Radio Propagation, Part 2
35 entries in the Radio Propagation, Part 2 compendium.
Long delayed echoRadio echoes returning seconds after transmission, with origins still debated.Maximum usable frequencyHighest frequency for skywave communication 50% of days in a month.Meteor burst communicationsBrief radio links via meteor trails, used for decades.Mie scatteringScattering of light by particles comparable to the wavelength.Multipath propagationMultipath causes signals to arrive via multiple paths, creating interference.MW DXHobby of receiving distant AM radio stations via skywave propagation.Non-line-of-sight propagationNLOS propagation occurs when visual line of sight is obstructed.North Atlantic Radio SystemCold War troposcatter chain linking Arctic radars to NORAD.Path lossPath loss is the reduction in signal strength as it travels from transmitter to receiver.Polar mesospheric summer echoesStrong radar echoes from 80–90 km in polar summer mesospheres.Radar angelsRadar angels are Bragg-scattering echoes from periodic structures like bird flocks.Karl RawerGerman specialist in radio wave propagation and the ionosphere.Rayleigh–Gans approximationApproximate solution for light scattering by optically soft particles.SidelobesUnwanted lobes in an antenna's radiation pattern, distinct from the main lobe.Signal-to-interference ratioQuotient of carrier power to co-channel interference power.Skip zoneA silent zone between ground-wave and sky-wave reception.SkywaveSkywave enables long-distance radio communication by reflecting signals off the ionosphere.Space weatherSpace weather studies solar wind effects on Earth's magnetosphere and ionosphere.SPLAT!GNU GPL-licensed tool for Longley-Rice path loss and coverage prediction.Sporadic E propagationUnpredictable VHF propagation via ionized patches in the lower E region.Sudden ionospheric disturbanceA sudden ionospheric disturbance disrupts radio communications via enhanced D-region absorption.Surface waveElectromagnetic or mechanical wave guided along an interface between two media.Tropospheric scatterMicrowave communication beyond the horizon using tropospheric scattering.TV and FM DXThe hobby of receiving distant TV and FM signals via unusual propagation.Voyager 1First spacecraft to enter interstellar space, launched in 1977.White Alice Communications SystemCold War tropospheric scatter network linking remote Alaskan defense sites.X bandA microwave band used for radar, space communications, and terrestrial broadband.Antenna (radio)Interface between radio waves and electric currents.Scimitar antennaA curved-plate VHF antenna used on spacecraft and aircraft.Antenna equivalent radiusEnables circular-cross-section analysis for non-circular antenna conductors.Antenna farmA dedicated area for multiple telecommunications transmitting or receiving antennas.Antenna measurementTesting antennas to characterize gain, pattern, impedance, and efficiency.Array gainArray gain measures SNR improvement from coherent signal addition across elements.Baseband processorA chip managing all antenna-based radio functions in a device.Beam diameterBeam diameter defines the spatial extent of an electromagnetic beam.
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