ghb
Advanced Member level 4
out of band rejection vs out of band gain
I need some clarification on this quoted specification
"For the purposes of rejecting undesired signals, the active portion of the GPS antenna shall have the following out-of-band rejection filter characteristic requirements as measured at the antenna assembly...
>25 dB at +/- 50 MHz of 1575.42 MHz"
My question is this, let's assume the LNA has a gain of 25 dB and I was measuring the performance of the LNA. Assuming calibrated VNA would I expect signals outside of +/- 50 MHz to be 0dB (25 dB down from the gain) or -25 dB (50 dB down from the gain) in order to meet spec?
I interpreted my requirements such that a -25 dB filter would be sufficient, is this the correct way to think?
thanks in advance
I need some clarification on this quoted specification
"For the purposes of rejecting undesired signals, the active portion of the GPS antenna shall have the following out-of-band rejection filter characteristic requirements as measured at the antenna assembly...
>25 dB at +/- 50 MHz of 1575.42 MHz"
My question is this, let's assume the LNA has a gain of 25 dB and I was measuring the performance of the LNA. Assuming calibrated VNA would I expect signals outside of +/- 50 MHz to be 0dB (25 dB down from the gain) or -25 dB (50 dB down from the gain) in order to meet spec?
I interpreted my requirements such that a -25 dB filter would be sufficient, is this the correct way to think?
thanks in advance