Category: Antennas

Using an RTL-SDR Dongle to Receive Pictures from the ISS

Over on YouTube we've seen a good video from channel Ham Radio DX where presenter Hayden shows how to use an RTL-SDR to receive slow scan television (SSTV) images from the International Space Station (ISS). Often the ISS will transmit SSTV images down to earth on the VHF 2 meter bands as part of an event. With an RTL-SDR and simple antenna it's possible to receive those images.

In the video Hayden discusses the SSTV transmission, and demonstrates some SSTV decoding happening in real time as the ISS passes over his location. If you're looking to get started in ISS SSTV reception, this is a good video to get an idea of what's involved. He finishes the video with some useful tips for reception.

Using a RTL SDR Dongle to receive pictures from the ISS! | Software Defined Radio

Frugal Radio: Turning Scrap Wire into an Effective HF Dipole

In this weeks video Rob from his Frugal Radio YouTube channel shows us how he's turned an old piece of scrap electrical extension cord into an effective HF antenna for his Airspy HF+ SDR. The scrap wire is combined with a US$15 NooElec 9:1 balun which helps improve the impedance match of the antenna. He then stretches the dipole out through his backyard and then hooks it up to his Airspy HF+.

The results show good reception across the 20m, 80m, 40m amateur radio bands, as well as on HF ATC aircraft communications, US coast guard weather information broadcasts and the AM broadcast band.

I made an HF Dipole for free! Reception was good on my AirSpy HF+ Discovery SDR!

Frugal Radio: How To Decode L band Satellite ACARS and CPDLC messages with JAERO and your SDR

In the latest episode of his YouTube series on Aviation monitoring Rob explores how to decode L-band satellite ACARS (Aircraft Communication Addressing and Reporting System) and CPDLC (Controller Pilot Data Link Communications) messages using JAERO, an SDR like an RTL-SDR, and a appropriate L-band antenna such as our RTL-SDR Blog Active L-Band Patch (currently out of stock).

In the video Rob shows examples of what you might receive such as CPDLC ATC instructions, digital ATIS information, arrival information and suggested landing data configuration instructions. He goes on to show satellite coverage maps, what hardware is required to receive these signals, and finally how to setup the receiving and decoding software.

How To Decode L band Satellite ACARS and CPDLC messages with JAERO and your SDR

Frugal Radio: A Review of the NooElec Inmarsat Patch Antenna Bundle

In his latest video Rob from Frugal Radio has reviewed the NooElec Inmarsat Patch Antenna Bundle. The US$79.95 bundle includes a PCB patch antenna, Inmarsat SAWBird LNA, SMA DC Block, SMA Barrel adapter and SMA pigtail. In the video Rob tests the bundle out on various AERO signals using the JAERO software, before moving on to compare the bundle with our own RTL-SDR Blog Active L-Band Patch antenna. The comparison results show that our $49.95 L-band antenna is better by about 5-6dB in SNR.

Our RTL-SDR Blog Active L-Band Patch antenna set is available on our store. However, please note that this antenna is currently in short supply due to the global electronics supply chain shortage. We expect to be sold out within a few days but we are aiming to be able to restock within 1-2 months from now.

Review : NooElec L Band Inmarsat Patch Antenna Bundle

A Hi-Z to 50 Ohm Impedance Matching Transformer for Improving HF/SW Reception

Thank you to Mitsunobu for writing in and sharing news about the release of his new product which is a Hi-Z (high impedance) to 50 Ohm matching transformer. This transformer allows you to use small antennas such as short telescopic whips for HF/SW reception on software defined radios.

Generally for HF reception you would want to use a full sized antenna, which can be many meters long and certainly not portable. However, by using an high impedance transformer it becomes possible to use smaller portable antennas. Reception with a small antenna and transformer will still be suboptimal compared to a full sized HF antenna, however, if the signals are strong enough the transformer will allow you to receive them decently.

In the tests shown on his blog (in Japanese, use Google Translate) he shows how the transformer adapter can be connected to a small telescopic whip and Malachite DSP SDR for portable use. Later he also shows how the adapter can make our Dipole Kit antenna work well for HF on a RTL-SDR Blog V3 with direct sampling.  

The product is only available via Amazon in Japan. However, Mitsunobu notes that offers international shipping. He offers the transformer by itself, and a version including a short telescopic whip antenna.

Hi-Z to 50 Ohm Antenna Transformer for HF/SWL

Building an Automated NOAA and Meteor Weather Satellite Image Collector with RTL-SDR

Over on his YouTube channel saveitforparts has uploaded a video showing how he has built an automated weather satellite image collector for the NOAA APT and Meteor M2 LRPT satellites. The video shows a time lapse of him building a QFH antenna, and how he's mounted a Raspberry Pi and RTL-SDR inside a waterproof enclosure attached to the antenna mast. He goes on to show how he's automating the system with the Raspberry-NOAA V2 software

Automated Home Weather Station (Satellite Image Collector)

CENOS Launches Affordable And Easy-to-use Simulation Software For Antenna Design

Over the past few months we have posted a few times about the beta of CENOS, a new antenna modelling and simulation design package. Recently CENOS has exited it's beta testing phase, and they have put out a press release about the first release.

