Copper Talk » Open Forum » Archived Messages » 2002 » 09/01/2002 to 09/30/2002 » Building A MURS 5/8 wave Antenna? « Previous Next »

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Chris Hughes
Posted on Friday, September 13, 2002 - 8:46 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)
I've been building MURS beams and 1/4 wave ground plains for a while now with great success and would now like to know if any one would have any ideas on a base 5/8 wave vertical antenna for the MURS band in the 151 MEG range.
The standard formula I'm using for the 5/8 wave is , 585 divided by the freq of 151MHz which comes to 3.87 feet for the vertical lenght. This formula is for a wire antenna. Here is where I could use the help. In order to make this work right, one needs to add a coil to get the SWR correct I understand. Ok, so what size of coil and gauge of copper wire to use?
I have built one all ready and guessed on the coil lenght and size as well as the gauge of wire, the swr's are a 1.1 but my 1/4 wave base antenna out talks it according to my contacts. So something can't be right!

Have any of you built any 5/8 wave antennas for 2 meter or murs? If so got any ideas for me?
If you have something on the 2 meter 5/8 wave, I don't see why I couldn't just trim it a bit.

Yea I'm sure I could just by one, but where's the fun in that.....LOL!
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bruce
Posted on Saturday, September 14, 2002 - 4:32 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)
Chris yes you can trim a 2 meter 5/8 amd it will work just fine
What i found works nicely is a 5/8 wip loaded to 3/4 wave with a small coil so it looks close to 50 ohm with no taps just pulg and play.


45.8 for the wip and 9 inches for the coil ( come off the bottom of the wip in a nice laze loop back to the center pin 1 or 2 turns ) use stiff wire to cut protype and as soon as you have swr where you want it a 50 inch stanless wip cut with a bent copper wire should do it

Look at the ARRL books and Bill Orr's books lots of ideas
Bruce
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bruce
Posted on Saturday, September 14, 2002 - 8:39 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)
O one more thing 5/8 wave antennas needs a groundplane Think about one of the J-poles I had very good luck with them on 6, 2, 220 and even 440 mhz they are very simple to build and work as well as a 5/8 wave

http://www.packetradio.com/jpol.htm