took my bird over to buddy of mine to check swr with it will i put a 10w slug into it and 1 and 40 should 4 watt dk, but when i rolled to the reflect was 0 on both. no trees or power lines truck running, doors closed,ac on,am-fm radio.any body ever see that and if so what doe it mean. on my setup it dk at 3 and refl. at .1 or .2 but not 0. i put my dorsy on and it read 1.0 on both 1 and 40.
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swr?
- Thread starter bigboy250
- Start date
Your antenna is probably working a bit better than your buddies in doing what it should do. A 1/4 wave antenna shows a natural end-impedance of about 38 ohms and this will produce a SWR match of about 1.3 when the radiator and the ground plane are in good order. It is hard to tell what the ground plane is in a mobile. So if your full length 1/4 antenna is showing a lower than 1.3, and if you are able to improve the GP somehow, you will likely see a little increase in the SWR and that is good, not bad like most folks think.
Shorter mobiles typically use a small coil to help improve the match of a shortened antenna and it can also be done to make the match show a perfect match at the radio and that is good for their business and your radio, but it is a compromise and to accomplish this low SWR reading the antenna losses are basically being increased a little bit. We're not talking about much so it is not a worry, you won't even be able to measure or detect it in operations probably.
Again, there is not much difference in results so I would not worry about either of your setups as long as the TX/RX seems to be doing OK.
If both you guys just want to test your rigs a little more and get a better understanding, then get you a cheap Field Strength meter that will respond to your mobile antennas, figure out what it does, and then set up your mobiles in a way that you can compare signals that way. There may be enough difference in a lossy SWR reading and one that is not to see the difference on a FSM.
Good luck.
Shorter mobiles typically use a small coil to help improve the match of a shortened antenna and it can also be done to make the match show a perfect match at the radio and that is good for their business and your radio, but it is a compromise and to accomplish this low SWR reading the antenna losses are basically being increased a little bit. We're not talking about much so it is not a worry, you won't even be able to measure or detect it in operations probably.
Again, there is not much difference in results so I would not worry about either of your setups as long as the TX/RX seems to be doing OK.
If both you guys just want to test your rigs a little more and get a better understanding, then get you a cheap Field Strength meter that will respond to your mobile antennas, figure out what it does, and then set up your mobiles in a way that you can compare signals that way. There may be enough difference in a lossy SWR reading and one that is not to see the difference on a FSM.
Good luck.
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With the FSM idea, do NOT touch the meter when taking readings. In fact, don't be anywhere within at least 50 feet of it. They are extremely sensitive to anything within a good-sized radius: people, animals, trees (unless it's a windless day).
The few times I've used an FSM, I set it up on a tree stump about 100 feet away and used some good binoculars to read the meter. Frankly, it was wasted time, but since I learned that, it wasn't an absolute waste :drool: .
I'd ask a third party a mile or more away to observe, compare and report the results.
The few times I've used an FSM, I set it up on a tree stump about 100 feet away and used some good binoculars to read the meter. Frankly, it was wasted time, but since I learned that, it wasn't an absolute waste :drool: .
I'd ask a third party a mile or more away to observe, compare and report the results.