Calculating the length of 1.4GHz Hydrogen Monopole Probe to use inside a cantenna
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Posted by Alex Pettit on SARA Mailing List 18/1/2026: Typical calculation for a one quarter wavelength (1/4 WL) antenna is WL / 4 * 0.95 211 /4 * 0.95 =…
Radio observation in hydrogen line (1420MHz)
Incorrect length of boom for feed on Nooelec 1.4 GHz tuned mesh dish and feed
Following results of investigations by Alex Pettit were posted on SARA Mailing List 20/1/2026: The “Nooelec 1.4GHz” feed seems improperly designed : the Focal Point of a 1m f/D 0.35…
Wavelengths covered by Ptarmigan Triffid Dipole Array used at LRO
That helps a lot — Ptarmigan Triffid immediately explains the confusion 👍 You have not used the wrong antenna, only the wrong band name. Ptarmigan & Triffid (UK Army) The…
Radio observation in hydrogen line (1420MHz)
SETI Horn of Plenty (Hydrogen Line Pyramidal Horn Design Antenna)
Waveguides
Show field patterns at 1420 MHz, derive wave impedance vs frequency, explain why feed probes behave oddly near cutoff, and compare WR-650 vs WR-770 specifically for H-line work.
Excellent — I’ll go through all four, keeping it practical and tied to 1420.405 MHz H-line work with WR-650. 1. Field patterns in WR-650 at 1420 MHz For the dominant…
Radio observation in hydrogen line (1420MHz)
SETI Horn of Plenty (Hydrogen Line Pyramidal Horn Design Antenna)
Waveguides
Why do some websites describe WR-650 waveguides as being for frequencies higher than 1420 MHz? Give equations in ASCII format.
Short answer: because different people are talking about different operating regions of the same waveguide, and some descriptions quietly assume single-mode, low-loss, well-matched operation rather than mere propagation. Here’s the…
Confusion between WR-65 and WR-650 rectangular waveguides
Here’s the clarification you need: ✅ WR-650 is a real, standard rectangular waveguide ❌ WR-65 is not a standard rectangular waveguide designation How the naming works So the confusion boils…
What does the 650 in WR650 waveguide name stand for?
WR-650 is the ideal rectangular waveguide for hydrogen line work. WR stands for Waveguide, Rectangular, and the number refers to the internal broad-wall dimension in hundredths of an inch. Specifically:…
Can an effective hydrogen line cantenna be 3D-printed by painting conductive paint on plastic printing material with or without copper infusion?
Conductive paint on a plastic cantenna without copper infusion in the plastic printing material: Short answer: usually no — conductive paint on a plastic cantenna is very unlikely to give…