Tagged: low noise amplifier

New Products in Our Store: Wideband LNA + Spare V3 Metal Enclosures

We've just released two new products in our store. The first is a low cost general purpose wideband LNA and the second is some spare RTL-SDR V3 aluminum enclosures. The wideband LNA is currently available for shipping from our Chinese warehouse and will be available on Amazon in a few days time. It costs US$17.95 including worldwide free shipping. The spare aluminum enclosure is only available from our Chinese warehouse and costs US$5.95.

Please Click Here to Visit our Store

Wideband LNA

The Wideband LNA is based on the Qorvo SPF4189Z LNA chip (datasheet pdf) which has the following declared specs:

  • Frequency range of 50 MHz to 4000 MHz
  • Noise figure = 0.6dB @ 900 MHz
  • OIP3 = 39.5 dBm @ 900 MHz
  • P1 Saturation = 22.7 dBm @ 1960 MHz
  • Gain = 18.7 dB @ 900 MHz

Compared to most of the other SPF5189Z LNAs found on eBay, our wideband LNA comes standard with a full conductive metal case, includes ESD protection on the antenna input, and is by default powered via 3 - 5V bias tee power. Our RTL-SDR Blog V3 dongles have a 4.5V bias tee built in, so they can be used to power this LNA. Direct power can be enabled simply by changing a jumper position, and removing the metal case.

This is a general purpose wideband LNA. It is useful for reducing the noise figure and thus increasing SNR, and for overcoming coax loss on all supported frequencies between 50 - 4000 MHz. However, because it is wideband you may need additional filtering if you have strong overloading signals in your area. If you're mostly interested in improving ADS-B reception, then we instead recommend our Triple Filtered ADS-B LNA which is also available at our store. The specs of the SPF5189Z are similar to that of PGA-103+ or PSA4-5043+ based LNAs. In the image slider below we compare the gain with the LNA4ALL which is a PSA4-5043+ based LNA.

Spare Aluminum Enclosure

The second product is some spare RTL-SDR Blog V3 aluminum enclosure. A few readers of this blog contacted us as they found RTL-SDR V3 enclosures to be a good fit (after being cut down to size) for home made filters, other LNAs and for FlightAware dongles. Our spare enclosures come with two SMA side panels, and one USB side panel. There is only limited stock of this product at the moment. Note that we're not including a thermal pad, since FlightAware dongles do not require additional cooling since they operate at 1.09 GHz. Additional cooling via thermal pad is only needed for stable operation when using RTL-SDRs above ~1.5 GHz.

WidebandLNA_Store
WidebandLNA_PCB_Store
wideband_lna_gain
spare_enclosure_shop

New Products in Our Store: Wideband LNA + Spare V3 Metal Enclosures

We've just released two new products in our store. The first is a low cost general purpose wideband LNA and the second is some spare RTL-SDR V3 aluminum enclosures. The wideband LNA is currently available for shipping from our Chinese warehouse and will be available on Amazon in a few days time. It costs US$17.95 including worldwide free shipping. The spare aluminum enclosure is only available from our Chinese warehouse and costs US$5.95.

Please Click Here to Visit our Store

Wideband LNA

The Wideband LNA is based on the Qorvo SPF4189Z LNA chip (datasheet pdf) which has the following declared specs:

  • Frequency range of 50 MHz to 4000 MHz
  • Noise figure = 0.6dB @ 900 MHz
  • OIP3 = 39.5 dBm @ 900 MHz
  • P1 Saturation = 22.7 dBm @ 1960 MHz
  • Gain = 18.7 dB @ 900 MHz

Compared to most of the other SPF5189Z LNAs found on eBay, our wideband LNA comes standard with a full conductive metal case, includes ESD protection on the antenna input, and is by default powered via 3 - 5V bias tee power. Our RTL-SDR Blog V3 dongles have a 4.5V bias tee built in, so they can be used to power this LNA. Direct power can be enabled simply by changing a jumper position, and removing the metal case.

