Category: News

EZNEC Pro Antenna Modelling Software will be free from 2022

EZNEC is a popular antenna modelling program created by W7EL which is based on the "Numerical Electromagnetics Code" or NEC. With a NEC based antenna modelling program it is possible to design antennas by modelling their geometry and connections, and then simulating parameters like radiation pattern gain and VSWR. You can also determine the effects of height, roof angles, nearby objects and more.

Originally the pricing was $99 for EZNEC, $149 for EZNEC+, $525 for EZNEC Pro/2 and $675 for EZNEC Pro/4. W7EL is retiring and from Jan 1 2022 EZNEC Pro/2 and EZNEC+ will be made free, and EZNEC Pro/4 will be discontinued. The source code will not be released, and no support will be provided.

If you're after a free NEC based antenna modeler today, 4NEC2 is a similar program that is already free. There is also the recently released and more modern CENOS, which is free for hobbyist use.

The EZNEC Software

The KiwiSDR Backdoor Situation

Since it's announcement in early 2016 we've posted many times about the KiwiSDR, a 14-bit wideband RX only HF software defined radio created by John Seamons (ZL/KF6VO). The KiwiSDR has up to 32 MHz of bandwidth, so it can receive the entire 10 kHz - 30 MHz VLF/LF/MW/HF spectrum all at once.

Compared to most other SDRs the KiwiSDR is a little different as it is designed to be used as a public web based SDR, meaning that KiwiSDR owners can optionally share their KiwiSDR online with anyone who wants to connect to it. The public functionality allows for some interesting distributed applications, such as TDoA direction finding, which allows users to pinpoint the location of unknown HF transmissions such as numbers stations.

In order to implement this online capability, the KiwiSDR runs custom open source software on a Beaglebone single board computer which connects to your home network. Recently there has been vocal concern about a security flaw in the software which could allow hackers to access the KiwiSDR. The flaw stems from the fact that the KiwiSDR has 'backdoor' remote admin access that allows the KiwiSDR creator to log in to the device and troubleshoot or make configuration changes if required. This backdoor has been public knowledge in the KiwiSDR forums since 2017, although not advertised and explicit consent to have it active and used was not required.

The intent of the backdoor is of course not malicious, instead rather intended as an easy way to help the creator help customers with configuration problems. However, as KiwiSDR owner Mark Jessop notes, the KiwiSDR operates in HTTP only, sending the admin master password in the clear. And as KiwiSDR owner and security researcher @xssfox demonstrates, the admin page gives full root console access to the Beaglebone. These flaws could allow a malicious party to take over the Beaglebone, install any software and perhaps work their way onto other networked devices. Another tweet from xssfox implies that the password hashes are crackable, allowing the main admin password to be easily revealed.

Creator John Seamons has already released a patch to disable the admin access, and as of the time of this article 540 out of 600 public KiwiSDRs have already been auto-updated. Owners of KiwiSDR clones should seek out updates from the cloner.

It is clear that the KiwiSDR is a passion project from John who has dedicated much of his time and energy to consistently improving the technical RF engineering side of the device and software. However we live in an age where malicious hacking of devices is becoming more common, so anyone releasing products and software that network with the internet should be reminded that they have a responsibility to also dedicate time to ensuring security.

John has reached out to us in advance and noted that he currently cannot yet comment publicly on this topic due to legal advice.

The KiwiSDR
The KiwiSDR

Airspy Summer Promo: 20% Off Airspy Products Including YouLoop in our Store

Airspy is currently holding a 20% off summer promotion which runs from June 28th until Julty 4th 2021. The sale is active at all participating resellers, which includes our own store where we have the YouLoop on sale for US$27.96 including free shipping to most countries in the world, instead of the usual US$34.95. Please note that due to new EU VAT collection laws, EU customers must purchase the discounted YouLoop from our eBay or Aliexpress stores. 

The YouLoop is a low cost passive loop antenna for HF and VHF. It is based on the Möbius loop design which results in a high degree of noise cancelling. However the main drawback is that it is a non-resonant design, which means that it works best when used with ultra sensitive receivers like the Airspy HF+ Discovery. 

Some good reviews include the YouTube videos done by Frugal Radio where he reviews HF reception and VLF & LF reception with an Airspy HF+, and later tests it with an RTL-SDR Blog V3 using direct sampling. Techminds also has an excellent review on his YouTube channel. We also have a product release overview on this post from March 2020.

