wrote:
Thanks guys... Some of these ideas might work. Sorry, I should have
given more details... It's basically receive antennas in the 1000 MHz
range, and I don't have access to the transmitters that will be used
with them. I'm just trying to find a way to see where they're tuned
and then be able to tune them if they're off. So if I went with an SWR
meter, maybe there's an easy way to generate a signal to use that? I
have an Autek that goes to 500 MHz. Somebody mentioned using a
frequency doubler, but I'm not sure how that would work.

If you know the antenna impedance at resonance is tolerable, then SWR is
adequate. If you'll need to design a matching network, though, you'll
need to know separate R and X components, so you'd need a network
analyzer or equivalent.

Have you ever calculated how much signal loss occurs as a result of
mismatch? You might find you're wasting your time bothering with it.

Roy Lewallen, W7EL

On Mar 11, 12:56*pm, Roy Lewallen wrote:
wrote:
Thanks guys... Some of these ideas might work. Sorry, I should have
given more details... It's basically receive antennas in the 1000 MHz
range, and I don't have access to the transmitters that will be used
with them. I'm just trying to find a way to see where they're tuned
and then be able to tune them if they're off. So if I went with an SWR
meter, maybe there's an easy way to generate a signal to use that? I
have an Autek that goes to 500 MHz. Somebody mentioned using a
frequency doubler, but I'm not sure how that would work.

If you know the antenna impedance at resonance is tolerable, then SWR is
adequate. If you'll need to design a matching network, though, you'll
need to know separate R and X components, so you'd need a network
analyzer or equivalent.

Have you ever calculated how much signal loss occurs as a result of
mismatch? You might find you're wasting your time bothering with it.


Believe me, I tend to agree... As is, they tend to be about a 4.0:1
and maybe 55 MHz off the mark on average. But like I said, this is a
receive application in 1000 MHz. So real world, you wouldn't even hear
a difference in that. But it's a numbers game and they won't be happy
until they see the right numbers. But that's why it's hard for me to
justify spending big bucks for the ability to test this.

And Jerry, good idea... I actually did run the design as a model, but
it showed that it should be correct as is. So something else is
setting them off a bit. Probably the radomes or something.

wrote in message
...
On Mar 11, 12:56 pm, Roy Lewallen wrote:
wrote:
Thanks guys... Some of these ideas might work. Sorry, I should have
given more details... It's basically receive antennas in the 1000 MHz
range, and I don't have access to the transmitters that will be used
with them. I'm just trying to find a way to see where they're tuned
and then be able to tune them if they're off. So if I went with an SWR
meter, maybe there's an easy way to generate a signal to use that? I
have an Autek that goes to 500 MHz. Somebody mentioned using a
frequency doubler, but I'm not sure how that would work.

If you know the antenna impedance at resonance is tolerable, then SWR is
adequate. If you'll need to design a matching network, though, you'll
need to know separate R and X components, so you'd need a network
analyzer or equivalent.

Have you ever calculated how much signal loss occurs as a result of
mismatch? You might find you're wasting your time bothering with it.


Believe me, I tend to agree... As is, they tend to be about a 4.0:1
and maybe 55 MHz off the mark on average. But like I said, this is a
receive application in 1000 MHz. So real world, you wouldn't even hear
a difference in that. But it's a numbers game and they won't be happy
until they see the right numbers. But that's why it's hard for me to
justify spending big bucks for the ability to test this.

And Jerry, good idea... I actually did run the design as a model, but
it showed that it should be correct as is. So something else is
setting them off a bit. Probably the radomes or something.

Hi

You need only a decent L-band generator, a directional coupler, and a
detector to get the VSWR. Where is SoCal?

Jerry KD6JDJ