This is a general purpose wideband LNA. It is useful for reducing the noise figure and thus increasing SNR, and for overcoming coax loss on all supported frequencies between 50 - 4000 MHz. However, because it is wideband you may need additional filtering if you have strong overloading signals in your area. If you're mostly interested in improving ADS-B reception, then we instead recommend our Triple Filtered ADS-B LNA which is also available at our store. The specs of the SPF5189Z are similar to that of PGA-103+ or PSA4-5043+ based LNAs. In the image slider below we compare the gain with the LNA4ALL which is a PSA4-5043+ based LNA.

Spare Aluminum Enclosure

The second product is some spare RTL-SDR Blog V3 aluminum enclosure. A few readers of this blog contacted us as they found RTL-SDR V3 enclosures to be a good fit (after being cut down to size) for home made filters, other LNAs and for FlightAware dongles. Our spare enclosures come with two SMA side panels, and one USB side panel. There is only limited stock of this product at the moment. Note that we're not including a thermal pad, since FlightAware dongles do not require additional cooling since they operate at 1.09 GHz. Additional cooling via thermal pad is only needed for stable operation when using RTL-SDRs above ~1.5 GHz.

WidebandLNA_Store
WidebandLNA_PCB_Store
wideband_lna_gain
spare_enclosure_shop

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.

Click here to visit our store

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.

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.

In addition please remember that this is a high gain LNA. It is expected to be used at the antenna side, with some 3+ db loss expected on the coax. However, if desired, it can still be used on the receiver side. If used on the receiver side or with a low loss run of coax, you will need to tune the RF gain on the RTL-SDR dongle. By default most software sets the RF gain to maximum. We recommend turning the RTL-SDR RF gain down to about 32 dB if connecting it directly to the dongle, otherwise the high input power may overload the dongle causing poor performance.

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)

Dimensions:

46.5 x 32 x 15.6 mm (not including the SMA).
Including the SMA the length is 69.8 mm.

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

VNA_180530_231521

Reviews

Tyson Power YouTube Review

Radio For Everyone Review

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.

How an LNA can Improve VHF Reception with an RTL-SDR

Over on his YouTube channel Adam 9A4QV has uploaded a video showing how an LNA work to improve signal SNR on VHF, as long as the LNA is placed close to the antenna. Adam is the manufacturer and seller of the popular LNA4ALL low noise amplifiers.

On UHF and high frequencies an LNA can help by reducing the system noise figure, but on VHF this effect is small. But if the LNA is placed near the antenna then the LNA can still help significantly by overcoming any losses in the coax cable, filters, switches or any other lossy components in the signal path. It might also help create a better SWR match for the dongle and antenna. The video has some sound issues in during the demonstration part, but on his Reddit thread Adam writes:

Well, monitoring the beacon signal on 144.478 Mhz the S/n without LNA was just 10dB and cannot improve with decreasing the gain. Inserting the LNA in line, close to the antenna, through the Bias-T the S/n improve from 10dB to 23dB.

To meet the most of the user's conditions I was using the RTL-SDR dongle and the 20 meters of RG-6 coaxial cable with F-connectors.

It is obvious that using the LNA on the antenna can improve your reception even on the VHF band. Using the proper bandpass filter instead of a single FM stop filter will give much better results.

LNA4ALL on the VHF close to antenna effect

Comparing Two LNA’s for HRIT/LRIT (GOES) Reception

Over on his blog Lucas Teske has been comparing the LNA4ALL and an SPF5189 LNA from eBay on HRIT/LRIT reception from GOES satellites. SPF5189 LNA’s can be found on eBay for less than $8 USD, with free shipping from China, whereas the LNA4ALL costs 27 Euros shipped from Croatia. GOES is a geosynchronous orbit weather satellite which requires a satellite dish or other high gain antenna to receive. It downlinks at about 1.7 GHz, which means that a high quality LNA with low noise figure and good PCB design is needed for reception.

