In the previous post I looked at my receiving equipment used for GOES16 to see if I could re-purpose it for reception of the so called hydrogen line at 1420MHz/21cm. The L band dish had a reasonable VSWR at 1420MHz, but the LNA/BPF was not suitable as it was centred on 1694MHz. I ordered a special LNA/BPF designed specifically for 21cm reception.
Figure 1 shows the frequency response of the 1420MHz LNA/BPF. The frequency source was just random noise in a 50ohm input termination. A more accurate result can be obtained by sweeping the unit with the NanoVNA which I will do in a later post. The bandwidth is approx. 75MHz and the gain approx. 20dB.
#1. – “RTL-SDR for Radio Astronomy – Planning