Dual antenna issues

I think you miss understand that statement. It refers to a 1/4 wave antenna.

leon
kc0iv

 

So at what point does resonance matter? Really?
I'm looking at this like trying to squeeze every last watt out of a radio. A few more watts isnt going to make a dicernible difference on the recieving end.
Doubling output power, the recieving station sees around a 3db increase, 4x the power equals 6db (1 S unit) and so on. I know that you already know this.
The same is true for antenna systems in regards to db gain and loss as the recieving station sees it. Specifically regarding antenna tuning, and disregarding other losses in the system at the moment, if an antenna is tuned to resonance, with an swr of 1.5:1, we can expect the reflected power loss to be approx 4%. For 100 watt radio that is 4watts, or a .177 db loss, 2.0:1 swr is around 11% or 11 watts a loss of .512db. Neither of which would be noticed what so ever on the other end.

If we are able to acheive a 1.1:1 swr, the antenna is still resonant, at some frequency, reflected power is 0, with 0db loss. Full output power, that has managed to make it through our lossy feedline, is being transmitted from our antenna. But we are not on our resonant frequency.
So, with our 1.1:1 swr, we are transmitting 440khz (bandwidth of the cb frequencies) away from our resonant frequency, with a narrow banded antenna, like the avg cb antennas are.
What would be the amount of signal loss expected on the recieving end? Or...
How far from our resonant frequency would we have to go, for there to be a dicernible difference at the recieving station?

 

these crapcadia trucks just fool a mfj or rig expert that their at 50 ohms and you get wonderful low swr readings there's a very serious grounding issue on these trks.... not like the old days solid built trks.. in 1994 the freightliner I was driving was a heavy but solid big ole biscuit... running dual antennas on it got me 30/35 audio out receive in..... hell the truck I'm driving now didn't come with antennas at all just that built in tied in to the stereo cb antenna nonsense those idiot Einstein's came up with... it's pathetic actually......

 

No misunderstanding at all. That's pretty much what I use in a mobile.

 

It's my understanding the newer trucks are using non metal roofs and thereby present a poor ground plane. I would be looking at a loaded 1/2 wave antenna.

Or look at going to another band/mode of transmission.

leon
kc0iv

 

Disagree, it has nothing to do with fooling the AA, there is a lot more that the AA does not see that goes on.

And to add to this I've said this a lot before and now going to return to it, too many of you put too much emphasis on SWR while it isn't all that important when you look at the entire system. You guys are close but still miss things with some of the thinking you have.

 

Very well said although I suspect it went over his head

 

mr.know it all. get a life if this forum is all you've got... but then I see it is. bwah ha ha ha