post - i followed some of harrys ant projects. i have neighbors that dont like me putting up antennas. can you use magnet wire? does it have to be isolated from trees?

The random is a simple antenna with low "visual impact", so may be tolerated by your neighbours, especially if you use some relatively thin wire (say 1.5 to 2.5 mm diameter) with a neutral color (external insulator), as for the lenght check this reference card 

https://udel.edu/~mm/ham/randomWire/

and consider that a wire of about 26m with a decent counterpoise will allow you to cover all bands from 80 to 10 meters, then just pick the longest wire fitting your available space from the above table; but for a detailed discussion about installation, please open a new topic

the fat max can this be related to the slinky antenna? I tried that (the slinky) many years ago and it was great with a really wide bw. covered all the hf bands with an atu but didnt need one for 40 and 30. swr under 1.5 on lower bands. i didnt try changing the length - fixed length - because it doesnt change the wire length.

I've to say that I don't like the "slinky", sure it will work, but I'd rather use another antenna, and sincerely I won't compare the slinky to the "fat max", also since the latter may be improved, while ...  there's little to do with the slinky, then for sure, anything goes if you are in an emergency or can't put up something better

Q. if u use measuring tape in an ant then they are a coil inside ok with just paint an ink - can that isolation break down with high rf power? like over 10w? my feelings is that it would be great for rx or qrp and /p.

asked the same question to Martin and he told me that, while the coiled tape does indeed affect the antenna, since you can adjust the extended lenght it isn't an issue

Hi andrew nice to chat with u for the first time.
Harry and ivan discused a variable length antenna using spools abt 6 months ago. harry said it could be 1 of his winter antenna projects.
I was interested in the random ant you wrote abt in a prev post - i followed some of harrys ant projects. i have neighbors that dont like me putting up antennas. can you use magnet wire? does it have to be isolated from trees?

the fat max can this be related to the slinky antenna? I tried that (the slinky) many years ago and it was great with a really wide bw. covered all the hf bands with an atu but didnt need one for 40 and 30. swr under 1.5 on lower bands. i didnt try changing the length - fixed length - because it doesnt change the wire length.

Q. if u use measuring tape in an ant then they are a coil inside ok with just paint an ink - can that isolation break down with high rf power? like over 10w? my feelings is that it would be great for rx or qrp and /p.

/D

The author (Martin, G8JNJ) also calls it "a poor man Steppir antenna"; it's made using a 10m measure tape which is extended or retracted to bring the antenna to resonance

https://webzoom.freewebs.com/g8jnj/FatMax%20Antenna.pdf

the author states that the antenna will work from 40 to 6 meters, but also offers some idea to bring it down to 80m

Willing to make it stealth, after enclosing it inside a pipe painted with some neutral color you may add a weather vane at its top

As for improving it, it may be possible to replace the steel measuring tape with some 3d printed spool with a winding coil and use copper wire, also, to bring it down in frequency, it could be possible to add a coil (at bottom, inside the pipe) instead ou using the loosely coupled cap hat suggested in the pdf

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orienting the radials toward n/s/e/w (and intermediate directions) and using the wind indicator at top will also allow to disguise the real radials purpose

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the coax feeder may either be buried or left on ground, in either case say to curious people that it's used to connect the "wind indicator" to your homebuilt weather station !!