Mini-Circuits ZHL-1217HLN Coaxial Low Noise Amplifier 1200-1700MHz
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Radio observation in hydrogen line (1420MHz)
The current range of 1420 MHz Hydrogen Line Filters and Low Noise Amplifiers supplied by GPIO.
Dr Andrew ThornettLichfield Radio Observatory – www.astronomy.me.uk GPIO Labs produces a selection of filters and low-noise amplifiers designed specifically for observations of the neutral hydrogen spectral line at 1420 MHz.…
What is a Pin Diode?
Absolute workhorse of RF switching. WHAT IS A PIN DIODE? A PIN diode is a semiconductor diode with three layers: The middle layer is a thick, undoped (intrinsic) region. That…
What is a Dicke switch in radio astronomy?
WHAT IS A DICKE SWITCH? A Dicke switch is a rapid RF switch used in radio astronomy to reduce receiver gain drift. It switches quickly between: This technique was invented…
Skin depth of copper and aluminium, and its implications for building radio telescopes
The skin depth (δ) of RF in copper at 1420 MHz can be calculated using the formula: δ = √(2/(ωμσ)) Where: At f = 1420 MHz (the hydrogen line frequency):…
Building tuneable waveguide probe
Since you’re building a tuneable waveguide probe (I’m assuming 1420 MHz given your past adventures…), here’s a clean, mechanically stable way to do it without it turning into a wobbly…
Software for Hydrogen-Line Radio Astronomy (H-Line RA, 1420 MHz)
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
Signal attenuation (loss) for common coaxial cables at around 1.42 GHz (1420 MHz), relevant for builders of amateur Hydrogen Line radio telescopes.
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…
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…