In his post Lucas mentions how he saw a review on eBay stating that the SPF5189 did not work at L-band. However, he found that odd as all of his SPF5189 LNA’s seemed to work just fine with L-band reception. So he did a benchmark comparing the SPF5189 to the PSA5043+ based LNA4ALL which is known to work well on L-band.

From his comparisons he found that the SPF5189 does indeed work well on L-band, and is comparable to the LNA4ALL. He concludes that the reviewer must have received a bad unit, or didn’t know what he was doing.

Lucas also makes an important note regarding the PCB design of these LNA’s. Even though the SPF5189 and PSA5043 chips have similar specs, with LNA’s the design of the PCB is crucial, as a poor design can significantly degrade performance. With the LNA4ALL you can be sure that the design is good, although the SPF5189 LNA’s currently on eBay look to be designed okay as well. Though with some eBay sellers there is no guarantee that you will receive a good board. We note that we have seen some really poor designs for PSA5043 LNA’s out there as well.

The eBay SPF5189 LNA vs the LNA4ALL from 9A4QV
The eBay SPF5189 LNA vs the LNA4ALL from 9A4QV

FlightAware Release their Pro Stick Plus: An ADS-B Optimized RTL-SDR with LNA and 1090 MHz Filter Built in

Back in March of this year we posted about the release of the FlightAware “Pro Stick”. The Pro Stick is FlightAware’s ADS-B optimized RTL-SDR dongle. It uses a low noise figure LNA on the RF front end to reduce the system noise figure, thus improving the SNR at 1090 MHz. Because the added gain of the LNA can easily cause overload problems if there are other strong signals around, FlightAware recommend using one of their 1090 MHz ADS-B filters in front of the dongle to prevent overload.

FlightAware have just come out with the “Pro Stick Plus” which is the same as their Pro Stick, but now with the 1090 MHz filter built into the dongle itself. The Pro Stick Plus costs $20.95 USD on Amazon, which is a good deal cheaper than buying the standard Pro Stick ($16.95 USD) plus their ADS-B filter ($19.95 USD), which totals $36.90. Customers outside of the USA can purchase the Pro Stick Plus from seller WiFi Expert on eBay for $29.95 USD.

FlightAware.com is a company that specializes in live air travel tracking. Most of their data comes from volunteers running RTL-SDR ADS-B receivers.

The new Pro Stick Plus RTL-SDR based ADS-B Receiver from FlightAware.
The new Pro Stick Plus RTL-SDR based ADS-B Receiver from FlightAware.

Over on their forums and on Amazon, they announced the device and specs. They wrote:

FlightAware is excited to announce the next evolution of USB SDR sticks for ADS-B reception! The new Pro Stick Plus USB SDR builds on the popular Pro Stick by adding a built-in 1090 MHz bandpass filter. The built-in filter allows for increased performance and range of reception by 10-20% for installations where filtering is beneficial. Areas with moderate RF noise, as is typically experienced in most urban areas, generally benefit from filtering. By integrating the filter into the SDR stick, we are able to reduce the total cost by more than 40% when compared to buying a Pro Stick and an external filter.

Specifications:

  • Filter: 1,075 MHz to 1,105 MHz pass band with insertion loss of 2.3 dB; 30 dB attenuation on other frequencies
  • Amp: 19 dB Integrated Amplifier which can increase your ADS-B range 20-100% more compared to dongles from other vendors which can increase range 10-20% over a Pro Stick in environments where filtering is beneficial
  • Native SMA connector
  • Supported by PiAware
  • R820T2 RTL2832U chips
  • USB powered, 5V @ 300mA

Note that this dongle is only for ADS-B at 1090 MHz, and not for 978 MHz UAT signals, as the filter will cut that frequency out.

