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Transmit pattern

I have learned through practice with a Rig Expert, that super low SWR does not necessarily mean a super efficient antenna. I tune for resonance near the middle of the band and the SWR is not always minimal, but the reactance values are very low. Watching the amount of reflected power on voice peaks tells me most of the power is going to the antenna, hopefully being radiated. And this is with antennas in less than optimum locations/situations. IMO, SWR is not the most important factor and an antenna can be an efficient radiator with a SWR from 1.5:1 or higher up to 2:1, if the reactance values are as close to resonance as possible.

And so far, I've not had a "perfect" SWR at resonance.

7 3
 
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Crawdad said:
I have learned through practice with a Rig Expert, that super low SWR does not necessarily mean a super efficient antenna. I tune for resonance near the middle of the band and the SWR is not always minimal, but the reactance values are very low. Watching the amount of reflected power on voice peaks tells me most of the power is going to the antenna, hopefully being radiated. And this is with antennas in less than optimum locations/situations. IMO, SWR is not the most important factor and an antenna can be an efficient radiator with a SWR from 1.5:1 or higher up to 2:1, if the reactance values are as close to resonance as possible.

7 3
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Good stuff

73
Jeff
 
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Crawdad said:
I have learned through practice with a Rig Expert, that super low SWR does not necessarily mean a super efficient antenna. I tune for resonance near the middle of the band and the SWR is not always minimal, but the reactance values are very low. Watching the amount of reflected power on voice peaks tells me most of the power is going to the antenna, hopefully being radiated. And this is with antennas in less than optimum locations/situations. IMO, SWR is not the most important factor and an antenna can be an efficient radiator with a SWR from 1.5:1 or higher up to 2:1, if the reactance values are as close to resonance as possible.

And so far, I've not had a "perfect" SWR at resonance.

7 3
Click to expand...
Agree 100 %. Antenna science is not exact. Close counts. I've talked DX on antennas that folks said could not get out of their own way. I wish someone would invent a tester that you could point at an antenna and see the radiation pattern on a monitor. Sure would make things easier.

-399
 
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Crawdad said:
I have learned through practice with a Rig Expert, that super low SWR does not necessarily mean a super efficient antenna. I tune for resonance near the middle of the band and the SWR is not always minimal, but the reactance values are very low. Watching the amount of reflected power on voice peaks tells me most of the power is going to the antenna, hopefully being radiated. And this is with antennas in less than optimum locations/situations. IMO, SWR is not the most important factor and an antenna can be an efficient radiator with a SWR from 1.5:1 or higher up to 2:1, if the reactance values are as close to resonance as possible.

And so far, I've not had a "perfect" SWR at resonance.

7 3
Click to expand...
Okay . So how do I tune for resonance and reflect powerof modulation. Antenna analyzer and oscilloscope?
 
MadisonMod said:
Okay . So how do I tune for resonance and reflect powerof modulation. Antenna analyzer and oscilloscope?
Click to expand...
Antenna analyzer. No scope required. Reflected power is a function of your SWR meter.

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While this might not be easy with a semi truck you can check your transmit pattern without a meter. Get a friend that has a HF radio or an Export that has a large S meter on it. At night on a quiet channel have them sit 3-5 miles away or if they are on a base station even better. Then in a large parking lot throw a dead key and drive in a circle. At each mark point of 12,3,6, and 9:00 you can say what your position is while still keyed up. Your friend should be able to give you S readings at the various directions you were facing.
 
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9C1Driver said:
While this might not be easy with a semi truck you can check your transmit pattern without a meter. Get a friend that has a HF radio or an Export that has a large S meter on it. At night on a quiet channel have them sit 3-5 miles away or if they are on a base station even better. Then in a large parking lot throw a dead key and drive in a circle. At each mark point of 12,3,6, and 9:00 you can say what your position is while still keyed up. Your friend should be able to give you S readings at the various directions you were facing.
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Ah , good idea. Thanks.
I'm not sure where to post , but I have a k30 mag antenna. All the sudden the receive disappeared and swr went off the chart. I opened the magnet and it coax is burnt. It looks like they used a resistor or something between the transmit and shield. Does anyone have any idea? Have you ever seen before? What does that do ?
 

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9C1Driver said:
While this might not be easy with a semi truck you can check your transmit pattern without a meter. Get a friend that has a HF radio or an Export that has a large S meter on it. At night on a quiet channel have them sit 3-5 miles away or if they are on a base station even better. Then in a large parking lot throw a dead key and drive in a circle. At each mark point of 12,3,6, and 9:00 you can say what your position is while still keyed up. Your friend should be able to give you S readings at the various directions you were facing.
Click to expand...
Okay. So I used mfj antenna analyzer today and the antenna was reading 80 ohms . I changed the horizontal angle of antenna a few degrees and rechecked. I ended up moving it about 1/4 " and now the analyzer is reading 50 ohms. It also changed the 1.35 swr down to 1.2. Now channels 1 & 40 are same. now I will find someone with a base and see about direction of signal. I will try a larger antenna on the signal strength meter when I can find one or perhaps make one ? My second thoughts are to add a new mount from the frame of the truck about 1 foot behind the cab. Approximately 3 feet tall with a 6" x 8" plate on top that I could mount a puck too. This might help the reflection of the signal. Any thoughts? Or do you know anyone who makes custom antenna mounts ?
 
Hello everyone. Is it possible to Calculate the DB gain of you're signal from an antenna, or how much gain an antenna is producing?
 

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