Trees as Conductors: Measuring Natural Impacts on HF Radio

An article published on QEX details measurements of tree conductivity and permittivity at HF frequencies, addressing a long-debated topic in amateur radio. N6LF conducted experimental impedance measurements on Douglas fir and maple trees using a vector network analyzer with rings of nails inserted into tree trunks. Results showed that tree conductivity increases with frequency while relative permittivity decreases, similar to soil characteristics. Measured conductivity ranged from 0.06 to 0.4 S/m at 10 MHz, aligning with values used in previous research. These findings validate that NEC modeling can reliably estimate trees' substantial impact on HF antenna performance.

Media Article - https://www.dxzone.com/dx36327/trees-as-conductors-measuring-natural-impacts-on-hf-radio.html

New Book Featuring 15 Portable Antennas, Beautifully Rendered

Join Salty Walt, K4OGO, of the Coastal Waves & Wires YouTube channel, where all the action happens — right on the beach! Ham radio adventure awaits with 15 portable antenna designs. Walt begins with the basics of setting up a quarter- or half-wave vertical, but then draws readers into more experimental designs like his own Coastal 20 or an end-fed vertical made with a Slinky®. Each sketch, reproduced from Walt’s own design notebook, provides wire lengths and practical attachment information.

In addition to his sketches, Walt offers portable construction and operating tips, and just enough about counterpoise wires and ground to get you making contacts in no time. This isn’t a heavy-duty treatise on maximally efficient antennas, it’s a book for the “true amateur,” the ham who gets out by the waves with a radio to see what they can make happen. Like Walt says, “This isn’t the Mozart of antenna books, it’s the Jimmy Buffett.”

Walt pairs each antenna with a dining spot you can try, whether you’re on Waimea Bay in Kauai, deep in the Big Easy’s French Quarter, or on the long Atlantic stretch of Nags Head, North Carolina. He guides you to the best chowders, fish tacos, crab legs, and more, all while building antennas, making contacts, and soaking up some coastal rays.

Salty Walt’s Portable Antenna Sketchbook is now shipping. Order from the ARRL online store or find an ARRL publication dealer; ARRL Item No. 2226, ISBN: 978-1-62595-222-6, $25.95 retail, member price $22.95.

ARRL Teachers Institute Application Deadline

Applicants for the summer 2025 sessions of the ARRL Teachers Institute on Wireless Technology must apply by April 30 to be considered. The application process is straightforward. Interested educators can find the web form at http://www.arrl.org/ti. ARRL covers all the costs of the TI, including travel, but there is a $100 application fee if the teacher is accepted.

The Teachers Institutes are a productive week for those who attend. The program is designed to not just introduce amateur radio to classrooms, but more importantly to enable teachers to build content around wireless technology of all kinds into their lessons. 

Part of ARRL’s mission is to inspire the next generation of radio amateurs, but through this program the ripple effects spread into all things related to radio engineering. ARRL Education and Learning Manager Steve Goodgame, K5ATA, said teachers leave fired up about radio. “To see the excitement these educators have after a TI is very rewarding. We see success when that enthusiasm ripples out across communities, and we want to reach more teachers than ever before,” said Goodgame. 

ARRL has expanded the program for 2025, doing sessions around the country. The first field session was held on Staten Island in New York City. Other regions are planned for 2025. 

ARRL Teachers Institute Application - http://www.arrl.org/ti