Building a horn antenna tuned for the 21 cm (1420.405 MHz) hydrogen line is a popular and effective way to do amateur radio astronomy. A horn antenna is especially good…
I asked ChatGPT how to do this, and here is its suggestion:
WR-650 already covers 1.12–1.70 GHz, so 1.420 GHz sits comfortably in-band—you don’t need to resize the guide. What you do need is a simple, well-tuned coax-to-waveguide probe with a backshort…
That’s a neat question — it sounds a bit counter-intuitive at first! https://www.astronomy.me.uk/wp-content/uploads/2025/10/1000036614-161025.png Here’s why a corner reflector antenna doesn’t just bounce the hydrogen-line radio waves back out into space,…
Yes — the dimensions of a horn antenna really matter for hydrogen line (1420 MHz, λ ≈ 21 cm) observing. The horn’s shape sets its gain, beamwidth, and impedance match,…
The short answer is: most computer monitors do not directly emit significant power at 1420 MHz, but they can produce harmonics, local oscillator leakage, or broadband RF noise that can…
Good question, Andrew — short answer: yes, up to a point, a larger corner reflector will generally improve hydrogen line observing, but there are trade-offs. Here’s the breakdown: 1. Collecting…
Example at the 21 cm Hydrogen Line For your 12-ft (3.65 m) dish, assuming ideal design efficiency η0=0.7\eta_0 = 0.7η0=0.7: RMS Surface Error (σ)ﾠσ / λﾠEfficiency (η/η₀)ﾠNet η 1 mmﾠ0.005ﾠ0.999ﾠ0.70…
A stressed dish (or stressed-skin parabolic reflector) is a lightweight reflector design where the parabolic surface is formed by tension and stress in the materials, rather than machining a rigid…
The screenshot below shows data collection on ezCol from both LRO-H2 Monopole 1 and LRO-H2 Monopole 2 (2 orthogonal polarisations on same cantenna waveguide on same 150cm parabolic reflector used…
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