Science & Nature
1439 sites
Subcategories:
- Astronomy & Space (396)
- Chemistry (8)
- Earth Sciences (26)
- Biology (79)
- Physics (30)
- Mathematics (59)
- Weather & Climate (104)
- Amateur Radio (682)
- Electronics (47)
https://erau.ee/et
The Estonian Amateur Radio Union (ERAÜ) is the official national organization for ham radio operators in Estonia, a member of IARU since 1938. The site offers extensive resources including contest calendars, repeater and beacon info, exam guidance, QSL services, SDR links, and club directories, all available in Estonian and English.
https://f4iha.fr/
The blog of Olivier (F4IHA), a French amateur radio enthusiast who documents his homebrew radio projects including low-power QRPP transmitters, VFOs, antenna tuners, and fox-hunting modules built with Arduinos and components costing under 30 euros. Posts cover schematics, PCB design in KiCad, measurements, and hands-on construction with detailed technical write-ups that make it a great resource for DIY radio builders.
http://w0crc.org/
The Crow River Amateur Radio Club is a regional ham radio club with pages covering repeaters, reflectors, and links to ARRL resources. The site serves as a hub for local amateur radio operators in the Crow River area, offering member resources and monitoring tools.
https://umass.edu/rso/hamradio
The official homepage of the UMASS Amateur Radio Club (callsign W1PUO), a student-run club at the University of Massachusetts Amherst founded in 1996 by College of Engineering students. The club offers a shared radio shack, licensing classes for prospective hams, and public service events open to all five-college university students, faculty, staff, and their families.
https://ucolick.org/~sla/leapsecs/deltat.html
Steve Allen's detailed reference site on the history and technical implications of leap seconds, delta time, and precision time scales used in astronomy and timekeeping. It features plots, tables, historical data, and analysis of the ongoing ITU-R debate over whether to abandon leap seconds from UTC.
http://nmia.com/~roberts/robert.html
Robert Smathers maintains this personal hub dedicated to TVRO (Television Receive Only) satellite reception, featuring links, schedules, mail lists, newsgroups, and dealer resources for satellite hobbyists. The site also touches on visual satellite observing and space topics, making it a useful reference point for backyard dish enthusiasts.
https://sandra.radio/
SANDRA (San Diego Repeater Association) is a 501(c)(4) non-profit amateur radio club based in San Diego, California, serving local ham radio operators with repeater listings, digital services, and club resources. The site offers member information, net schedules, a mailing list, meeting recordings, and operating guidelines for the regional amateur radio community.
http://sm0vpo.altervista.org/
Harry Lythall (SM0VPO/G4VVJ) shares an extensive collection of homebrew amateur radio construction projects, covering everything from QRP transmitters and receivers to circuit boards, oscillators, and RF amplifiers. The site is a treasure trove for hands-on ham radio enthusiasts, packed with schematics, datasheets, calculators, and practical guides for building your own radio equipment.
https://rutar.org/
Alex Rutar is a mathematics postdoctoral researcher specializing in fractal geometry, dynamical systems, and dimension theory, with affiliations at the University of Jyväskylä and a PhD from the University of St Andrews. His site serves as an academic hub linking to his publications, expository writing, CV, and open-source developer tools built around LaTeX and terminal utilities.
http://arrl.org/
The American Radio Relay League (ARRL) is the official national membership organization for amateur radio operators in the United States, offering news, licensing resources, regulatory advocacy, and publications like QST magazine. A comprehensive hub for ham radio enthusiasts at every level, the site covers contests, digital networking, solar updates relevant to propagation, and community events.