Difference in field strength reading using different antennas
 

We are testing a field strength meter and decided to measure a low
power (100mW) FM transmission using an unused frequency. On the first
test, we used a dipole antenna connected to a balance-unbalance device
before being connected to the field strength meter. The second test we
utilized an FM telescoping antenna.

Using the dipole, when we turned off the transmitter, the reference
field strength reading remained pretty steady. But when we used the
monopole, the reference reading jumped up and down by a few microvolts
even with the FM transmitter off.

What would be an explanation to this?

Thank you!

Difference in field strength reading using different antennas
 

On May 8, 12:22 pm, FG wrote:
We are testing a field strength meter and decided to measure a low
power (100mW) FM transmission using an unused frequency. On the first
test, we used a dipole antenna connected to a balance-unbalance device
before being connected to the field strength meter. The second test we
utilized an FM telescoping antenna.

Using the dipole, when we turned off the transmitter, the reference
field strength reading remained pretty steady. But when we used the
monopole, the reference reading jumped up and down by a few microvolts
even with the FM transmitter off.

What would be an explanation to this?

Thank you!


Nearby, or very strong mostly vertically polarized signals would be my
first
guess... Remember that the fs meter is not tuned and responds to most
any frequencies within reason. Maybe a police car was in the
neighborhood
and he was keying his radio.. Could be anyone in the area..
MK

Difference in field strength reading using different antennas
 

"FG" wrote in message
ups.com...
We are testing a field strength meter and decided to measure a low
power (100mW) FM transmission using an unused frequency. On the first
test, we used a dipole antenna connected to a balance-unbalance device
before being connected to the field strength meter. The second test we
utilized an FM telescoping antenna.

Using the dipole, when we turned off the transmitter, the reference
field strength reading remained pretty steady. But when we used the
monopole, the reference reading jumped up and down by a few microvolts
even with the FM transmitter off.

What would be an explanation to this?

Thank you!


I dont think there is any such ting as an unused frequency in the FM band

There will probably always be a microvolt or two floating around and it
could very well be polarity sensitive.

Jimmie