I'm making an antenna and have a question

Wulfshead
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I'm making an antenna and have a question

Post by Wulfshead »

OK, I'm making a 1/4 wave ground plane antenna for 2 meter and want to make it sturdy for our windy UK.
I ordered the chassis but would like your thoughts on what I would like to do.

I did the maths @ 145.0 MHz and came up with plane lengths of 19.35 inches (which I worked out was approx 19 & 3/8 inches)
So, what I need to know is this, if I place the copper wire planes centrally in plastic or wooden washers/spacers of 5mm x 18mm (3 per plane) and then slide the centrally suspended planes inside 20mm plastic overflow plumbing pipe would that adversely effect the performance of the TX/RX ?
If it does not I intend to seal the ends of each plastic pipe with a correct plastic plumbing cap.
Where the 5 planes meet the chassis I intend to use an outside weatherproof plastic electrical junction box with 4 knock out holes (20mm dia) and drill one for the vertical plane in the top.
I intend to fix the planes tight with water tank plastic quick fit tank pipe screw fittings.
The plastic weatherproof box that will form the cover for the termination of the radials on the chassis is circa 3 inch x 3 inch x 3 inch.

I hope it'll work as I've spent most of today working out the design, stripping wire and finding where I can buy the bits or buying bits. :lol:

Thanks in advance for your thoughts.

Wulfshead
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Arzosah
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Re: I'm making an antenna and have a question

Post by Arzosah »

Absolutely no thoughts at all about this, sorry :oops: I'm just in awe at the level of technical ability :) I hope someone can answer your query!
Wulfshead
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Location: Area 4

Re: I'm making an antenna and have a question

Post by Wulfshead »

Arzosah,
back in the early 80's I had a pre-programmed illegal AM CB which needed little or no technical knowledge to get up and running.
What knowledge that I have that may have imparted awe is directly due to the members here who inspire me and point me, and others, in the direction of much needed study.
It is credit to both this site and the comms savvy members upon this site that an old bugger like me has rekindled his interest in comms, for that, come the SHTF, I shall be VERY thankful :D

Wulfshead
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munchh
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Re: I'm making an antenna and have a question

Post by munchh »

Im just off to bed and only on my tablet, all my good info is on my pc, I will have a hunt for a few pdfs, have a search on line for antenna calculators, they are really handy.

most of the 1/4 waves I have made are either for small mag mounts or usong a surface mount pl plug with a peice of thick wire the correct length in the centre an a radial on each corner, coax dipoles are quite handy, have a look for a thing called a "hentenna" its made from copper plummers pipe, I was blows away forst time we tried one.

I was always told putting anything inside a tube is not as good as the metal in the air, but that could be wrong, I dare say a few of the better informed fellows will be along before I wake up, but I will dig some bits out for you.

its always great to talk on one you made :ugeek:
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munchh
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Re: I'm making an antenna and have a question

Post by munchh »

P.S.
my 5/8 wave antennas are definatly the best and are very cheap for 2m.
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I'm not antisocial, just anti idiot.
If you use the phase "man up" you have alot to learn.
"Wise men speak because they have something to say, fools, because they have to say something" Plato.
Hamradioop
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Re: I'm making an antenna and have a question

Post by Hamradioop »

Hi Wulfshead,

The measurements look good to me and the use of plastic conduit will be fine if you use White Plastic. Black Plastic can contain carbon which will adversely affect the Standing Wave Ratio of the antenna.

For further research I would suggest a Slim jim J pole. To give you a head start read here http://www.hamuniverse.com/slimjim.html. and the orignal notes by the designer here http://www.hamuniverse.com/g2bcxslimjimantenna.html

for a roll up version have a look here http://www.freewebs.com/wacral/Build%20 ... e%202m.pdf
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Wulfshead
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Re: I'm making an antenna and have a question

Post by Wulfshead »

Thanks Munchh & Hamradioop,

These little UV-5R radios are quite good and real bait to get you into the radio thing again.
I often now chat to my 88 year old dad about the amateur radio stuff I come across on-line and in links.
My dad likes to remind me that when he was in his 20's the equipment to do what was needed would take up most the wall space in the average 3 bedroom boxroom.
Obviously these little radios wont go world wide but they give you that push to want more watts and better equipment, I can really see my injury compensation taking a bashing after January when I do my foundation licence :lol:

Munchh,
Any info on antennas is always welcome

Wulfshead
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munchh
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Re: I'm making an antenna and have a question

Post by munchh »

Mornin, are yes the j-pole, we made some out of that ladder roleup stuff, goot for backpacking, you just reminded me I have a closed jpole for going on a pole in my shed :D
Have you looked to see if there are any echolinks near you, I spoke to a guy in Australia while driving up the A23 once on a handy in my car, that was fun.
AREA 3
I'm not antisocial, just anti idiot.
If you use the phase "man up" you have alot to learn.
"Wise men speak because they have something to say, fools, because they have to say something" Plato.