Testing at higher frequencies
 

Does anyone know if there's a way I could test using an analyzer that
does about 50-500 MHz, but at a 1000-ish frequency? I need to test
something in that area, but I don't have equipment that will go that
high. Seems like any analyzer that goes that high is thousands of
dollars. Does anyone know if there's somebody that rents Anritsus in
SoCal maybe? Any suggestions are welcome. I mainly just need to do
SWR.

Thanks,

Testing at higher frequencies
 

Testing at higher frequencies
 

wrote in message
...
Does anyone know if there's a way I could test using an analyzer that
does about 50-500 MHz, but at a 1000-ish frequency? I need to test
something in that area, but I don't have equipment that will go that
high. Seems like any analyzer that goes that high is thousands of
dollars. Does anyone know if there's somebody that rents Anritsus in
SoCal maybe? Any suggestions are welcome. I mainly just need to do
SWR.

Thanks,

Do you have an amateur radio license? There are clubs in the Southern
California area.

Jerry KD6JDJ

Testing at higher frequencies
 

I did find Electrorents. $700 for a month... I didn't think it would
be that much. It's mainly just for basic stuff, like SWR. I'm not a
ham. Seems like anything that goes past 500 MHz is really expensive.

Testing at higher frequencies
 

Testing at higher frequencies
 

wrote:
I did find Electrorents. $700 for a month... I didn't think it would
be that much. It's mainly just for basic stuff, like SWR. I'm not a
ham. Seems like anything that goes past 500 MHz is really expensive.


http://birdtechnologies.thomasnet.co...ers?&forward=1

Testing at higher frequencies
 

A couple of options here. Not knowing your actual need for accuracy etc
makes it hard to guess!

From my standpoint I'd probably just adjust an antenna for max field
strength but if I wanted actual VSWR meaurement or minimizing same I'd
probably use a directioinal coupler and a sensitive voltmeter.

A DC is essentially the active component of a power/VSWR measuring
device. AT 1GHz I have seen PCB designs with SMA connectors that you
just put in circuit, measure the volts, reverse its direction, measure
the volts again and calculate the VSWR. Pretty simple and cheap stuff.
The biggest problem is preserving the impedance across the DC device
itself. You can use teflon PC board for example to help out on this. You
will also need to think about the calibration of the thing because the
diode is not a linear device and needs some volts to get over the
forward drop. You can also DC bias it but those components will affect
accuracy over temperature change etc.

Still a good general purpose tool though. You can even make loads that
would look like known impedances to calibrate the thing.

Have a look around for these. You'll be impressed by the low price. They
are after all just a lump of PCB, two connectors, a microwave diode and
a filter cap! You'll have to supply your own voltmeter!

Cheers Bob VK2YQA

wrote:
I did find Electrorents. $700 for a month... I didn't think it would
be that much. It's mainly just for basic stuff, like SWR. I'm not a
ham. Seems like anything that goes past 500 MHz is really expensive.

Testing at higher frequencies
 

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.

Testing at higher frequencies
 

Testing at higher frequencies
 

wrote in message
...
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.

Hi

It has been my experience that the input impedance to the antenna can be
fairly well predictated by EZNEC is you are able to describe the antenna to
the program.

Jerry KD6JDJ

Testing at higher frequencies
 

Testing at higher frequencies
 

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.

Testing at higher frequencies
 

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