Converter for receiving satellite signal

Abstract: Converter for receiving satellite signals comprising a waveguide (1,7) for receiving circularly polarized wave, vertically polarized wave and horizontally polarized wave from a satellite, mode transducers (2;21,22) for converting the polarized waves in the waveguide into signals on microstrip lines, first and second amplifiers (2;23,24) amplifying the outputs of the mode transducers, a third amplifier (2;25) amplifying the output of the first amplifier and output of the second amplifier, and a frequency converter (3) converting the frequency of the output of the third amplifier into intermediate frequency, wherein the pass length (26) of the path for the vertically polarized wave component of the introduced circularly polarized wave, and the pass length of the path for the horizontally polarized wave component of the introduced circularly polarized wave are set so that the signal at the input end of the first amplifier and the signal at the input end of the second amplifier are in the same phase, the first amplifier and second amplifier (2;23,24) are operated when receiving radio waves of circularly polarized wave, only the first amplifier (23) is operated and the second amplifier (24) is not when receiving vertically polarized wave, and only the second amplifier (24) is operated and first amplifier (23) is not when receiving horizontally polarized wave.

Description: BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a converter for receiving radio waves of circularly polarized wave, and radio waves of vertical and horizontal linearly polarized waves from a satellite. DESCRIPTION OF THE RELATED ART Recently, in addition to the broadcastings by using broadcasting satellite, broadcast using communication satellites began, and the variety of radio waves is increasing. The polarized wave modes of radio waves sent from satellites include the circularly polarized wave sent from broadcasting satellite, and the linearly polarized wave sent from communication satellite, and the circularly polarized wave is further classified into right-handed polarized wave and left-handed polarized wave, while the linearly polarized wave is classified into vertically polarized wave and horizontally polarized wave. Therefore, the converter for receiving satellite signals is preferred to be capable of receiving radio waves in all these different polarized wave modes. Referring to an example of a converter capable of receiving radio waves in plural different polarized wave modes, there is known a converter for receiving satellite signals capable of receiving both vertically polarized wave and horizontally polarized wave comprising a first rod antenna set in the direction of vertically polarized wave in a cylindrical waveguide, a second rod antenna set in the direction of horizontally polarized wave, a first amplifier for amplifying the output of the first antenna, a second amplifier for amplifying the output of the second antenna, and a frequency converter for converting the frequency of the outputs of the first amplifier and second amplifier into an intermediate frequency. In this converter for receiving satellite signals, however, waves circularly polarized can not be received. In other example, a converter for receiving satellite signals comprises a dielectric plate for converting circularly polarized wave into linearly polarized wave, a ferrite polarizer for rotating the polarizing direction of linearly polarized wave, and a mode transducer for receiving linearly polarized wave, which are disposed in series in a cylindrical waveguide, being designed to amplify the output of the mode transducer, and then convert the frequency. In this converter for receiving satellite signals, the dielectric plate is long as much as a length of 1/4 of wavelength of circularly polarized wave, and the circularly polarized wave is converted into a linearly polarized wave by the plate, while the other vertically polarized wave and horizontally polarized wave are passed directly without being converted in the polarizing direction. The ferrite polarizer is installed in a later stage of the dielectric plate in the propagation direction of radio waves, and the linearly polarized wave converted by the dielectric plate, and the linearly polarized wave passing through the dielectric plate without being converted are entered, the individual linearly polarized waves are converted into linear polarized waves in specific polarizing directions. The linear polarized wave converted thus in the specific polarizing direction is received by a mode transducer, such as a rod antenna set in the same polarizing direction, and is amplified and converted in frequency, and put out. Therefore, radio waves of circularly polarized wave, vertically polarized wave, and horizontally polarized wave can be all received. In this converter, however, in every input polarization mode, the ferrite polarizer must vary the rotation angle to be applied to polarization, and hence the magnetic field generating circuit and other constitution are complicated, and the apparatus becomes expensive. Examples of such types of converters are disclosed