Category: Antennas

SignalsEverywhere: Decoding HF WEFAX Weather Fax with an Airspy HF+ Discovery SDR

Over on YouTube Sarah is back this week with a new video on her channel SignalsEverywhere. In this video she shows how to decode HF WEFAX (weather fax) images using an Airspy HF+ Discovery software defined radio with a YouLoop antenna. HF weather faxes are daily weather chart images transmitted as an analogue signal over the HF bands by coastal stations. They are mostly used by ships at sea.

First Sarah shows where to find a lists of WEFAX frequencies and schedules for her area, and then goes on to demonstrate a WEFAX signal being received and decoded using SDR#, VB-Audio Cable and the FLDIGI decoder.

Decoding HF WEFAX Weather Fax with SDR Software Defined Radio | Airspy HF Discovery

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

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 Amazon.jp 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)