WO2004042958A1

WO2004042958A1 - Satellite broadcasting repeating apparatus

Info

Publication number: WO2004042958A1
Application number: PCT/KR2002/002064
Authority: WO
Inventors: Tae Sam Yoo
Original assignee: Samwoo Telecommunications Co., Ltd.; Park, Yong, Suk; Kweon, Oh, Seo
Priority date: 2002-11-05
Filing date: 2002-11-06
Publication date: 2004-05-21
Also published as: KR20020090996A; JP2004159283A; KR100502496B1

Abstract

An apparatus for repeating satellite broadcasting includes a low noise amplification portion which separately amplifies satellite signals received from a multi-satellite according to a satellite and a polarization wave, rearranges frequencies of the amplified satellite signals, combines the signals of which frequencies are rearranged by the polarized wave, and outputs the frequency rearranged polarized wave signals, and a transmission antenna portion which receives signals output from the low noise amplification portion and simultaneously retransmits the frequency rearranged polarized wave signals to a subscriber side. Thus, the satellite signals down linked from the multi-satellite can be retransmitted to the subscriber side by using a single satellite broadcasting repeating apparatus through the rearrangement of frequencies so that installation of a system is made easy while providing aesthetic appearance and less complexity. Also, a variety kinds of polarized wave signals can be retransmitted by using a single transmission antenna.

Description

SATELLITE BROADCASTING REPEATING APPRATUS

BACKGROUND OF THE INVENTION

1. Field of the Invention The present invention relates to an apparatus for repeating satellite broadcasting, and more particularly to an apparatus for repeating satellite broadcasting which can broadcast satellite signals down linked from a plurality satellites by using a single satellite broadcasting repeating apparatus.

2. Description of the Related Art Satellites can be classified into communications satellites (CS) and broadcasting satellites (BS). The communications satellites can be classified into local communications satellites, domestic communications satellites, and international communications satellites according to the territorial coverage. Also, the communications satellites can be classified into fixed communications satellites which enable communications between stationary local stations, and mobile communications satellites which enable communications between mobile objects themselves such as vehicles, ships, and airplanes and between mobile objects and stationary stations. The broadcast satellites receive TV broadcasting signal transmitted from local stations, amplify the received signals, and transmit the amplified signals which can be directly received by a parabolic antenna installed at each of houses on the ground.

Low noise blockdown converters (LNB) have the following functions in a satellite broadcasting and communications system.

First is an amplifying function. That is, since output of a signal transmitted from a satellite on a geostationary orbit about 36,000 km remote from the ground is weak, the signal needs amplification. Second is to reduce noise from the received satellite signal. Third is to convert a frequency to be within a range of 950 MHz - 2,150 MHz used in a receiver or set top box since the signal transmitted from the satellite uses a high frequency band of 12 GHz. For example, the LNB converts a signal received from a receiving antenna which is in an SHF band of 3.5 GHz - 12 GHz into an IF signal of 1 GHz and amplifies the converted signal to transmits it to a receiver. The LNB preferably has a low noise figure and largely has the following two functions. First, since the output of a radio wave which has traveled a long distance through the stratosphere and the atmospheric layer from a satellite on a geostationary orbit is reduced, the radio wave needs amplification. That is, the LNB performs the amplification of a signal. Next, the LNB removes a noise signal and noise of the received satellite radio wave. Also, since a satellite radio wave being initially received is within a high frequency band of 3.5 GHz - 12 GHz, the LNB converts the received signal into a frequency in a frequency band of 950 MHz - 2,150 MHz which can be used in a set top box (a satellite signal receiving apparatus).

The LNB is largely classified into two types: a C-band LNB and a KU-band LNB. The C-band LNB converts the frequency of a satellite signal in a C-band into an intermediate frequency that can be received by a receiver and amplifies the signal with a converted frequency. The LNB, or a low noise converter, disposed in front of an antenna before a radio wave of a C-band (3-4 GHz) or KU-band (10-12 GHz) that is transmitted from a satellite is transmitted to a satellite receiver (set top box). The intermediate frequency (IF) corresponds to the frequency of a signal output from the LNB which converts a signal received from a satellite antenna (a parabola antenna) into another frequency (1 GHz) and transmits the converted signal to a tuner (a receiver).

