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Results tagged with propagation
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user 8717
Questions about RF propagation including measurements, beacons, modes (ionospheric, tropospheric, ground wave), etc.
0
votes
When will propagation on HF improve?
The short answer is nobody knows. Many of us want to know the same thing! :-)
I asked a similar question here. One of these days I'll update it with some information I found, which seems to indicate …
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5
votes
Is free space path loss dependent on frequency?
I'd like to offer a parallel and simplified explanation to W8II's correct answer above, for the mathematically-challenged VHF+ enthusiasts among us. :-)
As was mentioned in recent threads here, effec …
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2
votes
Can a Loop Antenna send and receive 10,000 miles away
The short answer is rarely, if at all on SSB.
STLs are notoriously lossy, since their radiation resistance is in the milliohm range. The best ones are made from large copper tubing, vacuum variable c …
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2
votes
Can I talk 2 Meter VHF across the United States
IIRC, even with two different kinds of exceptional propagation enhancements taking place simultaneously, and the fact that some of the farthest stations that he worked was because some of the signals were …
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3
votes
Where year 2016 falls in the sun spot cycle for HF propagation?
According to this chart, 2016 was not the solar minimum. We appear to be at or very near the minimum right now. However, we won't know for sure until some more time passes.
Yesterday on spaceweather.c …
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1
vote
How does VHF/UHF propagate beyond the expected (radio) horizon?
Historically, this is the best time of year (Late September through early December) in the northern hemisphere to enjoy VHF and UHF propagation enhancements ("band openings") caused by sharp air temperature …
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2
votes
Where does the year 2019 fall in the sunspot cycle for HF propagation?
TL;DR: As of March 2019, we have not yet reached the minimum of the current solar cycle. But we are close.
From Spaceweather.com:
Above: An historical record of the Thermosphere Climate Index. Mlyn …
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-1
votes
Practical limits to maintaining coherence in an HF channel
As Neils mentions, I don't see any better technique other than incorporating checksum exchange. This would be true regardless of the modulation technique.
For example, both stations could be half-dup …
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7
votes
Accepted
Looking for a book that contained a circuit for receiving (literally) underground amateur ra...
Yes, this most certainly was a thing, and people actually did it.
This type of communication has been done at ELF frequencies in the 3-30 kHz range. Their linear amplifiers were ordinary Hi-Fi audio …
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3
votes
How is it possible for an HF signal to go around the world when part of it must be in sunlight?
There is also gray-line propagation, where signals can travel around the world at the circular dusk/dawn annulus. In that region, it is neither totally dark nor totally light. …
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1
vote
Loop antenna layout and radiation?
To add to Brian's fine answer, I'd like to share some two-dimensional plots to complement his answer and 3D patterns.
To me, 2D plots are also necessary, because they show the actual takeoff angle vs …
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