Of most importance is that the software is affordable for hobbyist's, with a 10-day free trial and subscription price of €20 (US$25) per month for hobbyist use (no live engineering support).

Electromagnetics simulation software company CENOS (Riga, Latvia) continues on its mission to democratize simulation software by releasing its newest application designed for radio frequency and antenna design engineers. CENOS released its first electromagnetics simulation software focused on the induction heating applications in 2017 and it proved to be a success - mainly because of the simple and straightforward user experience and the specialization and focus on a single industry. After a year of development and testing in close cooperation with its avid beta-tester community, the Antenna Design simulation software was finally released for public use at the end of April, 2021.

CENOS Antenna Design is an intuitive FEM-based software that helps engineers to speed up RF antenna design, it solves Maxwell’s equations directly with no simplifications or limitations. Therefore, the results provided by CENOS are accurate for wide ranges of geometries and antennas, including very complex geometries. For instance, the software is good for high Q, multi-port simulations with arbitrary 3D structures. It is specialized for the simulation of microstrip- and wire-type antennas that include various geometries (fractal, helix, horn, loop, slot, patch, spiral, and others), as well as dipole and monopole antennas.

CENOS co-founder Dr. phys. Mihails Scepanskis: “Two years ago we launched a specialized induction heating simulation software to cover the growing demand in the SME sector - smaller equipment manufacturers, tooling shops, and production plants. Following the success in the low-frequency applications, we decided to move to the microwaves with the same mission - to democratize the simulation software, make it accessible for every engineer. I believe, it is an awkward situation in the market - engineers have to choose either to pay tons of money for enterprise-type generic simulation packages to utilize just a fraction of their functionality or to use over-simplified 1D approximations with the hobbyist-level software. With CENOS we have leveraged the power of open-source algorithms to break the status quo - to deliver a full-functionality FEM software for price-sensitive business users and individuals.”

CENOS Antenna Design is free to try for 10 days, after which the users can choose from the two subscription plans - for an individual or business use, starting from 20 euros per month ($25). The business version includes the features that help to automate and speed up simulation processes and has more integrations with the existing software and, most importantly, it has a live customer support through the chat and video calls. More features are planned to be added in 2021 and thus the prices may be increased over time, so now it is a good moment to subscribe and get all the future updates for a lower price.

The company name CENOS stands for “Connecting ENgineering Open Source” highlighting the new software approach they invented. It is a platform that connects the best of community-driven open-source algorithms into one seamless user experience and since it is a desktop software - the data do not leave the owner’s computer. CENOS was founded in 2017 by 3 PhDs in physics and mathematics who committed themselves to the democratization of the simulation software by making it easy, affordable, and secure for every engineer. CENOS is a startup, funded by the leading San Francisco early-stage investor ‘500 Startups’, the leading B2B European accelerator Startup Wise Guys, and the cohort of the Baltic business angels.

CENOS offers a 10-day trial, follow the link to sign up:

CENOS Screenshots

KrakenSDR: Passive Radar Demonstration

KrakenSDR is a 5-tuner coherent software defined radio based on RTL-SDR. It is the successor to the KerberosSDR and will be crowdfunded on Crowd Supply in a couple of months time. Please sign up to the KrakenSDR Crowd Supply mailing list to be notified as soon as the campaign begins.

The KrakenSDR (prototype - enclosure may change slightly)

Passive Radar uses existing FM, TV or mobile phone transmitters. The signal from these transmitters reflects off objects such as road vehicles and aircraft. By using two antennas on two receive channels, and an algorithm to compare the reflected signal against a clean reference copy of the actual signal, we can achieve a radar like display of bi-static range vs doppler speed.

In this test KrakenSDR is used as a two antenna passive radar system. The reference antenna points towards a horizontally polarized 620 MHz DVB-T transmitter, and the surveillance antenna points towards an Airport.

Passive Radar setup with two TV Yagis

Reflections of aircraft and road vehicles can be seen on the map as red dots/trails. Notice how we can also determine the overall neighborhood activity of road vehicles as we pointed out in a previous KerberosSDR post.

Of note is that we've placed the surveillance antenna in a vertically polarized configuration. With passive radar you want to keep the reference signal out of the surveillance channel, as ideally the surveillance channel only receives the reflections. Using the surveillance antenna in vertical polarization achieves 20dB attenuation of the horizontally polarized DVB-T signal. The reflections are assumed to be randomly polarized, so the vertically polarized antenna should pick up the reflection just the same no matter what polarization is used. This scheme woks especially well in our setup as the angle between the reference transmitter and target reflected objects is small.

This test uses the older KerberosSDR code (slightly modified to allow for trails), however new passive radar code is being worked on for the new KrakenSDR code base which will be released later this year. We expect the new code to also be able to make use of GPU accelerated CUDA hardware, such as the NVIDIA Jetson. This will allow for a much faster update rate and/or more processing gain.

The new KrakenSDR code will also try to make use of the additional three unused channels. With these extra channels we should be able to add a direction finding array that will help to plot on a map the actual location and elevation of the reflections.

KrakenSDR Passive Radar Demonstration 1