Crimean Resident Arrested under Accusation of Spying for Ukraine with RTL-SDR Dongles

Back in early 2014 Crimea was annexed from the Ukraine by Russian forces. Recently we've heard news that a Crimean resident was arrested by the Russian Federal Security Service under the suspicion of being a Ukrainian informant who was intending to transfer, or was transferring military data abroad using RTL-SDRs.

A video of the arrest has been uploaded to YouTube, and RTL-SDR dongles running with the Airspy SDR# software on his laptop can clearly be seen as having been photographed. The photos of the SDR# screen appear to show that he was monitoring the commercial aviation band with a scanner plugin.

The YouTube description is translated below:

Today it was reported about the arrest of a Crimean resident, either intending to transfer, or transferring military data abroad.

The FSB has published footage of the arrest. The time on the laptop caught on the video during the search of housing 07:40 date 06/22/21. The laptop is turned on, the AIRSPY radio frequency scanning program is running, the laptop is in the dust - only traces of pressing some keys are visible, and the touchpad was not used. There are many icons in the room, books on radio engineering, a Ukrainian flag, aircraft models, several pennants "Tavria 1958", an ICOM IC-R6 radio, maps.

The detainee transferred the information received to Ukraine on one basis, collected it on the other and intended to transfer it.

The court sent the man to the pre-trial detention center for 2 months. If his guilt is proven, then high treason "shines" and does not shine to see the will for 25 years.

According to an article on RadioFreeEurope, the man was detained as he was "collecting data on the flights of Russian military planes for Ukrainian intelligence".

It is unclear if the man was knowingly providing intelligence services, or is simply an aviation hobbyist caught up in politics. If anyone has more information about his story, please let us know in the comments.

UPDATE 29 June 2021: More information on the story at this link.

Украинский осведомитель был футбольным фаном. Болел за «Таврию»

Crimean resident arrested for using RTL-SDRs to monitor the airband
Commercial Aviation Frequencies Monitored

This is a reminder to those in politically dangerous situations to take care when using SDRs. In the past we have seen a Slovenian researcher almost jailed for performing University research with an RTL-SDR, a UN expert arrested for possessing an RTL-SDR in Tunisia, and SDRs come under fire when Trump tweeted a now-debunked conspiracy theory on how an RTL-SDR was being used as a close range scanner by the black lives matter protestor who was shoved to the ground on video by Buffalo police.

CaribouLite: A 30-6000 MHz 13-bit 4MHz SDR HAT for the Raspberry Pi

Thank you to David for submitting news about his company Caribou Labs' new product called "CaribouLite" which will be a software defined radio HAT for the Raspberry Pi. The product is currently in the pre-launch stage over on Crowd Funding platform CrowdSupply and you can sign up for future updates on the release. David writes:

I'd like to inform you of a product we have developed called CaribouLite board, which is essentially a Raspberry Pi HAT that enabled up to 6GHz SDR capabilities Tx and Rx, and an additional TxRx Sub 1GHz channel.

It uses Microchip's modem AT86RF215 as an I/Q ADC, DAC and frequency conversion is done using Qorvo's RFFC5072 IC. An FPGA (ICE40) is used to stream data packets (I/Q @ 13 bit x2 / sample) back and forth between the Raspberry Pi and the Modem, over an interesting fast interface called SMI.

I think this project brings new ideas to the table and would be interesting to the SDR community.

The use of the SMI interface is an interesting idea and not something we see utilized often as apparently the official documentation is sparse and poor. But David notes how it allows for up to 500Mbit/s of data to be exchanged between the FPGA and Raspberry Pi, although the true throughput depends on the specific Raspberry Pi model used. Regardless the SMI data rate is more than enough for the 120 MBit/s required by the two streams of 13-bit IQ data that the CaribouLite generates.

The campaign also notes that the sample rate is 4 MSPS, with 4 MHz bandwidth, and up to 14 dBm of transmit power is possible. They also note that they are planning to release a wide range of library code that allows for use cases such as wide range spectrum analysis, a signal / protocol generator, an analog / digital DAB+ receiver, an ADS-B receiver and more.

The software and hardware design is also fully open source and available on GitHub.

The CaribouLite SDR HAT mounted on a Raspberry Pi Zero

Avoiding Fake RTL-SDR Blog V3 Clones + 2021 Supply Chain Updates

As a follow on to the previous post on fake SDRplay units, we also wanted to provide some guidance on fake RTL-SDR Blog V3 clones which are on the market. We are starting to receive an increase in support requests for fake RTL-SDR Blog V3 units. Please be aware that we cannot support these devices, and most of them are missing key features like the bias tee and the TCXO despite advertising these features on the listing and writing on the dongle body. Also as mentioned below a good majority of them appear to have a defect and poor performance.

