Antennas, experiments, engineering and other articles of interest to radio folks.
Use this 2 second rule to measure when your driving is distracted enough to be of concern to you and others. Holding a microphone is fine, but other aspects of our mobile radios deserve scrutiny.
A simple S21 test reveals conductive shields do not change the behavior or ability of a ferrite to perform the role of common-mode rf current choke.
Careful selection of quality probes joined with the Raspberry Pi offerings yields a wireless E and H field sensor for accurate antenna analysis.
The Raspberry Pi Zero brings nearly off the shelf gear to the task of generating an RF test signal from a completely wireless, small, self powered device about the size of a D cell.
Simulations suggest end-fed and center-fed half-wave dipoles share sensitivity to various feedline lengths, but in differing and manageable ways.
I take a moment to document observed differences between end-fed antenna autotransformers with and without ferrite core materials with a focus on the reactance compensation.
A NEC model that includes the transformer helix helps demystify the end-fed half-wave (EFHW) dipole antenna using the autotransformer as impedance converter.
Measurements and analysis suggest why quarter-wave stubs fail to completely isolate radiator conductors on multi-band antennas including the popular rollup 2m/440 J-Pole products. Possible improvements are shown.
Tests suggest transmission line decoupling stubs are not immune to the conductor past the stub.
Those opposed to Winlink are attempting to hold removal of the 300 baud HF data limitation hostage.
You would think the world of RF connectors of the pedigree of the “N” would rigorously follow the dictates of the standards that define them. Thankfully most do, but exceptions arise and here is one such example of why it pays to “trust, but verify.”
Measurements reveal the effects of common mode current on the J antenna.
Does one really need to upgrade the antenna that came with your HT? Presented are EIRP measurements of various aftermarket HT aerials to help understand the trade space.
A closer look at type 61 ferrite material in various configurations for RG58 reveals the benefits and insufficiencies of chokes in series.
Learning more about several ferrite compositions from the Fair-Rite manufacturer including where to buy them.
I measure one example of a ferrite coax choke for response over frequency to understand its suitability for VHF and UHF.
EIRP measurements of the 2m end-fed half-wave HT antenna from MFJ aids understanding a dipole is a dipole no matter where you feed it.
Thanks to a spiffy new Airspy HF+ SDR receiver I can scratch listening to WWVB off the bucket list.
My MFJ-259 HF/VHF SWR Analyzer required yet another repair to its internal battery holders.
The National Institute of Standards and Technology appears to have the time and frequency broadcast stations on the chopping block given the info contained in their 2019 budget proposal. This is what I wrote to my senator and congressman.
DX Engineering supports the build of the Asymmetrical Hatted Vertical Dipole (AHVD) antenna with standard and two custom parts.
We test a popular VHF/UHF dual band antenna at various angles to reveal antenna tilt on a vehicle matters only in certain circumstances.
A writer details how his ham father dissed his family by losing himself in technology. The story serves as a canary in the coal mine for “social media” then and now.
Near Vertical Incident Skywave (NVIS) propagation works wonders when the bands cooperate, but can slam the door shut at any moment.