in EP-A-0 470 786, English abstract of JP-A-04 172 701, EP-A-0 523 770 and EP-A-0 542 615. It is hence a primary object of the invention to solve the above problems and present a converter for receiving satellite signals capable of receiving radio waves in all polarization modes of circularly polarized wave, vertically polarized wave and horizontally polarized wave. SUMMARY OF THE INVENTION To achieve the above object, the invention presents a converter for receiving satellite signals comprising a waveguide for receiving circularly polarized wave, vertically polarized wave and horizontally polarized wave from a satellite, a mode transducer for receiving vertically polarized wave converting the vertically polarized wave in the waveguide into a signal on a microstrip line, a mode transducer for receiving horizontally polarized wave converting the horizontally polarized wave in the waveguide into a signal on a microstrip line, a first amplifier for receiving the output of the mode transducer for receiving vertically polarized wave, a second amplifier for receiving the output of the mode transducer for receiving horizontally polarized wave, a third amplifier for receiving the output of the first amplifier and output of the second amplifier, and a frequency converter for receiving the output of the third amplifier and converting and producing the frequency, wherein the pass length of the path for the vertically polarized wave component of the introduced circularly polarized wave input to reach the first amplifier through the mode transducer for receiving vertically polarized wave, and the pass length of the path for the horizontally polarized wave component of the introduced circularly polarized wave to reach the second amplifier through the mode transducer for receiving horizontally polarized wave are set so that the signal at the input end of the first amplifier and the signal at the input end of the second amplifier are in the same phase, the first amplifier and second amplifier are operated when receiving radio waves of circularly polarized wave, only the first amplifier is operated and the second amplifier is not when receiving radio waves of vertically polarized wave, and only the second amplifier is operated and first amplifier is not when receiving radio waves of horizontally polarized wave. In this constitution, the converter for receiving satellite signals of the invention operates as follows. The mode transducer for receiving vertically polarized wave converts the vertically polarized wave propagating through the waveguide into a signal on microstrip line, and the mode transducer for receiving horizontally polarized wave converts the horizontally polarized wave propagating through the waveguide into a signal on microstrip line. The first amplifier amplifies the output signal of mode transducer for receiving vertically polarized wave, and the second amplifier amplifies the output signal of the mode transducer for receiving horizontally polarized wave. The third amplifier amplifies the composite signal of the output signal of the first amplifier and output signal of the second amplifier, and delivers it to the frequency converting circuit. Depending on the setting condition of the pass length determined by the position of the mode transducer and the transmission line length from the mode transducer to the input end of the amplifier, when circularly polarized wave is entered, the phase of signal at the input end of the first amplifier and the phase of signal at the input end of the second amplifier come to be in the same phase, and the third amplifier amplifies the composite signal of the signal of the vertically polarized wave component and the signal of horizontally polarized signal component of circularly polarized wave in phase, and delivers it to the frequency converting circuit. That is, the radio wave of circularly polarized wave is received of its vertically polarized wave component and horizontally polarized wave component, and it is adjusted so that the phase difference as much as π/2 radian between vertically polarized wave and horizontally polarized wave may be zero by setting of pass length so as to be synthesized in the same phase at at the input end of the third amplifier. When receiving the radio wave of vertically polarized wave, the first amplifier is operated and the second amplifier is not, and hence only the output of the mode transducer for receiving vertically polarized wave is amplified by the third amplifier. When receiving the radio wave of horizontally polarized wave, the second amplifier is operated and the first amplifier is not, so that only the output of the mode transducer for receiving horizontally polarized wave is amplified by the third amplifier. When receiving radio wave of circularly polarized wave, the phase difference as much as π/2 radian between the vertically polarized wave component and horizontally polarized wave component can be adjusted, for example, by the difference in pass length between the path for the virtically polarized wave to reach the first amplifier and the path for horizontally polarized wave to reach the second amplifier, that is, only by the difference of the transmission line length of microstrip line, and it is also possible to adjust by using the phase difference in the waveguide by varying the position of picking up the component polarized wave of circularly polarized wave from the waveguide by the mode transducer for receiving vertically polarized wave and mode transducer for receiving horizontally polarized wave. It is also possible to adjust by combining them. