Here’s a comparison of Paradar X-400 Ultra‑low‑loss Coaxial Cable (often called X-400) versus standard LMR‑400 Coaxial Cable (Per Metre) (the well-known low-loss 50 Ω coax): 📡 Purpose & Positioning X-400…
https://www.astronomy.me.uk/wp-content/uploads/2026/02/Software-for-H-Line-RA-180226-DRAFT-090226@2200.pdf https://www.astronomy.me.uk/wp-content/uploads/2026/02/Software-for-H-Line-RA-180226-DRAFT-090226@2200.pptx
https://www.astronomy.me.uk/wp-content/uploads/2026/02/Calculating-pyramidal-horn-gain-different-apertures-080226.pdf
Loss is a length multiplier, so a 200 ft length would have twice the loss shown above and a 50 ft length would have half the loss. This multiplier factor…
Some parts and alternatives that might help mount a ~30 cm or ~40 cm aluminium ring for waveguides — including raw material you can machine or tube rings / mounting…
Great question — this is one of those radio-astronomy tricks that feels almost too simple until you see why it works. The key idea A 50 Ω resistor at a…
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…
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…
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…
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…
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