This article details a fascinating project where a researcher successfully used signals from the NISAR radar-imaging satellite to create a passive radar system. By utilizing the satellite's L-band chirp signal, reflected off the landscape, and comparing it to a direct signal, a topographical image could be generated. The setup involved using GNSS antennas and an SDR (Software Defined Radio) with a Raspberry Pi to record and process the signals. While not producing high-resolution images, the experiment successfully demonstrated the feasibility of using satellite signals for passive radar, even with relatively simple and inexpensive equipment.
The NanoFarfield is a portable far-field measurement system for low-cost vector network analyzers like the NanoVNA and LiteVNA. It features a motorized rotation platform, amplifier, RF limiter, and measurement software to produce accurate radiation patterns and gain measurements. It's designed to be affordable, reproducible, and accessible for RF engineers, researchers, and makers.
Five years after the collapse of the Arecibo Telescope, a radio telescope is back online. The signal is back.
A technical overview of intercepting and decoding satellite communications, detailing hardware, software, and techniques used for signal acquisition and decryption.
An IETF draft proposes allocating the 44::/16 IPv6 block (about 2^112 addresses) to the amateur radio community, echoing the historic 44/8 IPv4 allocation, and raises questions about internet governance and policy.
The ITU‑R Recommendation P.833‑2 provides guidance on estimating radio‑wave attenuation caused by vegetation for frequencies between 30 MHz and 60 GHz. Because foliage conditions vary widely and experimental data are limited, the recommendation offers separate models for different frequency bands and path geometries. For a terrestrial link with one end inside a woodland, the extra loss is expressed using two parameters: the specific attenuation rate γ (dB / m) that describes short‑range scattering loss, and a maximum attenuation Am that caps the total excess loss due to additional mechanisms such as surface‑wave propagation and forward scattering. The excess attenuation for a path length d inside the vegetation is given by Aev = Am 1 – exp(–d γ / Am) » . This formulation allows engineers to calculate the additional loss when a transmitter or receiver is located within dense vegetation.
Information about Meshtastic, an open-source, decentralized, off-grid mesh network, and the MDARC's involvement with it, including node locations and configurations.
Thomas Witherspoon recounts his renewed appreciation for the Elecraft K2 kit radio, highlighting its enduring appeal, build quality, and performance in both shack and field operations as of 2025.
* **Nostalgic Rediscovery:** Thomas rekindled his love for the K2 after using it on field activations, appreciating its superior audio quality and low noise floor, which make it a pleasure to operate.
* **Kit Radio Advantages and Challenges:** The K2’s status as a kit radio offers excellent serviceability, repairability, and long-term support, though build quality can vary and requires careful inspection when purchasing used.
* **Enduring Value and Legacy:** Despite being over two decades old, the K2 remains a highly satisfying and reliable transceiver, valued by operators for its simplicity, craftsmanship, and suitability for both QRP and QRO operations.
* **Nostalgic Rediscovery:** Thomas rekindled his love for the K2 after using it on field activations, appreciating its superior audio quality and low noise floor, which make it a pleasure to operate.
* **Kit Radio Advantages and Challenges:** The K2’s status as a kit radio offers excellent serviceability, repairability, and long-term support, though build quality can vary and requires careful inspection when purchasing used.
* **Enduring Value and Legacy:** Despite being over two decades old, the K2 remains a highly satisfying and reliable transceiver, valued by operators for its simplicity, craftsmanship, and suitability for both QRP and QRO operations.
HiR Information Report - Personal page of ax0n, featuring projects, blog entries, social media links, and professional background in cybersecurity and technology.
Edward F. "Ed" Hare, Jr., W1RFI, a long-time ARRL Lab engineer, passed away on October 10, 2025, at the age of 75. He was a dedicated ham radio operator, RFI expert, and contributor to ARRL advocacy efforts.
