Once Maxwell's equations were published in the 1860's the entire field of antennas went from a new concept to merely engineering optimization for a specific application. BTW, I've found that a $50 NanoVNA makes antenna design and construction, including matching circuits and traps to be a breeze. Although I have an array of high-end commercial test equipment in my lab, having had a career in electronics for the last 5 decades, my experience is that a multimeter, a NanoVNA, and a TinySA are almost the only tools I need or use for ham radio, and they make the hobby much more fun while avoiding failures with my construction projects.
A good video. I did a little experimenting with EFHW and Fuchs antennas as well. I discovered that the ferrite core is not necessarily needed. An air-core transformer works just fine in this application (you better check the Q and the self-resonance frequencies, but they should be fine unless you do something stupid). Secondly, it looks like galvanic isolation between the primary and the secondary windings of the transformer improves the performance of the antenna - the RF power doesn't try to go to the coax, and putting an RFI choke on the coax doesn't affect any antenna properties.
at 18:3 we see the coax capacitor length should be 13cm .. 30cm depending on band, ok. But at 18:31 the coax stub in the plastic box is much shorter. How do you suggest to fit 30cm of RG-59 into the the suggested 80mmx80mmx50mm plastic box? 73
Love the qrp and homebrew approach from G and VK land!!
Brilliant video, heaps of info and good slides and graphics. I will save this video and check out the websites you list.👍
Once Maxwell's equations were published in the 1860's the entire field of antennas went from a new concept to merely engineering optimization for a specific application.
BTW, I've found that a $50 NanoVNA makes antenna design and construction, including matching circuits and traps to be a breeze. Although I have an array of high-end commercial test equipment in my lab, having had a career in electronics for the last 5 decades, my experience is that a multimeter, a NanoVNA, and a TinySA are almost the only tools I need or use for ham radio, and they make the hobby much more fun while avoiding failures with my construction projects.
@18:00 is the length of coax >10cm, but in the box @19:00 it is maybe 4cm. Why this difference?
please address specific questions to the presenter, they may not see them here.
A good video. I did a little experimenting with EFHW and Fuchs antennas as well. I discovered that the ferrite core is not necessarily needed. An air-core transformer works just fine in this application (you better check the Q and the self-resonance frequencies, but they should be fine unless you do something stupid). Secondly, it looks like galvanic isolation between the primary and the secondary windings of the transformer improves the performance of the antenna - the RF power doesn't try to go to the coax, and putting an RFI choke on the coax doesn't affect any antenna properties.
at 18:3 we see the coax capacitor length should be 13cm .. 30cm depending on band, ok. But at 18:31 the coax stub in the plastic box is much shorter. How do you suggest to fit 30cm of RG-59 into the the suggested 80mmx80mmx50mm plastic box? 73
please address specific questions to the presenter, they may not see them here.