What is a Pin Diode?
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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…
Radio observation in hydrogen line (1420MHz)
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…
What are professional radio astronomy dishes made of?
Professional radio astronomy dishes are engineered for electrical reflectivity, structural rigidity, thermal stability, and low weight. The exact construction depends on frequency range (long-wavelength vs millimetre work), but most large…
Rules of thumb in constructing hydrogen line feeds for amateur radio telescopes
The “rules of thumb”: c/o Ed Harfmann: Foil coating waveguide (if making waveguide with aluminium foil) wrinkled – Is it more than 1/20th of a wavelength? 21 cm/20 = 1.05…
How to test Nooelec SAWBird H1 LNA using a NanoVNA
Following information is from Alex Pettit:
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…
What brass tube will snugly fit inside or outside 1/8 inch diameter brass tubing, for making a tuneable cantenna monopole probe?
Here are the standard brass tube sizes that will fit snugly either inside or outside 1/8-inch brass tubing: 📏 Basic Dimensions of 1/8″ Brass Tube So you want tubing whose…