![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
SDR Receiver with a Slinky Antenna
For years now Hams and Shortwave Listeners have been building antennas out of that great American toy: The Slinky. In this video we string two out to... Read more
SteppIR BigIR Concept and Unboxing
Description SteppIR Verticals are the only true ¼ wave continuous coverage antennas available for the HF bands. The SteppIR technology has had a profo... Read more
NEW PRODUCT – CHA SPIDER ASB
The CHA SPIDER ASB is an octagon-shaped Antenna Spoke Base designed to allow mounting of four dipole antennas that use the standard 3/8” x 24 stud ant... Read more
KT36XA – M2 Antenna – TriBand 10/15/20m
The M2 KT36XA is the result of many hours spent on perfecting the original KLM KT-34XA through computer optimization confirmed by range and actual on-... Read more
Review
SAQ Alexanderson Alternator Transmission Set for Christmas Eve
Sweden’s Alexanderson alternator station SAQ has planned a Christmas Eve transmission on 17.2 kHz. The transmitter will be tuned up starting at around... Read more
WA9ZCO Wins the February QST Cover Plaque Award
The winning article for the February 2020 QST Cover Plaque award is “CW Combo Key” by Marc Alan Winzenried, WA9ZCO. The QST Cover Plaque Award —... Read more
Book Review: Radio Frequency Interference (RFI) Pocket Guide
“Radio Frequency Interference (RFI) Pocket Guide” by Kenneth Wyatt, WA6TTY and Michael Gruber, W1MG This small 88-page spiral bound (3” x 5”) pocket g... Read more
RigExpert AA-230 Antenna Analyzer Unboxing and Initial
The RigExpert AA-230 Zoom analyzer is designed for measuring SWR (standing wave ratio), return loss, cable loss, as well as other parameters of cable... Read more
Digital Modes
Third Public Test of FT8 DXpediton Mode Deemed a Success
The third public test of FT8 DXpedition Mode on May 5 is being called a success. The goal of the exercise was to simulate a rare DXpedition pileup on... Read more
New Digital Modes Changing Complexion of Bands and Perhaps of Ham Radio
The wave of software-based digital modes over the past several years has altered the atmosphere of the HF bands. Some suggest the popularity of modes... Read more
K1JT , JOE TAYLOR HINTS AT POSSIBLE NEW MODE!
In a post to the WSJT-X email group today, Joe Taylor K1JT hinted at some ongoing experimentation of a new digital mode with sub-modes. His post was a... Read more
Equipment
Vectronics HFT-1500 OLLER TUNER, HF, 1500W, BAR GRAPH, SWR/WATTMETER
Arc-Free Operation Two heavy duty 4.5 kV transmitting variable capacitors and a massive high current roller inductor gives you arc-free operation up t... Read more
Ailunce HS2 HF VHF UHF SDR Transceiver
Ailunce HS2 is an ultra-portable full-frequency full-mode SDR radio. The HAM-BOX mobile app we developed allows the mobile phone to easily control and... Read more
Small QRP-GO-BOX powered by Raspberry Pi4, KX2 and TH-D74
Small multifunctional, digital, very compact amateur radio station for the radio operation at home, on the way or in the emergency radio. For the digi... Read more
SunSDR2 PRO
The brand new SunSDR2 PRO transceiver is a modern SDR transceiver developed with contesting and DXing in mind. It covers all HF bands plus 50 M... Read more
AnyTone AT-5555N 10 Meter Radio – 30 Watts
AnyTone AT-5555N GENERAL SPECIFICATIONS Frequency Coverage: 28.000 to 29.699 Mhz Antenna Impedance: 50 ohm, unbalanced Frequency Control: Digital Phas... Read more
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