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a partial sectional view showing composition of a converter for receiving satellite signals in a first embodiment of the invention. Fig. 2 is a plan view showing composition of low noise amplifying circuit unit comprising mode transducers and amplifiers for receiving radio waves in left-handed circularly polarized wave, horizontally polarized wave and vertically polarized wave in the first embodiment. Fig. 3 is a plan view showing composition of low noise amplifying circuit unit comprising mode transducers and amplifiers for receiving radio waves in right-handed circularly polarized wave, horizontally polarized wave and vertically polarized wave in the first embodiment. Fig. 4 is a partial sectional view showing comosition of a converter for receiving satellite signals for receiving radio waves in left-handed circularly polarized wave, horizontally polarized wave and vertically polarized wave in a second embodiment. Fig. 5 is a plan view showing composition of a low noise amplifying circuit unit comprising mode transducers and amplifiers for receiving radio waves in left-handed circularly polarized wave, horizontally polarized wave and vertically polarized wave in the second embodiment. Fig. 6 is a partial sectional view showing comosition of a converter for receiving satellite signals for receiving radio waves in right-handed circularly polarized wave, horizontally polarized wave and vertically polarized wave in the second embodiment. DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 is a partial sectional view showing composition of the first embodiment of the invention. In the diagram, numeral 1 denotes a primary radiator for efficiently collecting the radio waves reflected by a reflector (not shown), and 2 is a low noise amplifying circuit unit, which comprises a mode transducer for receiving vertically polarized wave, a mode transducer for receiving horizontally polarized wave, microstrip lines, and amplifiers composed on a dielectric substrate 6. Numeral 3 is a frequency converting circuit unit, 4 is an intermediate frequency amplifying circuit unit, 5 is a connector, and 7 is a cylindrical waveguide coupled to the primary radiator 1 for leading in circularly polarized wave, vertically polarized wave, and horizontally polarized wave. On one side of the dielectric substrate 6, strip conductors of mode transducers and microstrip lines are composed of conductive members such as Cu and Ag-Pd, while the opposite surface is covered with a base conductor for forming the strip lines. Fig. 2 is a plan view showing a structural example of the low noise amplifying circuit unit 2. In Fig. 2, numeral 21 is a mode transducer for receiving vertically polarized wave, and 22 is a mode transducer for receiving horizontally polarized wave, both being composed of strip conductors of microstrip lines, and the base conductors confronting the strip conductors are removed in a form of window, and a lead-in window 29 for polarized wave is formed. Numeral 23 is a low noise amplifying transistor (hereinafter called merely a transistor) which is an amplifier for amplifying the output signal of the mode transducer 21 for receiving vertically polarized wave, 24 is a second transistor for amplifying the output signal of the mode transducer 22 for receiving horizontally polarized wave, 25 is a third transistor which is an amplifier for amplifying the composite signal of the output signal of the first transistor 23 and output signal of the second transistor 24, 26 is a microstrip line for transmitting the output signal of the mode transducer 22 for receiving horizontally polarized wave to the second transistor 24, 27 is a microstrip line for feeding the output signal of the first transistor 23 into the third transistor 25, and 28 is a microstrip line for feeding the output signal of the second transistor 24 into the third transistor 25, in which the line length of the microstrip line 27 and the line length of the microstrip line 28 are set identical. In the composition shown in Fig. 2, in order to receive the left-handed circularly polarized wave, the pass length from the mode transducer 22 for receiving horizontally polarized wave to the second transistor 24 is set longer than the pass length from the mode transducer 21 for receiving vertically polarized wave to the first transistor 23 by the portion of the transmission line length of the microstrip line 26, and this pass length difference is defined to be 1/4 of wavelength at the frequency of the left-handed circularly polarized wave. This low noise amplifying circuit unit 2 is installed inside the waveguide 7 and vertically to the axis of the waveguide 7 so that the base conductor side of the dielectric