In the meantime, in the area in which high storied buildings or apartments are densely arranged, the satellite signal transmitted from a satellite to be received by a satellite receiving antenna is blocked by the high storied buildings. The area where a down linked broadcasting signal is not received is referred to as a shadow zone. In the shadow zone, the weak satellite signal is received and amplified by using a repeating apparatus and the amplified satellite signal is retransmitted to satellite broadcasting subscribers. Recently, many countries providing satellite broadcasting services have a multi-satellite using the same frequency band. When satellite signals of a multi-satellite are to be retransmitted to receivers by using repeating apparatuss, the technical limit in designing a repeating apparatus lies not in the increase of the number of satellites due to used of the multi-satellite, but in whether the satellites providing services use the same frequency band. For example, there are two cases: the first case in which a single satellite is used and transponders used in the satellite use different polarized waves in the same frequency band, and the second case in which a plurality of satellites provide services with an assigned frequency band. The transponder is an apparatus installed in a communications satellite in data communications performed through a communications satellite. The transponder directly receives a signal transmitted from a transmission station on the ground, amplifies the received signal to an appropriate amplitude, and transmits the signal to a receiving station on the ground. The polarized wave can be classified into a horizontal polarized wave and a vertical polarized wave according to whether the angle between a surface including an amplitude axis of a wave, that is, a polarized surface, and the ground is horizontal or vertical. The horizontal polarized wave is transmitted from an antenna that is an apparatus parallel to the ground and referred to as an H polarized wave. The vertical polarized wave is transmitted from an antenna that is an apparatus perpendicular to the ground and referred to as an V polarized wave. Also, there are a left-hand circular polarization (LHCP) and a right-hand circular polarization (RHCP) according to the form of a radio wave propagating as the polarized surface spirally rotates along the time and the propagation distance. The repeating apparatus has many technical problems in the retransmit in the first case in which satellite signals down linked from the multiple transponders in a single satellite and from the multi-satellite which use different polarized waves in the same frequency band.

Also, up to now, in order to retransmit satellite signals received from the multi-satellite by using a conventional satellite broadcasting repeating apparatus, the number of the repeating apparatus should be increased. However, to install a plurality of repeating apparatuses in a limited area, many problems arise such as increase of an installation cost, worse appearance, and more complexity.

SUMMARY OF THE INVENTION

To solve the above and other problems, the present invention provides an apparatus for repeating satellite broadcasting which can retransmit satellite signals down linked from a multi-satellite formed of a plurality of satellites by minimizing the number of repeating apparatuses. According to one aspect of the present invention, an apparatus for repeating satellite broadcasting comprises a low noise amplification portion which separately amplifies satellite signals received from a multi-satellite according to a satellite and a polarization wave, rearranges frequencies of the amplified satellite signals, combines the signals of which frequencies are rearranged by the polarized wave, and outputs the frequency rearranged polarized wave signals, and a transmission antenna portion which receives signals output from the low noise amplification portion and simultaneously retransmits the frequency rearranged polarized wave signals to a subscriber side. The low noise amplification portion comprises a plurality of low noise amplification ends which separately amplify the satellite signals received from the multi-satellite according to the satellite and the polarized wave, a frequency rearrangement portion which is installed between the low noise amplification ends and rearranges frequency bands of the received satellite signals by mixing the amplified satellite signals with a signal having a predetermined frequency, a band pass filter which allows only a band of the frequency rearranged signal to pass, and a combiner which combines signal bands according to the polarized wave.

The frequency rearrangement portion comprises a voltage controlled oscillator which outputs an oscillation signal having a predetermined frequency, a frequency multiplier which multiplies an oscillation signal output from the voltage controlled oscillator, and a mixer which shifts a frequency band of the satellite signal by mixing the multiplied signal and the satellite signal.

