What is a Kumar choke for radio frequencies?
Admin
A Kumar choke (often called the VE4MA or Kumar feed/choke) is a choke-ring / cavity around a horn/feed that suppresses unwanted surface and coaxial currents and “traps” or reflects energy…
Radio Astronomy
LRO-H2 Radio Telescope (150cm Solar Cooker Dish)
Radio observation in hydrogen line (1420MHz)
Waveguides
In LRO-H2, I use a cantenna as my waveguide, and aim this at the dish, rather than out into space. Does the presence of the dish change the ideal dimensions for the cantenna and position and length of the monopole inside it?
Short answer: No—the dish doesn’t change the waveguide dimensions of the cantenna.The can’s internal diameter and the probe/back-short geometry are set by your operating frequency and waveguide mode, not by…
LRO-H2 Radio Telescope (150cm Solar Cooker Dish)
SDRplay RSPduo Software-Defined Radio (SDR)
Waveguides
Data collection video from LRO-H2 (150cm Dish & cantenna waveguide at 1420 MHz) with beta SDRplay RSPduo ezCol 01/11/2025-02/11/2025
Link below downloads video MP4 file:
Results drift scan LRO-H2 two orthogonal monopoles for SARA RTOP 2/11/2025
https://www.astronomy.me.uk/wp-content/uploads/2025/11/Results-drift-scan-LRO-H2-two-orthogonal-monopoles-for-SARA-RTOP-021125.pptx
LRO-H2 Radio Telescope (150cm Solar Cooker Dish)
Radio observation in hydrogen line (1420MHz)
SDRplay RSPduo Software-Defined Radio (SDR)
Processing first light data from LRO-H2 using beta ezCol SDRplay Python script 2/11/2025
https://www.astronomy.me.uk/wp-content/uploads/2025/11/Beta-ezCol-SDRplay-Data-Analysis-First-Light-for-SARA-RTOP-021125.pptx https://www.astronomy.me.uk/wp-content/uploads/2025/11/LRO-H2_RSPduo_251102_00.zip https://www.astronomy.me.uk/wp-content/uploads/2025/11/Ted-Clines-new-ezCol-and-SDRplay-drivers-251101a.zip
References on OH maser spectra and variability from SARA RTOP meeting 2/11/2025
V669 Cas is quite variable it seems… https://hsweb.hs.uni-hamburg.de/projects/nrt_monitoring/stockert.html eduard 19:32This is also a very good resource for OH maser spectra and variability: https://hsweb.hs.uni-hamburg.de/projects/nrt_monitoring/index.html Wolfgang Herrmann 19:33And this one https://hsweb.hs.uni-hamburg.de/projects/nrt_monitoring/stockert.html
How are coaxial relays controlled from the computer to allow software like SDR Sharp to collect calibration data vs signal data?
Copy of email sent to me by Ted Cline October 2025: How are coaxial relays controlled from the computer to allow software like SDR Sharp to collect calibration data vs…
LRO-H2 Radio Telescope (150cm Solar Cooker Dish)
Radio observation in hydrogen line (1420MHz)
SDRplay RSPduo Software-Defined Radio (SDR)
Processing first light data from LRO-H2 using beta ezCol SDRplay Python script 1-2/11/2025
Shows some hydrogen – need to complete full 24 hours and re-analyse. Note altitude and azimuth may be incorrect in these plots.
Is there any advantage to using RF filters when detecting Jupiter radio emissions?
Yes — RF filters can significantly improve your ability to detect Jupiter’s radio emissions, depending on your setup and local RF environment. Here’s a breakdown of when and why they…
How physically big can a cavity RF filter be made? For example, is there an advantage to making a 50cm long cavity filter for 1420 MHz?
Short answer: you can make a cavity “as big as you like,” but past a sensible size you don’t gain performance—and you often make things worse (more spurious modes, weight,…