| Author |
Message |
    
ncrebel unit 168
| | Posted on Friday, January 18, 2002 - 1:32 pm: | 
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Hey,I have a question regarding scanner antennas.
First of all,I have read where I can make a scanner antenna out of wire.Just hook the wire to a BNC connector etc.Well,my question is is if you can use insulated wire to make an antenna with.
Would the antenna still receive like it should with the insulation on?I'm fully aware that different size antenna work better for different
freq's.I just need to know if the insulation around the wire would cause any problems.
Thanks |
bruce
| | Posted on Friday, January 18, 2002 - 2:24 pm: |
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your radio will not care if the wire is covered or not however you must make contact with the center pin of the connector so it has to be clean at that point. As for size a 19 in long wire will work on BOTH the 150mhz and 450mhz bands a 54 inch wire will work on the 50mhz and 150mhz bands if you are looking to hear trunking (800mhz) you need a 4 inch wire 2770/frequency will give you about 1/4 wave which is what you need |
Znut
| | Posted on Friday, January 18, 2002 - 7:40 pm: |
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Hello, this is my first posting. Bruce is right on. I would like to add that a J-pole would be an excellent base antenna. A 2 meter j-pole will receive most VHF & UHF frequencies fairly well and you can make it with copper tubing. Since you won't be transmitting, you do not have tune the feed point of the antenna too critically (no swr meter necessary). Check packetradio.com for some good info!
Take care, Randy |
bruce
| | Posted on Friday, January 18, 2002 - 8:21 pm: |
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znut I love Jpoles they are like a volkswagen you tunn them up put them up and 20 years later they are still there mine for 6 meters lasted almost 25. As for swr they are forgiving over the 2 meter band the ones ive used on 2 and 6 meters will cover the band with a less than 1.7 : 1 match tha ARRL handbook and antenna books cover them as does the willam orr antenna books that W5YI carry now if you want very wide coverage a discone is the way to go radio shack makes a very good one it is not cheep but mine has less than a 1.8:1 match on 6, 2, 220 and 400 ham bands and it is about 5 foot tall. |
Znut
| | Posted on Saturday, January 19, 2002 - 11:11 am: |
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One of those discone antennas would be ideal for scanner use, the omnidirectional equiv. of a L.P. OH, I think I got to idealistic for ncrebel, he did ask about home made ones, sorry rebel. I have made a 2 meter ground plane with some housewire and some metal rods, angled about 45 degress for the GP. It resonates on several frequencies (145mhz and up). Use the length bruce suggested for the vertical element. About an inch longer for the radials, this seems to help broaden the bandwith some. If you can, go the extra and make a j-pole. There is a webpage out there with one called a copper cactus, all it is is seperate antennas(j-poles) for different freqs, stacked largest to smallest, bottom to top. Each fed with its own coax(RG 316 or something small, I'm sure). I think one tuned to 145mhz or so would be fine for receive-only use, up to 900mhz or so. If you have the money and space (about 3-times) a 6 meter one would be neat, however, I don't know how the receive would be at 800 - 900 mhz. Maybe we could talk bruce into hooking his (6 meter j-pole) up to a scanner or analyzer and letting us know!
Take care, Randy
P.S. try www.cvarc.org/jpolescl.htm for a pocket (roll-up wire) j-pole for cheap, portable use! |
ncrebel
| | Posted on Saturday, January 19, 2002 - 5:28 pm: |
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Hey thanks for the replys.
*Unit 168 "Timberwolf"*
Eastern North Carolina |
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