![NVIS: Near Vertical Incidence Skywave [ PodCast ]](https://qrznow.com/wp-content/uploads/2017/11/24180150.jpg)
Sometimes the best direction to send your signal is straight up!
Near vertical incidence skywave, or NVIS, is a skywave radio-wave propagation path that provides usable signals in the range between groundwave and conventional skywave distances—usually 30–400 miles (50–650 km). It is used for military and paramilitary communications, broadcasting,[1] especially in the tropics, and by radio amateurs. The radio waves travel near-vertically upwards into the ionosphere, where they are refracted back down and can be received within a circular region up to 650 km from the transmitter.[2] If the frequency is too high (that is, above the critical frequency of the ionospheric F layer), refraction fails to occur and if it is too low, absorption in the ionospheric D layer may reduce the signal strength.
There is no fundamental difference between NVIS and conventional skywave propagation; the practical distinction arises solely from different desirable radiation patterns of the antennas (near vertical for NVIS, near horizontal for conventional long-range skywave propagation).
Antenna
The Yagi-Uda Antenna
A Yagi-Uda antenna, commonly known simply as a Yagi antenna, is a directional antenna consisting of multiple parallel dipole elements in a line,[1] us... Read more
Three-band portable dipole antenna system
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25 Element Log Yagi 20-17-15-12-10m
OBLY25-5 25 Element Log Yagi 20-17-15-12-10m Bands 20 / 17 / 15 / 12 / 10 Gain (dBd) * 7,4 / 7,4 / 7,4 / 7,4 / 7,4 Gain (dBi) ** 14,7 /... Read more
Mechanical Issues with EFHW Antenna
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Review
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“I’m reviewing the new MFJ-2289 Big Ear Portable rotatable dipole antenna this week. I’ve switched things up just a bit and I’... Read more
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Digital Modes
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“Hi all, Many of us have made many QSOs using the new 77-bit messages on 7.078 and 14.078 MHz. Overall the results have been good — but no... Read more
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See More about New FT4 Here “At about 20 minutes into the presentation, Joe describes FT4 as being asynchronous, meaning that you can start tran... Read more
HF Signal Propagation PSK Reporter , PSK/JT65/FT-8/CW/JT9
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WinLink Radio Email with Yaesu FT-891
“Hello operators A few operators have left comments with concerns about the reported USB clicking on the Yaesu ft-891. Apparently one or more op... Read more
LoTW Now Accepting FT4 Contact
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Equipment
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Built by popular demand, the DX Engineering Ladder Line Surge Protector is ready to be placed in line with your balanced feedline antenna system! For... Read more
WS1098 Digital Scanner
The Whistler WS1098 desktop/mobile EZ Scan digital scanner with digital trunking technology features a new full keyboard, location-based auto programm... Read more
ALPIN 200 – LINEAR AMPLIFIER HF 2KW
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Soundcards and the SignaLink USB
Soundcards and the SignaLink USB Read more
![“Life Above 50 MHz” [ ARRL PODCAST ]](https://qrznow.com/wp-content/uploads/2019/01/vhf-136-174m-ham-radio-4elements-outdoor-yagi-antenna-vhf-radio-repeater-base-yagi-antenna-265x168.jpg)
