On 28/02/2023 01:20, henry.powell...@gmail.com wrote:
Hello, again.
I tried with step attenuators and the result is there was difference
around 2dB between 0 degree and 180 degree rotation of horn without
attenuator. When I connected the attenuators to rx and tx paths, the
difference raised around 10dB. When I change step of attenuator, I can
decrease difference at 2, 3dB. But I can’t fix this.
Yes my signal is CW wiothout offset. I tried to shift the center
frequency of receiver. But the result is same. But I discovered
something, When I switch the center frequency with 10MHz step, like
starting 4GHz to 4.4GHz with 10MHz step, there is no difference at 0
and 180 degree of horn in some frequencies. And also, If change the
antenna location, I can find the location which is no difference at 0
and 180 degree in same frequency like just 4GHz.
VNA is using swept technique. I know the values are uncalibrated in
GNU Radio, I don’t care about the actual values at this stage, maybe i
can improve the systems in the coming days but not now. Actually, When
I rotate the Horn 45 degree in roll-axes, I can see 3dB decrease. In
cross position, I mean 90 degree, Values are sensible. I can see the
same result in VNA at the same degree except 180 degree. That doesn’t
make sense.
Thanks for all answers.
_______________________________________________
USRP-users mailing list -- usrp-users@lists.ettus.com
To unsubscribe send an email to usrp-users-le...@lists.ettus.com
Henry:
The fact that antenna position within your space makes a difference
indicates to me that this is utterly unrelated to the radio at all.
I use USRPs in radio astronomy, where we try to get repeatable
measurements day-over-day. We generally achieve that to within
about 0.4dB -- and only a tiny fraction of the non-repeatable is the
radio.
_______________________________________________
USRP-users mailing list -- usrp-users@lists.ettus.com
To unsubscribe send an email to usrp-users-le...@lists.ettus.com