substrate 6 is opposite to the radio wave incident side, that the lengthwise direction of the mode transducer 21 for receiving vertically polarized wave may be in the vertical polarizing direction in the waveguide 7, and that the lengthwise direction of the mode transducer 22 for receiving horizontally polarized wave may be in the horizontal polarizing direction in the waveguide 7. The reason of defining a specific difference in the pass length is clear from the following description. In this constitution, the converter for receiving satellite signals in the embodiment operates as follows. The left-handed circularly polarized wave enters from the primary radiator 1, propagates through the waveguide 7, and reaches the low noise circuit unit 2 shown in Fig. 2. The left-handed circularly polarized wave consists of vertically polarized wave component and horizontally polarized wave component identical in amplitude, and the phase of the horizontally polarized wave component is advanced from that of the vertically polarized wave component by π/2 radian. The vertically polarized wave component of the circularly polarized wave reaching the low noise circuit unit 2 enters the mode transducer 21 for receiving vertically polarized wave from the lead-in window 29 on the dielectric substrate 2, and is converted into a signal on the microstrip line, while the horizontally polarized wave component enters the mode transducer 22 for receiving horizontally polarized wave from the lead-in window 29 of the base conductor, and is converted into a signal on the microstrip line. Of these converted signals on the microstrip line, as mentioned above, the signal due to horizontally polarized wave component is advanced by π/2 from the signal due to vertically polarized wave component. Therefore, since the transmission line length from the mode transducer 22 for receiving horizontally polarized wave to the second transistor 24 is set longer than the transmission line length from the mode transducer 21 for receiving vertically polarized wave to the first transistor 23, by the length of 1/4 of wavelength at the frequency of left-handed circularly polarized wave, the signals are in phase at the input ends of the first transistor 23 and second transistor 24. Therefore, by summing up the output signal of the first transistor 23 and the output signal of the second transistor 24, it is possible to synthesize effectively in the same phase. As shown in Fig. 2, by synthesizing the amplification output of the first transistor 23 and the amplification output of the second transistor 24 by feeding into the third transistor 25 through the microstrip line 27 and microstrip line 28 of the same transmission line length, the left-handed circularly polarized wave is separated into the vertically polarized wave component and horizontally polarized wave component and received, and then synthesized in the same phase and received. This composite signal is amplified by the third transistor 25, and is converted in frequency to the intermediate frequency in the frequency conversion circuit 3, and is further amplified in the intermediate frequency amplifying circuit 4, and is delivered from the connector 5. In this operation, the radio wave of left-handed circularly polarized wave is received. Next is explained the operation of receiving radio waves of horizontally polarized wave and vertically polarized wave. The horizontally polarized wave and vertically polarized wave entering the primary radiator 1 propagate through the waveguide 7, and reach the mode transducer 21 for receiving vertically polarized wave and mode transducer 22 for receiving horizontally polarized wave on the dielectric substrate 6 of the low noise amplifying circuit unit 2. The vertically polarized wave is converted into a signal on the microstrip line by the mode transducer 21 for receiving vertically polarized wave, and the horizontally polarized wave is converted into a signal on the microstrip line by the mode transducer 22 for receiving horizontally polarized wave. When receiving only the vertically polarized wave, only the first transistor 23 for amplifying the signal of vertically polarized wave is operated, and the second transistor 24 for amplifying the signal of horizontally polarized wave is not operated, so that only the vertically polarized wave received by the mode transducer 21 for receiving vertically polarized wave is amplified by the third transistor 25 and is delivered to the frequency converter 3. When receiving only the horizontally polarized wave, only the second transistor 24 for amplifying the horizontally polarized wave is operated, and the first transistor 23 for amplifying the vertically polarized wave is not operated, so that only the horizontally polarized wave is amplified by the third transistor 25, and is delivered to the frequency converter 3. Thus, the radio waves of vertically polarized wave and horizontally polarized wave can be received. The above constitution relates to the composition for receiving left-handed circularly polarized wave, vertically polarized wave and horizontally polarized wave, and next is explained the operation in which the circularly