How to service the 13-element Alex Pettit Hydrogen Line Yagi Antenna
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This antenna is used on LRO-H3 at LRO. From Alex Pettit: The spacers and plates are aluminum. The threaded rod they sit on is steel. Measure the DC resistance from…
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Scaling of flared section of hydrogen horn antenna
On Monday, 26 January 2026 at 08:32:18 GMT, andrew.thornett via Society of Amateur Radio Astronomers <sara-list@googlegroups.com> wrote: I notice that the SETI Horn of Plenty is a smaller version of…
How do switch blocks and selector blocks in GNU Radio work?
These two get mixed up all the time in GNU Radio because they sound similar but solve slightly different problems. I’ll explain them intuitively first, then a bit more technically,…
Pyramidal Horn Antenna Gain Calculator
Link below to URL of webpage with such a calculator: https://www.everythingrf.com/rf-calculators/pyramidal-horn-antenna-gain-calculator
What thickness of monopole probe in cantenna matches 50 ohm impedance of hydrogen line radio telescope?
There isn’t a single magic thickness that by itself gives 50 Ω — but in practice, for standard rectangular waveguide probe feeds, there is a very reliable working range that…
How does thickness of monopole probe in a waveguide affect impedance?
Short answer: a thicker monopole probe looks electrically “fatter,” which lowers its impedance and broadens the match. Longer, more intuitive version 👇 What’s going on physically A monopole probe in…
How to calculate F/D ratio of radio dish?
F/D is purely geometric. Once you know any two of diameter, focal length, or depth, you can calculate it. Definitions: D = dish diameterf = focal length (vertex to focus)d…
How do I find F and D if I don’t know them? (Focal length and diameter of a radio dish)
Short, honest answer first: you can’t get absolute F or D from the dish shape alone without at least one real measurement. A parabola has no inherent scale. But —…
What is design working temperature of Nooelec NESDR Smartee software defined radio?
The (Nooelec NESDR Smartee) USB SDR dongle does not have a publicly listed official “design or operating temperature range” in its published specifications from Nooelec. The manufacturer datasheets and product…
I am looking for a GNU Radio flowgraph on Github or elsewhere that shows me how to incorporate ability to choose between SDRs whilst running the program.
Here are some open-source GNU Radio flowgraphs / projects on GitHub that you can study or adapt when you want to choose between different SDR hardware sources (e.g., RTL-SDR, USRP,…