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#11
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do I have my antenna fundamentals right?
On Tue, 16 Jan 2007 09:16:30 -0500, Bud wrote:
Not sure where you are, check to see if there are any nets on the repeaters in the area Near Fort Worth. 73's Richard Clark, KB7QHC |
#12
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do I have my antenna fundamentals right?
MK, this diagram is fantastic! I guess I should have explained to all
of you that as a college student I have more time than money, so it may be a while before I can even afford the PVC and wire. I bet it will outperform my mobile-dipole-on-a-stick, though! Nelson On Jan 16, 10:22 am, wrote: markus wrote: hi Nelson, yes, it is a lot of work, you could just attach the magmount to any metal object, patio table, metal railing or window a/c unit, etc.Yea, I suppose you could... Arf.... :/ or for a few dollars and less work build a great 2m antenna using #12 thhn wire and a few feet of pvc pipe.With even less work and $$$, he could just build a ground plane using 5 wires and a so-239 or whatever.. this is the half square, works great, it is directional.Probably not what he wants for 2 meters, unless he can steer the pattern. http://cebik.com/vhf/hs.html then you can try this one, the Moxon for 2m, little harder to make but has similar gain to a 2 element yagi in less space and direct fed with 50 ohm coax (like the half square is fed).Antennas are small on 2m.. He could live a little and use 3 elements and have a good bit more gain. But then he has to rotate the thing.. I recommend a easy 1/4 wave ground plane to start. It will work about as well or better as any of the other "easy" vertical whips for 2 meters. Attaching a 2 meter whip to a railing, table, AC unit , etc is going to function in a fairly poor manner. The ground radials need to be resonant to function properly. Would be much better to use 4 simple quarter wave radials. You can slope them down at about 45 degrees to get a better match, and maybe a tiny bit more gain. MK |
#13
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do I have my antenna fundamentals right?
Richard Clark wrote:
On Tue, 16 Jan 2007 09:16:30 -0500, Bud wrote: Not sure where you are, check to see if there are any nets on the repeaters in the area Near Fort Worth. 73's Richard Clark, KB7QHC Richard; Go to the following URL: http://www.artscipub.com/repeaters/ click on Texas and search for "Fort Worth". You should get two pages of both VHF and UHF repeaters. Dave WD9BDZ |
#14
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do I have my antenna fundamentals right?
Nelson Blaha wrote: MK, this diagram is fantastic! I guess I should have explained to all of you that as a college student I have more time than money, so it may be a while before I can even afford the PVC and wire. I bet it will outperform my mobile-dipole-on-a-stick, though! Someone else posted that.. Myself, I wouldn't use one of those on 2m. Sure, it would work, but for about the same or less amount of work you could have a small 3 el yagi. I would not use a directional antenna unless you had an easy way to turn it. A ground plane is super cheap, and will do just fine. You can place them on a mast, hang them from ceilings, etc. I've got a ground plane hung in my attic for emergency use. With 2m FM, gain is not really that important. Decoupling from the feedline is though. The decoupling with the GP will be fairly decent. If you use an off size "counterpoise" to mount a whip on, it's not resonant, and generally will do a poor job vs a complete antenna. You will find in most cases like that, the decoupling from the feedline will be poor too. I'd start with a simple 1/4 wave ground plane, and go from there. All you need is a SO-239 and 5 pieces of wire about 19-20 inches long. Most bend the lower ground radials down at about 45 degrees to get a better match to 50 ohms. You can set one on a table unless the coax is thick... :/ Can't get much cheaper than that, and it will work well. To me, the half square is too much work, too little gain for 2m.. Good for HF tho.. A 3 el yagi would clobber that thing on 2m, and isn't too much bigger.. MK |
#15
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do I have my antenna fundamentals right?
"Nelson Blaha" wrote in message ps.com... Having gotten some help around here on how to power my 2m mobile indoors cheaply, I need to figure out a way to get an antenna. There are probably a million holes in this plan, please point them all out to me! I intend to get a piece of square sheet metal (ground plane?) about half a meter each way, and build a bracket to hold it outside my window horizontally. In the center of the sheet metal I'll install an NMO mount for my mobile antenna. I'm actually planning to ground the sheet metal using the electrical ground in the wall socket (surely something's wrong with THAT!) I look forward to better alternatives! IF I were working off a balcony I would use a Yagi or maybe a quad sense the building will be blocking the signal in at one direction any way. I used to hace a two element quad I made on a broom. I would sit on the balcony and hold the quad in one hand and my HT in the other. BAd thing is that now there is now way to hold the beer. |
#16
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do I have my antenna fundamentals right?
You could go to your local Radio Shack and look for a scanner antenna. They
have a small vertical with 3 eleament ground radials. I bought one for $11 in the bargin bin for a new ham in my area.. You can even use it to transmit on 2meter band (after your legal) Joe KI4ILB I intend to get a piece of square sheet metal (ground plane?) about half a meter each way, and build a bracket to hold it outside my window horizontally. In the center of the sheet metal I'll install an NMO mount for my mobile antenna. I'm actually planning to ground the sheet metal using the electrical ground in the wall socket (surely something's wrong with THAT!) I look forward to better alternatives! IF I were working off a balcony I would use a Yagi or maybe a quad sense the building will be blocking the signal in at one direction any way. I used to hace a two element quad I made on a broom. I would sit on the balcony and hold the quad in one hand and my HT in the other. BAd thing is that now there is now way to hold the beer. |
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