Andy,

Here are a couple of comments:

It would be helpful to know the characteristics of your antenna. Is there any technical documentation available which would give some numbers such as opening angle / gain?

Looking at the picture of the antenna is seems that the various elements are internally connected to provide a single port, so the antenna has a? fixed pattern. There may be one disadvantage: Since the coupling elements will inevitably have some loss, this adds noise. For terrestrial applications for which the antenna was intended, this will not matter too much as the antenna will pick up thermal noise from the ground anyway. For astronomical applications, however, this may be a disadvantage. Without knowing more details it is not possible to assess how much on an issue this might be.

The next thing I noticed is that you have a cable of maybe 1m length between the antenna port and the LNA. It would be better to have the LNA directly at the antenna port. The attenuation of the cable will introduce noise which can be avoided.

I assume your spectra were taken with the antenna pointing straight upwards. It would be helpful to know the coordinates of your location and the time when the recording was taken in order to determine the sky location where you were pointing.

If I interpret correctly your recording taken with ezRA, you have been recording at 1420 MHz with 2.6 MHz bandwidth and then displayed the total power in that band over time. In that case you would have received emission from hydrogen plus a small contribution from the synchrotron radiation in the galactic plane. With small antennas you can only expect to see the hydrogen emission. In this case, it would be better to narrow the bandwidth to the range of the hydrogen spectrum to increase you SNR. 500 kHz around 11420.4 MHz would be a good starting point. I don’t think you have actually as signal from the galactic plane in your plot.

As far as your signal at 1419.6 MHz is concerned, this would correspond to a redshift of ~ 170 km/s if it were hydrogen (you seem to have done something wrong in your calculation). ?Such velocities do not occur in our galaxy, so this must be something else (or there was something weird with the frequency setting of your SDR).

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Best regards,

Wolfgang

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