polarized wave is a right-handed circularly polarized wave. Fig. 3 relates to a constitution comprising mode transducer for receiving vertically polarized wave, mode transducer for receiving horizontally polarized wave, and amplifiers in low noise amplifying circuit unit 2, for receiving right-handed circularly polarized wave, horizontally polarized wave, and vertically polarized wave. In Fig. 3, numeral 31 denotes a mode transducer for receiving vertically polarized wave composed of strip conductors in microstrip lines, and 32 is a mode transducer for receiving horizontally polarized wave composed of strip conductors in microstrip lines, and mutually confronting base conductors are removed in a window form, and a lead-in window 29 for polarized wave is formed. The other constituent elements are same as in the case of left-handed circularly polarized wave shown in Fig. 2. In the constitution for receiving right-handed circularly polarized wave, the pass length from the mode transducer 31 for receiving vertically polarized wave to the first transistor 23 is set longer than the pass length from the mode transducer 32 for receiving horizontally polarized wave to the second transistor 24 by the portion of the line length of the microstrip line 26, and this difference is defined to be 1/4 of wavelength at the frequency of the right-handed circularly polarized wave. The low noise amplifying circuit unit 2 having these elements is installed vertically to the axis of the waveguide 7, same as in the case of left-handed circularly polarized wave. The mode transducer 31 for receiving vertically polarized wave is set so that its lengthwise direction may be in the vertical polarizing direction in the waveguide 7, and the mode transducer 32 for receiving horizontally polarized wave is set so that its lengthwise direction may be in the horizontal polarizing direction in the waveguide 7. In this constitution, the operation is as follows. The right-handed circularly polarized wave entering the primary radiator 1 propagates in the waveguide 7, its vertically polarized wave component of the right-handed circularly polarized wave is converted into a signal on the microstrip line by the mode transducer 31 for receiving vertically polarized wave disposed vertically, and the horizontally polarized wave component of the right-handed circularly polarized wave is converted into a signal on the microstrip line by the mode transducer 32 for receiving horizontally polarized wave disposed horizontally. In the case of right-handed circularly polarized wave, the phase of its vertically polarized wave component is advanced from the phase of horizontally polarized wave component by π/2 radian. Hence, since the transmission pass line from the mode transducer 31 for receiving vertically polarized wave to the first transistor 23 is set longer than the transmission pass length from the mode transducer 32 for receiving horizontally polarized wave to the second transistor 24 by the portion of 1/4 of wavelength at the frequency of right-handed circularly polarized wave, the signals are in phase at the input ends of the first transistor 23 and second transistor 24. Therefore, by feeding the output signals into the third transistor 25 through the microstrip lines 27, 28, respectively, they can be synthesized effectively in the same phase. Incidentally, the operation when receiving vertically polarized wave or horizontally polarized wave is same as explained above, and detailed description is omitted herein. According to the embodiment, in this way, the mode transducer for receiving vertically polarized wave and the mode transducer for receiving horizontally polarized wave are installed on a vertical section of the waveguide, the output signal of the mode transducer for receiving vertically polarized wave is connected to the first transistor, and the output signal of the mode transducer for receiving horizontally polarized wave is connected to the second transistor, and the respective output signals are synthesized, and connected to the third transistor. In the composition for receiving the left-handed circularly polarized wave, vertically polarized wave and horizontally polarized wave, the transmission line length until the signal of the mode transducer for receiving horizontally polarized wave reaches the input end of the first transistor is set longer than the transmission line length until the signal of the mode transducer for receiving vertically polarized wave reaches the input end of the second transistor by the portion of 1/4 of wavelength at the frequency of the input left-handed circularly polarized wave, whereas in the composition for receiving the right-handed circularly polarized wave, vertically polarized wave and horizontally polarized wave, the transmission line length until the signal of the mode transducer for receiving vertically polarized wave reaches the input end of the second transistor is set longer than the transmission line length until the signal of the mode transducer for receiving horizontally polarized wave reaches the input end of the first transistor by the portion of 1/4 of wavelength at the frequency of the input right-handed