Measure the gain of LNA4All

antennas

#1

In order to amplify the weak signal and reduce (as possible) the noise that captured by antenna we use the Low Noise Amplifier(LNA), LNA4all.

The LNA4all is connected in the output of antenna and in the input of receiver (as close as possible).
The properties of LNA4all are:

  • Noise Figure: <1dB
  • Gain: 11.5 - 23.5 dB
  • Frequency range : 28kHz - 2.5GHz
  • Power Supply: 6 - 12V or 5V (regulated)

The antenna input and output to receiver are matched to 50 ohms Low cost

We measure the LNA4all to confirm the above values. We used miniVNA Tiny and the 20dB attenuator.

The output signal (DUT) of minyVNA Tiny is 5.15dB after the LNA4all the signal may be ~25dB, but the maximum measured signal by minyVNA Tiny is 10dBm (10mW).
So we have problem to measure without use attenuator. With above case we decided to use 20dB attenuator.

20dB attenuator

In below figures are presented the testing setup of LNA4all with attenuator and miniVNA and the measurements which is exported from the miniVNA.

Testing setup

Measurements

The gain of the LNA4all in ~147MHz is 20dB+3.07dB-5.15dB = 17.92 dB

  • in ~283MHz is 20dB+3.33dB-5.15dB = 18.18 dB
  • in ~437MHz is 20dB+2.32dB-5.15dB = 17.17 dB

#2

Hi,
Can you please clarify why we want to use a LNA in the first place? Did you have problems with reception S/N ratio on rtlsdr?


#3

Hey, sorry for the late response, with @pierros we measured that the noise is reduced with LNA4ALL instead of the internal LNA of rtl-sdr dongles.


#4

plz can u tell me away about how to use mini vna tiny as asignal generator ?


#5

Who is currently using a LNA productively and would you consider adding it to the electronics baseline? How is the success without LNA compared?


#6

I didnt well understand why 5.15dB. Can you explain me why ?


#7

We had measured that this is the power out on miniVNA.


#8

Why the unit is dB ?


#9

yes, it isn’t correct, the correct unit is dBm. But the gain calculation isn’t changed.


#10

Ok, thank you I understand :slight_smile:
I was thinking about adding the measurements of others LNA, should I put it here or in the wiki ?


#11

:slight_smile: i also start to measure filters and LNAs.

I think it is better to add it in a wiki page.


#12

I see you’ve got my favorite LNA in the bottom there… I look forward to the wiki page :slight_smile: