ATSEP C Exam Questions and Complete Solutions Graded A+.

  If the is known, it is simple to calculate the angle of incidence required for the wave to return to ground. - Answer: Virtual Height F1 - Answer: 90-150 mi Critical frequency of F1 layer - Answer: 5 MHz Highest frequency that will be returned down to earth - Answer: Critical frequency Shortest distance from a TX measured along the surface of the earth - Answer: Skip distance If TX height = RX height, what is the max distance between 2 towers for LOS communications - Answer: 8 Hr Maxwell's equation - Answer: "that a changing magnetic field will produce an electric field and that a changing electric field will produce a magnetic field" Contains only reactive energy since electric and magnetic fields are 90 deg out of time phase. Of importance only in the immediate vicinity of the antenna. - Answer: Induction field Consists of the lines of force which have become detached from the antenna and are moving out into space as an electromagnetic wave. Electric and magnetic fields are in time phase. - Answer: Radiation field Occurs when 2 waves that left 1 source and travelled by different path arrive at a point after being reflected from ground. - Answer: Interference Increases ground wave coverage - Answer: Antenna Gain 3-30GHz - Answer: SHF Spectrum for high rate digital links, satellite, radar and navigation - Answer: EHF Impedance of free space - Answer: 377 ohms A form of electromagnetic radiation - Answer: Radio waves Velocity of waves depends on the - Answer: Medium Study of radiation patterns is simplified if the radiating element is considered - Answer: Isotropic Used for long distance telegraphy navigation such as Omega - Answer: Low Frequency Energy leaves transmitting antenna in the form of . - Answer: Wavefronts Bending from high electron density to regions of lower electron density. - Answer: Refraction Determined by the position of the electric field with respect to the reflecting surface. - Answer: Polarization Plot of electric field intensity at a fixed distance, as a function or direction from the antenna or antenna array. - Answer: Radiation Pattern Plotted in terms of relative field intensity, the interest in primarily the shape of the pattern - Answer: Pattern Points on pattern where the relative field strength is zero - Answer: Nulls Portions on the pattern between adjacent nulls - Answer: Lobes Lobes of a pattern having the greatest intensity - Answer: Major Lobes Lobes of a pattern having smaller maximum values - Answer: Minor Lobes Points on the pattern of greatest intensity - Answer: Maximums Field intensity at these points have values greater than zero - Answer: Minimums Description of pattern generally includes the locations of maximums and nulls - Answer: Shape Beyond 30 MHz is used. - Answer: Space waves Used for long distance communication at 3-30 MHz - Answer: Sky wave propagation NOT a fundamental properties of electromagnetic radiation - Answer: Power MARC fault - Answer: White cross on a red background If electric current is at -30 deg, where is the electric voltage after half wavelength? - Answer: -150 deg Not displayed when radio is on Standby mode - Answer: The standby indicator (red) is lit A type of propagation that includes all of the components of radio wave except those affected by the ionosphere. - Answer: Ground waves A polarization that electric phasor is perpendicular to the reflecting plane. - Answer: Vertical