circularly polarized wave. In this constitution, when receiving the radio wave of circularly polarized wave, by operating the first transistor and second transistor, the horizontally polarized wave component and vertically polarized wave component of circularly polarized wave are received, and they can be received by synthesizing in the same phase. When receiving radio wave of horizontally polarized wave, the first transistor is operated and the second transistor is not, or when receiving radio wave of vertically polarized wave, the second transistor is operated and the first transistor is not, so that the radio waves may be received. In the embodiment, the cylindrical waveguide is used, but the same effects are obtained by using other waveguide capable of introducing circularly polarized wave, vertically polarized wave, and horizontally polarized wave, for example, an elliptical waveguide. Fig. 4 relates to a second embodiment of the invention, showing a side sectional view of a composition of a converter for receiving satellite signals for receiving left-handed circularly polarized wave, and linearly polarized wave of horizontally polarized wave and vertically polarized wave. In Fig. 4, numeral 1 denotes a primary radiator for efficiently collecting the radio waves reflected by a reflector (not shown), and 2 is a low noise amplifying circuit unit, which comprises a mode transducer for converting the polarized wave in a waveguide into a signal on a microstrip line disposed on a dielectric substrate 6, 3 is a frequency converting circuit unit, 4 is an intermediate frequency amplifying circuit unit, 5 is a connector, 7 is a cylindrical waveguide coupled to the primary radiator 1, 47 is a mode transducer for receiving vertically polarized wave composed of copper, silver or other metal bar, having one end connected to a microstrip line on the dielectric substrate 6, and the other end disposed in the vertical polarizing direction so as to project into the waveguide, 48 is a mode transducer for receiving horizontally polarized wave disposed at a position confronting a slit 7A provided in the wall of the waveguide 7, and 49 is a metal plate for reflecting the vertically polarized wave in the waveguide. The mode transducer 48 for receiving horizontally polarized wave is set at a position remove by the portion of 1/4 wavelength at the frequency of left-handed circularly polarized wave, at a later stage of the mode transducer 47 for receiving vertically polarized wave. Fig. 5 is a plane view showing composition of low noise amplifying circuit unit comprising a mode transducer for horizontally polarized wave and transistors for amplifying mounted on a dielectric substrate 6. In Fig. 5, numeral 51 denotes a microstrip line for transmitting the output of the mode transducer 47 for receiving vertically polarized wave to a first transistor 53, and 48 is a mode transducer for receiving horizontally polarized wave composed of strip conductor of microstrip line, and the base conductor corresponding to it is removed in a window form to form a lead-in window 29 of polarized wave. Numeral 53 is s first transistor for amplifying the output signal of the mode transducer 47 for receiving vertically polarized wave, 54 is a second transistor for amplifying the output signal of the mode transducer 48 for receiving horizontally polarized wave, and 55 is a third transistor for amplifying the synthesized signal of the output signal of the first transistor 53 and the output signal of the second transistor 54. The transmission line length of the microstrip line 51 from the mode transducer 47 for receiving vertically polarized wave to the first transistor 53, and the transmission line length from the mode transducer 48 for receiving horizontally polarized wave to the second transistor 54 are set identically. The dielectric substrate 6 is placed horizontally, and it is so set that the lengthwise direction of the mode transducer 48 for receiving horizontally polarized wave may be in the horizontal polarizing direction in the waveguide 7. In this constitution, the embodiment operates as follows. The left-handed circularly polarized wave entering through the primary radiator 1 propagates in the waveguide 7. The vertically polarized wave component of the left-handed circularly polarized wave is converted into a signal on the microstrip line 51 by the mode transducer 47 for receiving vertically polarized wave. The vertically polarized wave is reflected by the metal plate 49 so as not to be propagated to the mode transducer 48 for receiving horizontally polarized wave. On the other hand, the horizontally polarized wave component of the left-handed circularly polarized wave propagates in the waveguide 7 without being shielded by the metal plate 49, and enters the mode transducer 48 for receiving horizontally polarized wave through the slit 7A in the waveguide and the lead-in window 29 of the base conductor in the strip line, and is converted into a signal on the microstrip line. As explained in the first embodiment, in the case of left-handed circularly polarized wave, the phase of the horizontally polarized wave component is advanced from the phase