Back in April, we did a review of the original Pro Stick. We found its performance on ADS-B reception to be excellent, but only when a filter was used. The low NF LNA theoretically improves the SNR of ADS-B signals by about 7-8 dB, but in reality there is too much gain causing signal overload everywhere, thus making reception impossible without the filter. Rural environments may not need a filter, but in a typical urban or city environment strong FM/TV/GSM/etc signals are abundant and these signals easily overloaded the Pro Stick when no filtering was used. This new Pro Stick Plus dongle completely solves that problem at a low cost with its built in filter.

Remember that if you are using a run of coax cable between the LNA and RTL-SDR, then it is more optimal to use an external LNA, like the LNA4ALL. Only an external LNA mounted near the antenna can help overcome coax, connector, filter and other losses as well as reducing the system noise figure. The FlightAware dongles are the optimal solution when they are mounted as close to the antenna as possible. This is usually the case when running the FlightAware feeder software on a Raspberry Pi.

We hope to soon review the Pro Stick Plus, however we assume it will operate nearly identically to the Pro Stick + FlightAware ADS-B filter combination.

Review: FlightAware ADS-B RTL-SDR + LNA Positioning

Recently FlightAware released a new RTL-SDR dongle sold at zero profit at $16.95 USD. It’s main feature is that it comes with an ADS-B optimized low noise amplifier (LNA) built directly into the dongle. FlightAware.com is a flight tracking service that aims to track aircraft via many volunteer ADS-B contributors around the world who use low cost receivers such as the RTL-SDR. In this post we will review their new dongle and hopefully at the same time provide some basic insights to LNA positioning theory to show in what situations this dongle will work well.

FlightAware Dongle Outside
FlightAware Dongle Outside

A good LNA has a low noise figure and a high IIP3 value. Here is what these things mean.

Continue reading

Tutorial on Properly Positioning a Preamp (LNA) in a Radio System

Radio blogger Anthony Stirk has made a post on his blog explaining some critical concepts behind understanding why it is important to position a low noise amplifier (LNA) near the radio antenna, rather than near the radio. In the post Anthony explains how the Noise Figure (NF) and linearity (IP3) of a radio system affect reception.

Using the free AppCAD RF design assistant software, Anthony explains how the noise figure of a system increases with longer coax cable runs, and how it can be reduced by placing an LNA right next to the antenna. He also explains why the sensitivity of the radio won’t increase if the LNA is placed close to the radio instead.

In addition to this, he also explains why adding more LNA’s to a system decreases the linearity (IP3) of the system and that if the receiver has a built in LNA that the system linearity can be severely degraded by adding extra LNA’s, causing easy overloading and intermodulation. In conclusion Anthony writes the following:

In summary, a setup with a good antenna system connected to a receiver with a built in LNA:

  • May not benefit from having a preamp at the antenna.
  • The presence of a built in LNA is detrimental to the linearity and may degrade the signals.

So in conclusion:

  • Put the preamp as close to the antenna as possible.
  • Receivers with a built in LNA may not get the most out of an antenna system or preamp.
  • Proper gain distribution guarantees better performance than one-size-fits-all solutions, both in terms of sensitivity and strong signals handling.

Optimal Setup: Antenna -> LNA -> Coax -> Receiver
Optimal Setup: Antenna -> LNA -> Coax -> Receiver
NF and Linearity Calculations
NF and Linearity Calculations in AppCAD

Testing an LNA on receiving a weak signal with the RTL-SDR

Over on YouTube Adam Alicajic the designer of the LNA4ALL low noise amplifier has uploaded a video showing the effect of an LNA on reception of a weak signal. He shows an example of how a very weak signal cannot be received by the RTL-SDR even when the gain is set to maximum unless an LNA is connected.

Adam has posted this video in regards to some statements saying that an LNA will only increase the noise floor and cannot bring signals out of the noise floor. There is a discussion about this on this Reddit thread.

DVB-T dongle + LNA = Myth or Truth