The multi-satellite is one selected from a group consisting of satellites using an L band having a usable frequency band of 1 ,525-1 ,559 MHz, an S band having a usable frequency band of 2,170-2,200 MHz, a C band having a usable frequency band of 3,500-4,200 MHz, an X band having a usable frequency band of 7,250-7,750 MHz, a KU band having a usable frequency band of 10.95-12.75 GHz, a Ku (DBS) band having a usable frequency band of 11.70-12.00 GHz, a Ka band having a usable frequency band of 18.10-21.20 GHz, and an E band having a usable frequency band of 19.70-21.20 GHz, according to a standard of down stream. The transmission antenna portion comprises a first transmission antenna which inputs a signal received through an SMA connector having a first polarized wave signal port into a circular wave guide through a probe disposed parallel to the ground and transmits a radio wave of a first polarized wave, and a second transmission antenna which inputs a signal received through an SMA connector having a second polarized wave signal port into the circular wave guide through a probe disposed perpendicular to the ground and transmits a radio wave of a second polarized wave. Each of the first and second transmission antennas further comprises a dielectric which is provided in the circular wave guide to make a predetermined angle with respect to the ground and forms a circular polarized wave.

The low noise amplification portion further comprises an isolator which makes a system stable and protects a power amplifier by restricting transmitting back a high frequency signal that is input or output back.

An apparatus for repeating satellite broadcasting comprises a low noise amplification portion which separately amplifies satellite signals received from a multi-satellite according to a satellite and a polarization wave, rearranges frequencies of the amplified satellite signals, combines the signals of which frequencies are rearranged by the polarized wave, and outputs the frequency rearranged polarized wave signals, and a transmission antenna portion which receives signals output from the low noise amplification portion and simultaneously retransmits the frequency rearranged polarized wave signals to a subscriber side by using a single antenna.

BRIEF DESCRIPTION OF THE DRAWINGS The above advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which:

FIG. 1 is a view illustrating the structure of a satellite broadcasting repeating system adopting a satellite broadcasting repeating apparatus according to a first preferred embodiment of the present invention;

FIG. 2 is a block diagram illustrating an example of the structure of a low noise amplification portion included in the satellite broadcasting repeating apparatus of FIG. 1 ;

FIGS. 3A and 3B are sectional views for explaining the structure of a circular wave guide in a transmission antenna which can be applied to the satellite broadcasting repeating apparatus of FIG. 1 ; FIG. 4 is a view for explaining the step of rearranging frequency by the satellite broadcasting repeating apparatus according to the first preferred embodiment of the present invention; FIG. 5 is a view illustrating the structure of a satellite broadcasting repeating system adopting a satellite broadcasting repeating apparatus according to a second preferred embodiment of the present invention;

FIG. 6 is a sectional view for explaining the structure of a circular wave guide in a transmission antenna which can be applied to the satellite broadcasting repeating apparatus of FIG. 5;

FIG. 7 is a view illustrating the structure of a satellite broadcasting repeating system adopting a satellite broadcasting repeating apparatus according to a third preferred embodiment of the present invention; FIG. 8 is a block diagram illustrating an example of the structure of a low noise amplification portion included in the satellite broadcasting repeating apparatus of FIG. 7;

FIG. 9 is a block diagram illustrating another example of the structure of a low noise amplification portion included in the satellite broadcasting repeating apparatus of FIG. 7; and

FIG. 10 is a view for explaining the step of rearranging frequency by the satellite broadcasting repeating apparatus according to the third preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 , a satellite broadcasting repeating system adopting a satellite broadcasting repeating apparatus according to a first preferred embodiment of the present invention includes a multi-satellite portion 10 formed of a plurality of satellites 10-1 and 10-2, a satellite broadcasting repeating apparatus 12, a subscriber's receiving portion 14, and a TV 16. The satellite broadcasting repeating apparatus 12 includes a reflection plate 122, a low noise amplification portion 124, and a transmission antenna portion 126. The subscriber's receiving portion 14 includes an LNB 142 and a set top box 144.

