Author Topic: Antenna design  (Read 3010 times)

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Offline northdublin

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Antenna design
« on: May 04, 2014, 01:28:30 AM »
i have just made a 3 element beam for 11mtrs by copying a gizmotchy design.
is there a way of downsizing the design of this antenna for use on a field day or in a location where you might not be able to install a full size beam. going by the specs it looks like its a 1/4 wave, could i posibly make a 1/8th wave version with any success.
this the antenna in question

kenwood ts 870
Yaesu ft-857
sirio gainmaster
inverted vee
chameleon ch v1

Offline vanmie

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Re: Antenna design
« Reply #1 on: May 04, 2014, 15:38:56 PM »
changing this design will be very hard, or next to impossible, and maintain the characteristics of the design and performance.

If you are looking to build an antenna for a field day; you may look to build a hex-beam for the band(s) you want.
A Hex-beam is a 2 element, with a very small foot print, and an excellent F/B ratio

you would probably want the use of an antenna analyser for the pruning and tuning at the final stage of your build.

Google it, there are many designs on the internet, maybe not for 11 meters, but you can adapt the wire lengths.

HTH,
Edwin.

Scanner: UBC-3500XLT, UBC-355CLT, GRECOM PSR-255
PMR446: Binatone A-950
HT's: Wouxun KG-UVD1P/KG-669P, Puxing 777-Plus, Baofeng UV5-RE
TX: Kenwood TS-570DGE, Icom IC-7000, Sommerkamp FT-767, Yaesu FT-101ZD, Kenwood TM-D710E, Baojie BJ-9900
Antenna's: **lots**

Offline freecb

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Re: Antenna design
« Reply #2 on: May 04, 2014, 17:28:10 PM »
Google it, there are many designs on the internet, maybe not for 11 meters, but you can adapt the wire lengths.

HTH,
Edwin.

clearly its wanted for the 11 meter band so thanks for your not so input,,,sometime i wonder in this world,,we can all say google it
go on Bertie bud

Offline vanmie

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Re: Antenna design
« Reply #3 on: May 04, 2014, 17:34:24 PM »
clearly its wanted for the 11 meter band so thanks for your not so input,,,sometime i wonder in this world,,we can all say google it

actually; after a Google, I found a quote from Steve who designs and manufactures hex beams for a living

Quote
Take the dimensions published for 10m and multiply by 1.036

73,
Steve G3TXQ
source: https://groups.yahoo.com/neo/groups/hex-beam/conversations/topics/7637

so, take one of the G3TXQ designs and make a single band hex beam.
I don't see why you would classify my advice/response as a "not so input" ... a hex would get you a simple 2 element field antenna with a small foot print... exactly what the OP asked for !

Rgds,
Edwin.

Scanner: UBC-3500XLT, UBC-355CLT, GRECOM PSR-255
PMR446: Binatone A-950
HT's: Wouxun KG-UVD1P/KG-669P, Puxing 777-Plus, Baofeng UV5-RE
TX: Kenwood TS-570DGE, Icom IC-7000, Sommerkamp FT-767, Yaesu FT-101ZD, Kenwood TM-D710E, Baojie BJ-9900
Antenna's: **lots**

Offline vanmie

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Re: Antenna design
« Reply #4 on: May 04, 2014, 17:53:44 PM »
another design for an 11 m hex: http://www.dx-antennas.com/HexBeam.htm

I think I googled enough today...

Scanner: UBC-3500XLT, UBC-355CLT, GRECOM PSR-255
PMR446: Binatone A-950
HT's: Wouxun KG-UVD1P/KG-669P, Puxing 777-Plus, Baofeng UV5-RE
TX: Kenwood TS-570DGE, Icom IC-7000, Sommerkamp FT-767, Yaesu FT-101ZD, Kenwood TM-D710E, Baojie BJ-9900
Antenna's: **lots**

Offline northdublin

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Re: Antenna design
« Reply #5 on: May 04, 2014, 23:24:15 PM »
Thanks for the replys lads.
the lenght of the elements on the gizmotchy would suggest to me its a 1/4 wave, would i be able to make a similar antenna in a 1/8th wave.
i have also made a v quad recently and i could adapt/ rebuild it to make it more portable but i like the idea of having vertical and a flat side in one antenna.
i do need to get my hands on a analyser because even though i have the swr right down i do need to check it propperly.
kenwood ts 870
Yaesu ft-857
sirio gainmaster
inverted vee
chameleon ch v1

Offline martins

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Re: Antenna design
« Reply #6 on: May 07, 2014, 12:23:04 PM »
if you're building it 1/8 wave, it will be really difficult to match it, basically it will have somewhere around 10-13 ohm impedance, that means for every 5W leaving your radio only 1W will exit the antenna. To match it, you will need a balun, but I can't think of a simple design that would address it.

Anyhow by downsizing the antenna you will loose all its characteristics and will likely be better off with a whip on a roof of a car

Offline northdublin

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Re: Antenna design
« Reply #7 on: May 07, 2014, 18:59:55 PM »
thanks for the info, we usually bring poles and an 11mtr vertical like the imax for the field stuff but i thought it might be interesting to try a compact beam.
The beam i have made could also be broken down and transported easilly so thats an option too.
kenwood ts 870
Yaesu ft-857
sirio gainmaster
inverted vee
chameleon ch v1

Offline martins

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Re: Antenna design
« Reply #8 on: May 08, 2014, 00:26:59 AM »
where did you get supplies for your beam? I'm looking to build something for myself but can't find any stores that would sell aluminium pipes

Offline northdublin

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Re: Antenna design
« Reply #9 on: May 08, 2014, 16:36:25 PM »
healy steel, 01-4194000.
http://www.jameshealy.ie/
Very nice people to deal with and they cut on site.
kenwood ts 870
Yaesu ft-857
sirio gainmaster
inverted vee
chameleon ch v1

Offline martins

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Re: Antenna design
« Reply #10 on: May 09, 2014, 12:23:46 PM »
thanks, I'll give them a shot once I decide on a design

Offline northdublin

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Re: Antenna design
« Reply #11 on: May 10, 2014, 01:42:00 AM »
No bother.
When buying your hardware, maybe try all metal fasteners and tucks fasteners.
They have pretty much all you would need and at a fraction of the cost compared to some of the diy outlets.
kenwood ts 870
Yaesu ft-857
sirio gainmaster
inverted vee
chameleon ch v1

Offline eiei0

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Re: Antenna design
« Reply #12 on: May 10, 2014, 16:03:27 PM »
It's hard to tell if you have an attitude problem or maybe your foreign ???

Either way if you don't have anything positive to say then maybe say nothing,


Google it, there are many designs on the internet, maybe not for 11 meters, but you can adapt the wire lengths.

HTH,
Edwin.

clearly its wanted for the 11 meter band so thanks for your not so input,,,sometime i wonder in this world,,we can all say google it
Royal Discone-EcoFlex10-UBC780XLT

Offline martins

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Re: Antenna design
« Reply #13 on: May 10, 2014, 20:13:09 PM »
or maybe your foreign ???

I'm also an "import", had a great laugh how you put the same weight on "having an attitude problem" and "being foreign" :D :D :D

Offline eiei0

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Re: Antenna design
« Reply #14 on: May 11, 2014, 00:14:59 AM »
No offence meant to foreign people but some can be abrupt and very straight to the point,
Where some of us Irish are just a holes and nit pick everything people say,


 
or maybe your foreign ???

I'm also an "import", had a great laugh how you put the same weight on "having an attitude problem" and "being foreign" :D :D :D
Royal Discone-EcoFlex10-UBC780XLT