Parabolic dish focal ratios & spillover angles
Admin
From Alex Pettit 2-3/12/2025: Its related to the Feed Beam Pattern and the Shape ( f/D Depth ) of the dish. “All” f/D 0.35 dishes perform similarly regardless of diameter…
Radio Astronomy
Applying the Nyquist theorem to radio astronomy
Great question — this is a very common confusion when first applying the Nyquist theorem to radio astronomy. You do not need a 2.8 GHz sample rate to observe the…
Nyquist theorem explanation
Here is the Nyquist explanation rewritten using pure ASCII diagrams (no Unicode). Nyquist Theorem (ASCII Version) The Nyquist theorem says: This minimum rate is the Nyquist rate. 1. Sine wave…
I have installed usbrelay softwate on Ubuntu for my 4 relay control board (which works on Windows). Running the command usbrelay detects device but can’t open it.
I have installed usbrelay softwate on Ubuntu for my 4 relay control board (which works on Windows). Running the command usbrelay detects device but can’t open it. If usbrelay sees…
Batch file used at LRO to process data Nov 2025
REM Identify data folder structure. REM The folder structure should be LRO folder with sub-folder called data. Save .txt data files in data and any .ezb and .npz data files…
British Astronomical Association Hydrogen Line Sub-group meeting 1/12/2025
https://files.ad.thornett.net/astronet/BAA_H-Line_Meeting_011225.mp4
Is it beneficial to have full wavelength sized antennas rather than half wavelength?
In most practical radio-astronomy and communication setups, a full-wavelength antenna is not inherently “better” than a half-wavelength one—they simply behave differently, and the choice depends on what pattern, impedance, and…
Comparing RTL-SDR v3 and v4 software defined radios
Here’s what’s inside — i.e. the chips used: In short: R820T2 tuner + RTL2832U demodulator/ADC. Since you’re already familiar with SDR and radio-astronomy, here’s a summary of the key components…
Dave Bracey’s Hydrogen Line 3D modelling of Milky Way arms
From Dave’s brilliant data set suppled 27/11/2025 – (c) Dave Bracey 2025 – all rights reserved. Taken using Dave’s 150cm homemade backyard radio telescope in Bromyard, England, UK, 2025.
When copper-wire properties start to matter in RF circuits
✅ When copper-wire properties start to matter. 1. Inductance becomes noticeable around ~10 kHz and up A typical straight copper wire has about: Inductive reactance: Example for L = 1…