New Product: RTL-SDR Blog 1090 MHz ADS-B LNA

We're happy to announce the release of our new high performance low noise amplifier (LNA) for improving 1090 MHz ADS-B reception. The LNA uses a low noise figure high linearity two stage MGA-13116 amplifier chip and three stages of filtering to ensure that strong signals or interference will not overload either the amplifier or SDR dongle.

The LNA is currently only available from our Chinese warehouse, and costs US$24.95 including shipping. Please note that the price may increase slightly in the future, and that Amazon USA may not be stocked until March.

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RTLBlog_LNA_Product_Flat
RTLBlog_LNA_Product_PCB_Flat

An LNA can help improve ADS-B reception by reducing the noise figure of the system and by helping to overcome losses in the coax cable and/or any other components such as switches and connector in the signal path. To get the best performance from an LNA, the LNA needs to be positioned close to the antenna, before the coax to the radio.

The gain of the RTL-SDR Blog ADS-B LNA is 27 dB's at 1090 MHz, and out of band signals are reduced by at least 60 - 80 dB's. Attenuation in the broadcast FM band and below 800 MHz is actually closer to over 100 dB's. In the LNA signal path there is first a low insertion loss high pass filter that reduces the strength of any broadcast FM, TV, pager or other similar signals that are usually extremely strong. Then in between the first and second stage of the LNA is a SAW filter tuned for 1090 MHz. A second SAW filter sits on the output of the LNA. The result is that strong out of band signals are significantly blocked, yet the LNA remains effective at 1090 MHz with a low ~1 dB noise figure.

The LNA is also protected against ESD damage with a gas discharge tube and low capacitance ESD diode. But please always remember that your antenna must also be properly grounded to prevent ESD damage.

Finally please note that this LNA requires bias tee power to work. Bias tee power is when the DC power comes through the coax cable. The RTL-SDR V3 has bias tee power built into it and this can be activated in software. See the V3 users guide for information on how to activate it. Alternatively if you don't own a dongle with bias tee built in, then an external bias tee can be used and those can be found fairly cheaply on eBay. Finally, if you are confident with soldering SMT components, then there are also pads and a 0 Ohm resistor slot on the PCB to install an LDO and power the LNA directly.

Specification Summary:

  • Frequency: 1090 MHz
  • Gain: 27 dB @ 1090 MHz
  • Return Loss: -16 dB @ 1090 MHz (SWR = 1.377)
  • Noise Figure: ~1 dB
  • Out of band attenuation: More than 60 dB
  • ESD Protection: Dual with GDT and ESD Diode
  • Power: 3.3 - 5V via bias tee only, 150 mA current draw
  • Enclosure: Aluminum enclosure
  • Connectors: Two SMA Female (Male to Male adapter included)

Testing

We tested our new LNA against another ADS-B LNA with filter built in that is sold by another company and the FlightAware Prostick+ dongle in an environment with strong out of band signals such as pagers, broadcast FM, DVB-T and GSM signals. The results showed that the RTL-SDR Blog ADS-B LNA gathered the most ADS-B packets. In the tests both LNA's were connected on the receiver side to be fair to the FA dongle. Improved performance could be achieved by moving the LNA to the antenna side.

Other ADS-B LNA vs RTL-SDR Blog ADS-B LNA Received Messages
FlightAware Prostick+ vs RTL-SDR Blog ADS-B LNA Received Messages

Checking in SDR# for out of band signals also showed that the RTL-SDR Blog ADS-B LNA significantly reduces those strong out of band signals, whereas the others have trouble blocking them out. Below we show the results as well as some measurements.

RTL Blog ADS-B LNA @ 1090 MHz

RTL Blog ADS-B LNA @ 1090 MHz

Other ADS-B LNA @ 1090 MHz

Other ADS-B LNA @ 1090 MHz

FlightAware Prostick+ @ 1090 MHz

FlightAware Prostick+ @ 1090 MHz

RTL Blog ADS-B LNA tuned to Broadcast FM

RTL Blog ADS-B LNA tuned to Broadcast FM

Other ADS-B LNA tuned to Broadcast FM

Other ADS-B LNA tuned to Broadcast FM

FlightAware Protstick+ tuned to Broadcast FM

FlightAware Protstick+ tuned to Broadcast FM

RTL Blog ADS-B LNA tuned to a DVB-T Signal

RTL Blog ADS-B LNA tuned to a DVB-T Signal

Other ADS-B LNA tuned to a DVB-T Signal

Other ADS-B LNA tuned to a DVB-T Signal

FlightAware Prostick+ tuned to a DVB-T Signal

FlightAware Prostick+ tuned to a DVB-T Signal

RTL Blog ADS-B LNA tuned to a GSM Signal

RTL Blog ADS-B LNA tuned to a GSM Signal

Other ADS-B LNA tuned to a GSM Signal

Other ADS-B LNA tuned to a GSM Signal

FlightAware Prostick+ tuned to a GSM Signal

FlightAware Prostick+ tuned to a GSM Signal

Gain Measurements

Gain Measurements

Return Loss

Return Loss

Simulated Gain/Attenuation

Simulated Gain/Attenuation

Conclusion

This RTL-SDR Blog ADS-B LNA can significantly improve ADS-B reception, especially if you are in an environment with strong out of band signals. Even if you are not, the low noise figure design will improve reception regardless.

13 comments

  1. Vince

    Just received mine in the mail today, removed a satellite inline amp (was getting power from DirecTV injector) and the Flight Aware filter and put this amp in its place. So far so good but today is Saturday, a bad day to compare. I noticed the Airspy Mini was drawing 270 mA and with the built-in bias tee and the rtl-sdr amp it is now drawing 430 mA.

  2. Anonymous

    Will this also work for UAT on 978 MHz? The flightaware+ filter has a sharp cut off that prevents usage on 978.

  3. Jonis

    It’s really wise to create a new product with a near-discontinued chip? (MGA-13116). Broadcom catalog say it will be discontinued soon, to not use in new designs.

    • admin

      Yeah unfortunately they just released the obsolescence note in December 2017, and we’d already finished the prototyping and had bought the chips just before then. But the chip stock we have now should be enough for at least 1-2 years as I don’t expect the demand to be super high.

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