of vertically polarized wave component by π/2 radian. Hence, since the mode transducer 48 for receiving horizontally polarized wave is installed at a position 1/4 wavelength delayed, in a later stage of the mode transducer 47 for receiving vertically polarized wave in the propagation direction of radio wave, the phase of the signal at the input end of the first transistor and the phase of the signal at the input end of the second transistor 54 are the same. Therefore, by summing up these output signals through the microstrip line 52 and microstrip line 56 in the same propagation line length, they can be synthesized effective in the same phase. This synthesized signal is amplified by the third transistor 55, and fed into the frequency conversion circuit 3, so that the vertically polarized wave component and horizontally polarized wave component of the left-handed circularly polarized wave are individually received, synthesized, and then left-handed circularly polarized wave can be received. Referring then to the operation of receiving the radio waves of vertically polarized wave, same as in the first embodiment, by operating the first transistor 53 and not operating the second transistor 54, only the signal of the vertically polarized wave converted by the mode transducer 47 for receiving vertically polarized wave can be received, and by operating the second transistor 54 and not operating the first transistor 53, only the signal of the horizontally polarized wave converted by the mode transducer 48 for receiving horizontally polarized wave can be received. By this operation, the radio wave of left-handed circularly polarized wave, and the radio wave of vertically polarized wave or radio wave of horizontally polarized wave can be received. Fig. 6 is a side sectional view showing composition of converter for receiving satellite signals for receiving radio waves of right-handed circularly polarized wave, and radio waves of vertically polarized wave and horizontally polarized wave. In Fig. 6, numeral 1 is a primary radiator, 2 is a low noise amplifying circuit unit, 3 is a frequency converting circuit unit, 4 is an intermediate frequency amplifying circuit unit, 5 is a connector, 7 is a waveguide, 7B is a slit provided in the waveguide 7 for leading horizontally polarized wave into the waveguide 7, 69 is a reflector for reflecting horizontally polarized wave, 47 is a mode transducer for receiving vertically polarized wave, and 48 is a mode transducer for receiving horizontally polarized wave. Since the phase of vertically polarized wave component of right-handed circularly polarized wave is advanced from the phase of the horizontally polarized wave by π/2 radian, the phase difference of π/2 is corrected by installing the mode transducer 47 for receiving vertically polarized wave at a position 1/4 wavelength delayed at the frequency of the right-handed circularly polarized wave, in a later stage of the mode transducer 48 for receiving horizontally polarized wave. In this case, the composition of the low noise amplifying circuit unit 2, the receiving operation of right-handed circularly polarized wave, and receiving operation of radio waves of vertically polarized wave and horizontally polarized wave are evident from the description of the embodiment shown in Fig. 4 and Fig. 5, and detail explanation is omitted herein. Thus, according to the second embodiment of the invention, the mode transducer for receiving vertically polarized wave is composed of a metal bar, and disposed in the waveguide projecting in the vertical polarizing direction, the mode transducer for receiving horizontally polarized wave is composed of strip conductor of microstrip line, and disposed in the waveguide in the horizontal polarizing direction, confronting the slit in the wall of the waveguide, the signals converted by them are fed into first and second transistors for amplification, the signals are synthesized and fed into the third transistor, and the mode transducer for receiving vertically polarized wave and mode transducer for receiving horizontally polarized wave are disposed so as to pick up the component polarized wave from the position in the waveguide separated by 1/4 wavelength at the frequency of the circularly polarized wave, in order that the phase of the signal at the input end of the first transistor and the phase of the signal at the input end of the second transistor may be the same, thereby receiving radio waves of circularly polarized wave. By operating either the first transistor or the second transistor and not operating the other, either the radio wave of vertically polarized wave or the radio wave of horizontally polarized wave may be received. In the first embodiment, meanwhile, the phase difference of the signal due to vertical component of circularly polarized wave and the signal due to horizontally polarized wave component is adjusted by the transmission line length of the microstrip line, whereas in the second embodiment, it is adjusted by varying the pickup position of the signal of polarized wave component from the waveguide, and it is also possible, as evidently known, to adjust by combining these two means.

