Method and apparatus for mitigating interference from terrestrial broadcasts sharing the same channel with satellite broadcasts using an antenna with posterior sidelobes
An apparatus for simultaneously receiving a first signal from a non-terrestrial source and a second signal from a terrestrial source on the same or overlapping channels using a receive antenna with posteriorly-directed sidelobes is disclosed. The apparatus comprises at least one terrestrial transmitter transmitting information on at least one frequency simultaneously usable by at least one satellite transmitting to a satellite receive antenna having a sensitivity characterizable by a primary sensitive axis directed substantially at satellite. The terrestrial transmitter includes a azimuthal gain characteristic directed substantially away from the Earth's Equator. In an alternative embodiment, the terrestrial transmitter is disposed at a location defining a vector angularly displaced from the primary sensitive axis by an angle of less than 90 degrees. A method of transmitting information is also disclosed. In this method the information is transmitted on at least one frequency simultaneously usable by at least one satellite transmitting to a satellite receive antenna having a sensitivity characterizable by a primary sensitive axis directed substantially at the satellite and a posterior secondary sensitive axis. The method is performed by transmitting the information from a terrestrially-based transmitter to a terrestrial receive antenna in a direction substantially away from the Equator.
1. An apparatus capable of substantially simultaneous and non-interfering reception of a first signal transmitted on a channel from a non-terrestrial source and a second signal transmitted on the channel from a terrestrial source, comprising:
a first antenna, having a primary sensitive axis directed substantially at the non-terrestrial source and at least one secondary sensitive axis directed away from the primary sensitive axis by a first angle greater than 90 degrees; and
a second antenna having a sensitive axis directed away from the primary sensitive axis by a second angle less than 90 degrees;
wherein the second angle comprises a second angle azimuth component and a second angle elevation angle component, and wherein the second angle azimuth component is between approximately −90 and 90 degrees and the second angle elevation component is between approximately 10 and 90−δ degrees, wherein δ describes and angle from due South to a vector from the satellite receive antenna to the satellite.
2. The apparatus of claim 1 , wherein second angle is between approximately 10 degrees and 90 degrees.
3. The apparatus of claim 1 , wherein the second angle is approximately 10 degrees.
4. The apparatus of claim 1 , wherein the first angle is between approximately 96 and 132 degrees.
5. The apparatus of claim 1 , wherein the second antenna is disposed proximate the first antenna.
6. The apparatus of claim 1 , wherein the non-terrestrial source is a satellite.
7. The apparatus of claim 6 , wherein the satellite is disposed in a substantially geosynchronous orbit.
8. The apparatus of claim 6 , wherein the satellite is disposed in a substantially geostationary orbit.