Georgy.Moshkin
Full Member level 5
Setup:
Patch array antenna fed with a signal F(t)=F1(t)+F2(t)+F3(t), in other words there are simultaneously three frequencies.
F2(t) signal component may be fed to each patch with arbitrary phase shift.
Question:
Is it possible to cancel out F2 frequency by feeding each odd-numbered patch with F2 signal shifted by 180°?
Each odd-element will be fed with Fcancellation(t)=F1(t)+F2(t+dt180°)+F3(t).
Each even-numbered fed with F(t)=F1(t)+F2(t)+F3(t).
So at some distance from antenna F2 will be cancelled out.
I think that this may be possible, and best cancellation will be observed at boresight direction.
Then cancellation will degrade and it may be estimated using using beam steering / phase monopulse related formulas,
For example, with λ/2 spacing beam steering pointing to Theta=5 degree will require phase shift of 2*180*0.5*Sin(5)=15.6 [deg] between adjacent patches. Using this formulas backwards to estimate F2 signal cancellation effect.
at boresight (Theta=0) direction i expect to see cancellation >-20dB
Estimating cancellation by comparing waveform
F2nocancellation(x)=Sin(x) and
F2cancellation(x)=(Sin(x)+Sin(x+(180+15.6)*Pi/180)
which will lower F2 signal level by -6 to -12dB instead of -20dB
Is this even possible or something is not taken into account?
Patch array antenna fed with a signal F(t)=F1(t)+F2(t)+F3(t), in other words there are simultaneously three frequencies.
F2(t) signal component may be fed to each patch with arbitrary phase shift.
Question:
Is it possible to cancel out F2 frequency by feeding each odd-numbered patch with F2 signal shifted by 180°?
Each odd-element will be fed with Fcancellation(t)=F1(t)+F2(t+dt180°)+F3(t).
Each even-numbered fed with F(t)=F1(t)+F2(t)+F3(t).
So at some distance from antenna F2 will be cancelled out.
I think that this may be possible, and best cancellation will be observed at boresight direction.
Then cancellation will degrade and it may be estimated using using beam steering / phase monopulse related formulas,
For example, with λ/2 spacing beam steering pointing to Theta=5 degree will require phase shift of 2*180*0.5*Sin(5)=15.6 [deg] between adjacent patches. Using this formulas backwards to estimate F2 signal cancellation effect.
at boresight (Theta=0) direction i expect to see cancellation >-20dB
Estimating cancellation by comparing waveform
F2nocancellation(x)=Sin(x) and
F2cancellation(x)=(Sin(x)+Sin(x+(180+15.6)*Pi/180)
which will lower F2 signal level by -6 to -12dB instead of -20dB
Is this even possible or something is not taken into account?