Table of length of central supports for cantenna for dishes of different focal ratios
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For a dish: F = (F/D) x D where: F = focal length (support length) F/D = focal ratio D = dish diameter Example for a 1.0 m dish: +———–+—————-+…
Is a black hole an isoptropic radiator?
Yes—if you mean isotropic radiator, then an ideal, non-rotating black hole is about as close as nature gets to one. An isotropic radiator emits the same power in every direction.…
What is the benefit, if any, of using expensive professional WR650 waveguide over homemade version?
For 1420 MHz work, the advantage of a professionally manufactured WR-650 waveguide is usually much smaller than many people expect. Electrical performance A commercial WR-650 section will have: At 1420…
Scientist who died when two pieces plutonium accidently went together at Los Alamos
You are probably thinking of Louis Slotin. On 21 May 1946 at Los Alamos Laboratory, Slotin was demonstrating a criticality experiment using a plutonium core later nicknamed the “Demon Core.”…
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Yes, 93,000 counts per minute (CPM) is a fairly strong reading for a Geiger test source, although how “large” it is depends on the detector and the source geometry. For…
Small, flat, rooftop satellite antennas could replace big, bulky, costly dishes
I asked ChatGPT to explain following to me: From https://newatlas.com/telecommunications/flat-rooftop-satellite-antennas/ “Ground Control to Major Tom,” the evergreen lyrics to David Bowie’s 70s hit, Space Oddity. What’s odd is that, despite…
Free dictation software on different platforms
Yes. There are several free options that will transcribe your speech into text as you dictate: Smartphones Windows PCs Linux For long interviews or lectures My recommendation Since you use…
What does 0.73 dB above background equate to in dBi for hydrogen line horn? I have a typical SETI of Plenty, 4 feet long and 3 feet wide, at 1420 MHz. Read the caveat that comes with this post.
Hydrogen-Line Detection vs Antenna Gain A measurement of 0.73 dB above background does not directly convert to dBi because they describe different things: So, whilst an attempt is made below…
Calculating gain achieved with LRO SETI Horn of Plenty using RTL-SDR V4 software-defined receiver 29/5/2026
Jason has calculated gain based on my plot below: I’m getting about 0.73 dB above background for that trace so pretty consistent with your previous results. Looks good! Jason Burnfield
Table comparing dB and dbi gain of SETI Horn of Plenty compared to 1m dish, 1.5m dish, 2m dish, 3m dish, 17 element patch Yagi, 86cm Ptarmigan Triffid 4 x 4 dipole array.
At the 1420.405 MHz hydrogen line, the SETI Horn of Plenty is generally quoted at about +20 dBi gain (roughly +18 dBd). For comparison: Antenna Approx Gain (dBi) Approx Gain…