Please check our store at for our official stores on Amazon, eBay, Aliexpress and this site. We also have links on our store to our official local resellers.

We note that we tested a few of the "RTL.SDR" clones, and all had a defect causing very strange distorted spectrums where the signals where wider than they should be, and some units introduced a mysterious high pitched whine into every signal.

Spectrum from clone
Spectrum of an original RTL-SDR Blog V3

To be clear, different brands of RTL-SDR are perfectly fine - no one owns the RTL-SDR hardware concept and we are not any more "official" than any other brand (although we believe we were the first to start designing and producing significantly improved units and the first to design in a factory fitted TCXO, SMA connector, bias tee, thermal pad, and a redesigned PCB for lower noise and less spurs).

However, these clones shown in the image above can be considered a sort of scam as they attempt to trick buyers into believing that they are purchasing our RTL-SDR Blog V3 units with false advertising and by copying the enclosure design, when in fact the PCB inside is something inferior.

2021 Supply Chain Updates

As many of you may know the world is currently dealing with a major shortage of many electronics parts so we wanted to provide an update on the supply chain for the RTL-SDR Blog V3.

In particular, the world is very short on temperature compensated oscillators (TCXO's), a critical component used in our units to ensure frequency stability. The TCXO shortage is actually much worse than other components as AKM, the Japanese semiconductor factory that produces a critical component for making TCXOs burned down late last year. There are alternative suppliers, however their pricing is many multiples higher, and they are also inundated with orders increasing lead times.

We believe that we have enough TCXO stock in storage to last us several more months, however we may run into a shortage in the later months of this year. After we expend our current TCXO stock, we expect to have TCXO again around December, with more RTL-SDRs being ready by January 2022. We want people to be aware, as during these months of no stock more clones may appear on the market. Most clones do not use TCXOs, and hence have poor frequency stability.

Also on a related note our Amazon stock levels may be a little spotty throughout this year as there are currently often delays with shipping and the ports.

We also note that other products that we resell on our store such as the FlightAware Prostick Plus and NanoVNA V2+ are also experiencing supply issues, and may not have stock for a while. Production of some of our other products like the L-band Patch are also delayed due to shortages. 

Due to the shortages component prices are also significantly increasing, and you may notice an increase in RTL-SDR pricing from us and competitors too. We hope that we will be able to reduce our pricing again once the global shortage is over, most likely around early next year.

Freenode ##rtlsdr IRC Channel Moving to Libera

The ##rtlsdr IRC Freenode chat channel will be moving to However ##rtlsdr admins note that the Freenode channel will remain open for now. This move is in wake of the recent takeover drama surrounding Freenode, and the resignation of the majority of Freenode staff.

The ##rtlsdr IRC channel is where many RTL-SDR, software defined radio and RF enthusiasts hang out. You can join and idle with any IRC client, or a web client is available at

A discussion about the move has also been opened on Reddit /r/rtlsdr.

Many other related project channels such as #gnuradio are also moving over to Libera.

Smart Meter Hacking Hack Chat to be held April 14 Noon Pacific Time

In the last post from a couple of days ago we posted about RECESSIM's YouTube series about smart meter hacking. Hackaday have noted that Hash, the security researcher behind the RECESSIM channel will be hosting a Hack Chat on April 14 noon pacific time. If you're unfamiliar with them, hack chats are live chat events where you can chat directly with an expert on a particular topic.

That electrical meter on the side of your house might not look like it, but it's pretty packed with technology. What was once a simple electromechanical device that a human would have to read in person is now a node on a far-flung network. Not only does your meter tote up the amount of electricity you use, but it also talks to other meters in the neighborhood, sending data skipping across town to routers that you might never have noticed as it makes its way back to the utility. And the smartest of smart meters not only know how much electricity you're using, but they can also tease information about which appliances are being used simply by monitoring patterns of usage.

While all this sounds great for utility companies, what does it mean for the customers? What are the implications of having a network of smart meters all talking to each other wirelessly? Are these devices vulnerable to attack? Have they been engineered to be as difficult to exploit as something should be when it's designed to be in service for 15 years or more?

These questions and more burn within Hash, a hardware hacker and security researcher who runs the RECESSIM reverse-engineering wiki. He's been inside a smart meter or two and has shared a lot of what he has learned on the wiki and with some in-depth Smart Meter Hacking videos. He'll stop by the Hack Chat to discuss what he's learned about the internals of smart meters, how they work, and where they may be vulnerable to attack.