Claims: A converter for receiving satellite signals comprising a waveguide (7) for receiving radio waves of circularly polarized wave, vertically polarized wave and horizontally polarized wave from a satellite, a mode transducer (21) for receiving vertically polarized wave for converting the vertically polarized wave in the waveguide into a signal on a microstrip line, a mode transducer (22) for receiving horizontally polarized wave for converting the horizontally polarized wave in the waveguide into a signal on a microstrip line, a first amplifier (23) amplifying the output of the mode transducer (21) for receiving vertically polarized wave, a second amplifier (24) amplifying the output of the mode transducer (22) for receiving horizontally polarized wave, a third amplifier (25) amplifying the output of the first amplifier (23) and output of the second amplifier (24), and a frequency converter (3) converting the frequency of the output of the third amplifier (25) into intermediate frequency, characterized in that the pass length of the path for the vertically polarized wave component of the introduced circularly polarized wave input to reach the first amplifier (23) through the mode transducer (21) for receiving vertically polarized wave, and the pass length of the path for the horizontally polarized wave component of the introduced circularly polarized wave input to reach the second amplifier (24) through the mode transducer (22) for receiving horizontally polarized wave, are set so that the signal at the input end of the first amplifier (23) and the signal at the input of the second amplifier (24) are in the same phase, the first amplifier (23) and the second amplifier (24) are operated when receiving radio waves of circularly polarized wave, only the first amplifier (23) is operated and the second amplifier (24) is not when receiving radio waves of vertically polarized wave, and only the second amplifier (24) is operated and first amplifier (23) is not when receiving radio waves of horizontally polarized wave. A converter for receiving satellite signals of claim 1, wherein the mode transducer (21) for receiving vertically polarized wave and the mode transducer (22) for receiving horizontally polarized wave are composed of strip conductors of microstrip line, and disposed in the waveguide. A converter for receiving satellite signals of claim 1, wherein the mode transducer (21) for receiving vertically polarized wave is composed of a bar conductor disposed in the waveguide projecting in the vertical polarizing direction. A converter for receiving satellite signals of claim 1, wherein the mode transducer (22) for receiving horizontally polarized wave is fed the horizontally polarized wave through a slit provided in the waveguide wall. A converter for receiving satellite signals of claim 1, wherein the mode transducer (21) for receiving vertically polarized wave and the mode transducer (22) for receiving horizontally polarized wave are disposed on a same cross section in the waveguide. A converter for receiving satellite signals of claim 5, wherein the line length from the output end of the mode transducer (22) for receiving horizontally polarized wave to the input end of the second amplifier (24) is set longer than the line length from the output end of the mode transducer (21) for receiving vertically polarized wave to the input end of the first amplifier (23) by the portion of 1/4 wavelength at the frequency of the left-handed circularly polarized wave, thereby receiving the left-handed circularly polarized wave, vertically polarized wave and horizontally polarized wave. A converter for receiving satellite signals of claim 5, wherein the line length from the output end of the mode transducer (31) for receiving vertically polarized wave to the input end of the first amplifier (23) is set longer than the line length from the output end of the mode transducer (32) for receiving horizontally polarized wave to the input end of the second amplifier (24) by the portion of 1/4 wavelength at the frequency of the right-handed circularly polarized wave, thereby receiving the right-handed circularly polarized wave, vertically polarized wave and horizontally polarized wave. A converter for receiving satellite signals of claim 1, wherein the mode transducer (21) for receiving vertically polarized wave end the mode transducer (22) for receiving horizontally polarized wave are disposed in the front and rear positions in the radio wave propagating direction in the waveguide. A converter for receiving satellite signals of claim 1, wherein the mode transducer (48) for receiving horizontally polarized wave is disposed behind in the radio wave propagating direction of the waveguide of the mode transducer (47) for receiving vertically polarized wave, at a position remote by the portion of 1/4 of the wavelength, thereby receiving the left-handed circularly polarized wave, vertically and horizontally polarized waves. A converter for receiving satellite signals of claim 1, wherein the mode transducer (47) for receiving vertically polarized wave is disposed behind in the radio wave propagating direction of the waveguide of the mode transducer (48) for receiving horizontally polarized wave, at a position remote by the portion of 1/4 of the wavelength, thereby receiving the right-handed circularly polarized wave, vertically and horizontally polarized waves.

Inventors: KASHIMA YUKIRO, KINOSHITA AKIRA, KASHIMA, YUKIRO, KINOSHITA, AKIRA
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1993
Main classification: H01Q1
IPC codes: H01P1, H01Q1, H01Q21