Hi Henry, I am unsure if you tried with an "LO offset" or if you just changed your center frequency. Changing the center frequency will not avoid the problems which can occur at the LO frequency.
There are two ways you can create a CW signal that is offset from the LO frequency. You can either change the "LO offset" setting of the tuning options or you can use a waveform that inherently has an offset frequency. Rob On Tue, Feb 28, 2023 at 1:21 AM <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 >
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