Patent ID: 6373445
Filing Date: 2002-04-16
Classification: H01Q

Abstract:
A converter for an antenna to facilitate receiving signals from two satellites, the converter being provided with a receiving antenna capable of receiving:a right-hand circularly polarized radio wave within a first frequency band to be transmitted from a first artificial satellite; a right-hand circularly polarized radio wave within a second frequency band to be transmitted from a second artificial satellite, with frequencies of the second frequency band being higher than frequencies of the first frequency band; and a left-hand circularly polarized radio wave within the second frequency band to be transmitted from the second artificial satellite, the first and second artificial satellites being located so as to be received by the receiving antenna when the receiving antenna is aimed is a single receiving direction, and the converter being capable of converting received signals, from each of the received radio waves, into a received signal within a predetermined transmission frequency band having a frequency lower than the frequencies of the respective radio wave and being able to be simultaneously transmitted, together with received signals resulting from other radio waves, via a single transmission line; the converter comprising: a right-hand frequency changing portion, including a first oscillator for generating first oscillating signals, for changing frequencies of the received signals of the right-hand circularly polarized radio waves within the first and second frequency bands to convert the received right-hand circularly polarized radio waves, via use of the first oscillating signals, into received signals within the respectively predetermined transmission frequency bands; a left-hand frequency changing portion, including a second oscillator for generating second oscillating signal having an oscillation frequency lower than the first oscillating signals, for changing a frequency of the received signal of the left-hand circularly polarized radio wave within the second frequency band to convert the received left-hand circularly polarized radio wave, via use of the second oscillating signal, into a received signal within a transmission frequency band with frequencies higher than the frequencies of the received signals outputted from the right-hand frequency changing portion; a first filtering portion, provided along an output path for the received signals from the right-hand frequency changing portion, for passing the received signals from the right-hand frequency changing portion and for eliminating at least signal components within a frequency band similar to the received signal outputted from the left-hand frequency changing portion; a second filtering portion, provided along an output path for the received signal from the left-hand frequency changing portion, for passing of the received signal from the left-hand frequency changing portion and for eliminating at least signal components within frequency bands similar the received signals outputted from the right-hand frequency changing portion; and a received signals output portion for mixing the received signals from the right-hand frequency changing portion, passed through the first filtering portion, and the received signal from the left-hand frequency changing portion, passed through the second filtering portion, to thereby output the received signals at a common output-terminal.