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PA3FWM
pa3fwm.nl · Personal blog · on HN since 2018
PA3FWM is a Dutch radio engineer who writes about software defined radio, antennas, microwave CAD, and electronics.
What HN saysHN commenters praise the site as full of gems, especially the WebSDR notes, and recommend its antenna technotes and the Puff simulator.
16HN people shared it
9linked it in comments
8stories submitted
419story points
9 months agolast shared
2018people per year2026
Most-shared posts
- 1Nixie-clock using neon lamps as logic (2017)3 people · 147 points · first shared 2018 · 16 comments on HN
- 2PA3FWM's Software Defined Radio2 people · 4 points · first shared 2024 · discussion on HN
- 3Puff microwave CAD software on Linux2 people · 2 points · first shared 2021 · discussion on HN
- 4The Polyphase Mixer (2022)2 people · 1 points · first shared 2023 · discussion on HN
- 5Tn072 people · first shared 2020
- 6Oliver Heaviside and the theory of transmission lines (2021)1 people · 264 points · first shared 2025 · 71 comments on HN
- 7Quartz Crystals1 people · 1 points · first shared 2026 · discussion on HN
- 8Modulation1 people · first shared 2020
- 9Avreth1 people · first shared 2019
- 10Tn09b1 people · first shared 2024
- 11Tn27a voltmeter1 people · first shared 2023
- 12Rscw1 people · first shared 2020
What HN people wrote when they linked it
jacquesm · 2026-02-09
Nice to see this get more love, I had a fun time going through that site, there are lots of gems there.
For instance:
https://www.pa3fwm.nl/projects/sdr/
The longer you read, the more amazed you will be.
buescher · 2024-05-07
The PUFF microwave simulator is a favorite of mine and quick enough for what it is. Not a modern UX flow though.
https://www.pa3fwm.nl/software/puff/
CamperBob2 · 2025-09-17
For HF, look at the technical articles by PA3WFM for the WebSDR at utwente.nl, especially this one: https://www.pa3fwm.nl/technotes/tn07.html
TL,DR: you probably don't want a random wire for HF reception, but either an E-field whip antenna like that one, or an H-field loop which will likely be larger and more expensive, but will have useful directional properties that the whip will not.
wizzwizz4 · 2024-12-23
> Logically speaking, if the wavelength that we use for forms of radio communication make it to earth, then we would need to transmit at a higher power to overcome that background noise.
If this were true, GPS wouldn't work. It's entirely possible to communicate below the noise floor. See https://www.pa3fwm.nl/technotes/tn09b.html for a mathematical analysis.
flashback2199 · 2023-10-22
Counterpoint: The IC at the heart of basically every cheap meter is a clone of the IC in an old Fluke DMM
https://www.pa3fwm.nl/technotes/tn27a-voltmeter.html
Honestly I would say cheap out on the DMM and splurge for a good oscilloscope, you get much farther with that.
But, I'm someone who doesn't do high voltage much, or really at all.
mikewarot · 2023-02-24
Polyphase Tayloe mixers[1] already balance out up to 21st harmonics in practice.
It would be interesting to see actual details at least linked to in these type of press releases.
[1] https://www.pa3fwm.nl/technotes/tn17c.html
threeme3 · 2020-11-18
This is a javascript tool that gives insight in what modulation does on the I/Q constellation: https://pa3fwm.nl/tools/modulation.html
jhallenworld · 2020-03-15
The MiniWhip antenna this thing uses is interesting all on its own, see:
http://www.pa3fwm.nl/technotes/tn07.html
I see they are widely available to buy.
tyingq · 2019-12-15
On Ethernet, there are a couple of different folks that have successfully bit banged 10mbit Ethernet with an AVR. That would be a pretty good way to learn. Though 10mbit is Manchester encoded...nothing faster is. Also, watch out for POE. One example: http://www.pa3fwm.nl/projects/avreth/