RF choke designs
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An RF choke is an inductor designed to present a high impedance to radio-frequency currents while allowing DC or low-frequency currents to pass. The best design depends on the frequency…
May 2026
HP10509A Circular Loop Antenna.
The HP 10509A Circular Loop Antenna is a specialized active magnetic-loop receiving antenna developed by Hewlett-Packard in the early 1960s. It was originally supplied with the HP 117A VLF Comparator…
What is a balanced feed line in radio astronomy?
A balanced feed line is a transmission line in which the two conductors carry equal currents in opposite directions, and neither conductor is connected to ground. The electromagnetic fields are…
Link for VLF meeting tonight
https://us06web.zoom.us/j/83880385896?pwd=RaJleLpl3wWahgD8q8JCFMbaybeg5N.1
Radio observation in hydrogen line (1420MHz)
SETI Horn of Plenty (Hydrogen Line Pyramidal Horn Design Antenna)
What size oil tin about right to make WR650 waveguide for hydrogen line detection using a SETI Horn of Plenty?
For a WR-650 waveguide at the 1420 MHz hydrogen line, the internal dimensions need to be about 165 mm × 82.5 mm (6.5″ × 3.25″). That means you’re looking for…
Radio observation in hydrogen line (1420MHz)
SETI Horn of Plenty (Hydrogen Line Pyramidal Horn Design Antenna)
Can pyramidal horn antennas be scaled by adding an extra bit on front?
Yes, a pyramidal horn antenna can generally be made larger by adding an additional flared section to the front, but there are some important caveats. A horn antenna works by…
I have a professionally made and sold 1420 MHz rectangular waveguide I purchased from ebay. The probe has a bulbous end which I understand widens the reception in some way. What is likely range of frequencies it can pick up?
If your 1420 MHz rectangular waveguide feed has a probe with a bulbous, paddle-shaped, or capacitive end, that feature is usually intended to broaden the impedance match rather than dramatically…
Radio observation in hydrogen line (1420MHz)
SETI Horn of Plenty (Hydrogen Line Pyramidal Horn Design Antenna)
Horn antenna lecture from McMaster University
https://www.ece.mcmaster.ca/faculty/nikolova/antenna_dload/current_lectures/L18_Horns.pdf
How many degrees wide is M31 Andromeda Galaxy, in order that I can set up a radio mapping exercise on the 20m Skynet Dish at Greenbank Observatory using SARA account?
A perk of SARA membership that we can use the 20m Skynet dish. The angular size of the Andromeda Galaxy (M31) depends on how faint an outer region you include:…