Method and apparatus for separately controlling sky wave and ground wave radiation from a medium wave antenna
OwnerOgden L. Prestholdtinventor
Life of this patent
Estimating the term…
Abstract
In one embodiment, a horizontal antenna is mounted electrically separated from but near the top of a vertical antenna. For a given wattage and frequency and for two stations separated a known distance apart, the proscribed angle of elevation for ionospheric reflection for each station can be computed. The current and phase of the signal applied to the horizontal antenna can be adjusted to cancel the electromagnetic field waves emitted from the vertical antenna in the selected azimuth and angle of elevation. The cancellation effects waves of a certain angular orientation at the proscribed angle of elevation for ionospheric reflection.
Claims9
An antenna system for controlling the sky wave generated by a station in one or more azimuth directions psi and zenith directions theta comprising:
- one or more vertical antenna configurations generating an electromagnetic field E, said field having a field component E.sub..theta.V determined with respect to the azimuth direction psi and the zenith direction theta;
- one or more horizontal antenna configurations generating another electromagnetic field, said another field having a further field component E.sub..theta.H determined with respect to the zenith direction theta and azimuth direction psi and having an additional field component E.sub..PSI.H oriented in the psi direction;
- and,
- means for adjusting the magnitude of E.sub..theta.H and the phase of E.sub..theta.H generated by said horizontal antenna configuration for one or more angles of elevation of the station's ionospheric reflection corresponding to said azimuth directions psi such that E.sub..theta.V is substantially cancelled out by E.sub..theta.H at said angles of elevation and azimuth.
An antenna system for controlling the sky wave generated by a first station transmitting radio frequency signals, said first station having a proscribed angle of elevation for ionospheric reflection in relation to another station which is a predetermined distance from said first station, the antenna system comprising:
- a vertical antenna means for generating an electromagnetic field E carrying said radio frequency signals, said field having a field component E.sub..theta.V determined with respect to a zenith direction theta;
- a horizontal antenna means for generating another electromagnetic field carrying said radio frequency signals, said another electromagnetic field having a further field component E.sub..theta.H determined with respect to said zenith direction theta;
- and
- means for setting the magnitude and phase of said further field component E.sub..theta.H generated by said horizontal antenna means such that at said proscribed angle of elevation for ionospheric reflection said further field component E.sub..theta.H substantially cancels out said field component E.sub..theta.V generated by said vertical antenna means.
A method of limiting the sky wave radiation from a medium wave antenna system of a first station which transmits radio frequency signals and which is assigned a proscribed angle of elevation for ionospheric reflection based upon the distance between said first station and another station, the method comprising the steps of:
- providing a vertical antenna configuration;
- providing a horizontal antenna configuration;
- generating from said vertical antenna configuration an electromagnetic field E carrying said radio frequency signals, said field having a field component E.sub..theta.V in zenith direction theta;
- generating from said horizontal antenna configuration another electromagnetic field carrying said radio frequency signals, said another electromagnetic field having a further field component E.sub..theta.H in said zenith direction theta;
- modifying the magnitude and phase of said further field component E.sub..theta.H such that at said proscribed angle of elevation for ionospheric reflection said further field component E.sub..theta.H substantially cancels out said field component E.sub..theta.V.
Dependencies are inferred from the claim text.