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yes, an analyzer will be needed ..but i had an idea... i could design it for any frequency and scale it up or down ...so if i had 2 telescopic antennae, you can buy pretty big ones or have some ally tubing with a lot of adjustment and set the length for 5/8 wave for whatever frequency, feed...

not really sure why you posted this here ...i am asking about the design of a vertical antenna but looks like a good antenna and deserves to be posted someplace

no ..use hose clips ..good quilty preferably stainless and cover with good quality electrical tape

i understand that but if i was to design a vertical OCF 5/8th wave how would i determine the feed point?

I was researching the Shakespeare big sticks for some unknown reason and as i have been amassing materials to make an aluminum 17M vertical dipole .. a dipole was chosen as no radials are needed and simple construction with the coax going up inside the ally tube feeding the center and no...

having just read all this thread i would like to point some things out things 1 if the antenna is shorter it should still work just as well for 11m when it comes to SWR as the manufacturer will have (or should have) adjusted the value of the components in the matching device to compensate...

here on the lincolnshire coast we just got rain and then some more ....its still raining

i see so is a type of j pole ...so what's the idea of the extended pole below the feed point and the radials ?

this was posted on my FB page i will cut and paste my FB reply which abit of a description and my thoughts but you need to see the photos in the link to the original article below but what i am asking what type of antenna is it and how do it work any links to articles about this antenna would...

sooo will having the feed point viar the gamer match being in a different place change the charastics of the antenna? ..A normal j-pole i bleve is a 1/2 wave and the 1/4 wave U is used for matching and the 2 parallel 1/4 wave bits sort of cancel each other out like ladder line feeder do...

now it was a little time ago when i came to this conclusion so i hope i not forget i was modeling 5/8 wave with 4 radials using manma software (much easier than NEC) just playing with the length of the radiator till i had best gain at a low angle which ended up very slightly longer than 5/8...

better photo from that link

link to manufacturer https://radio-media-system.com/epages/box6392.mobile/sec9c8e079d1e/?ObjectPath=%2FShops%2Fbox6392%2FProducts%2FITAINTER27&fbclid=IwAR2EUV-iW782z1hOAuuUNaB5vaF4rT1-52J4Ttl_AgDqK2DZnO3ztTrqaew

i see a photo of a 27mhz j-pole sold by a French company and in the photos it seems to have a gamma match....so i assume its no longer a J-pole i believe a J-pole is a end fed 1/2 wave with a 1/4 wave matching stub and behaves much like a 1/2 wave so if it fed with a gamermatch will it work...

I am a bit puzzled ..the Sirio Megawatt 4000 is a 11m mobile antenna ..its 6feet 6inch long and base loaded ..however, Sirio gives it out as a 7/8 wave ,, well i know a 1/4 wave don't need a matching device and a 7/8 wave will need one ..but the Sirio don't need one which would lead me to...

then you have to divide by 2 again as rf amps are only about 50% efficient ...1/2 of the power is heat hence the big heat sink ...so about 225w

i will have to read that sevral times ..more photos here http://www.radiomanual.info/schemi/ACC_antenna/Solarcon_A-99_review.pdf

Solarcon say the "A99 is a half wave over a quarter wave variable mutual transductance tuned antenna" i understand the variable mutual transductance bit,, that will be the tuning rings over the inductors i know its not a 1/2 wave physically over a real 1/4 wave as it will make it 9feet longer...

i just check mine its 105.5 from top of hoop to the center of the bolt ..pretty certain its with in 1/2 an inch of original when i fixed it

Looks good up their ..how high is it ? the weak point seams the ring attachment to the radals ,,on mine the way sirio had crimp the end of the tube flat thay had crimpt it way to hard and flat so i believe it has over work hardened it you can see below its splits at the side and has left a mark...