The satellite broadcasting repeating apparatus according to the present invention can be designed within the scope of the present invention defined by the accompanying claims to be capable of corresponding to a multi-satellite formed of any combination of satellites using an L band having a usable frequency band of 1 ,525-1 ,559 MHz, an S band having a usable frequency band of 2,170-2,200 MHz, a C band having a usable frequency band of 3,500-4,200 MHz, an X band having a usable frequency band of 7,250-7,750 MHz, a Ku band having a usable frequency band of 10.95-12.75 GHz, a Ku (DBS) band having a usable frequency band of 11.70-12.00 GHz, a Ka band having a usable frequency band of 18.10-21.20 GHz, and an E band having a usable frequency band of 19.70-21.20 GHz, according to a standard of down stream. However, in the present specification, for the convenience of explanation, it is assumed that the frequency bands of down link signals F1 and F2 of the first satellite 10-1 and the second satellite 10-2 use the same frequency band of 12.25 GHz - 12.75 GHz and that signals are down transmitted in a V polarized wave and an H polarized wave from the respective satellites.

According to the present invention, when the signals received from the satellites 10-1 and 10-2 are retransmitted, the frequency band during retransmission is characteristically expanded by shifting the frequency band of the received satellite signal according to the polarized waves. For this, the structure of the low noise amplification portion is altered. Also, the satellite signal can be retransmitted by using a single repeating apparatus with respect to multi-satellites having the same frequency band and different frequency bands. However, in the preferred embodiment of the present invention, for the convenience of explanation, it is assumed that the first and second satellites using a V polarized wave signal and an H polarized wave signal in a frequency band of 12.25 GHz - 12.75 GHz as down link frequencies are used as a multi-satellite.

Referring to FIG. 2, as satellite signals received by the repeating apparatus according to the present invention, there are a V polarized wave signal and an H polarized wave signal received from the first satellite and a V polarized wave signal and an H polarized wave signal received from the second satellite. The V polarized wave signal and H polarized wave signal received from the first satellite SAT1 are separately input to a first low noise amplification portion 210 and a second low noise amplification portion 220, respectively. Also, the H polarized wave signal and the V polarized wave signal received from the second satellite SAT2 are separately input to a third low noise amplification portion 230 and a fourth low noise amplification portion 240, respectively. A power supply portion (not shown) receives a predetermined AC voltage and supplies, for example, a bias voltage having a 15V DC voltage to the low noise amplification portion 124 through a coaxial cable. The first through fourth low noise amplification portions 210, 220, 230, and 240 includes an isolator at each of input ports and output ports and an amplification portion formed of six amplification ports. Preferably, a frequency mixer is arranged after a three step amplification port. The H polarized wave signal from the first satellite is input to the first low noise amplification portion 210 and then is input to the amplification portion 214 through an isolator 212a. The isolators 212a and 212b of the first low noise amplification portion 210 and the isolators of the second through fourth low noise amplification portions 220, 230, and 240 restrict transmitting back of a high frequency signal input to or output from a micro wave type repeating apparatus or satellite communications system, thus stabilizing the system or protecting a power amplifier. A variety of isolators having different feature values, structures, and usable frequency bands can be selectively used.

Next, in the first low noise amplification portion 210, a mixer 217 mixes the H polarized wave signal received from the first satellite and a signal of -500 MHz which is generated from an oscillator 216 and has a reverse phase to the input signal. The frequency band of the H polarized wave signal received from the first satellite is 12.25-12.75 GHz. By mixing the above H polarized wave signal with the signal of -500 MHz (here, "-" means the reverse phase to an input signal.), the H polarized wave signal received from the first satellite in a frequency band of 12.25-12.75 GHz is shifted to a signal in a frequency band of 11.75-12.25 GHz.

Also, in the second low noise amplification portion 220, a mixer 227 mixes the V polarized wave signal received from the first satellite and a signal of -500 MHz which is generated from an oscillator 226 and has a reverse phase to the input signal. The frequency band of the V polarized wave signal received from the first satellite is 12.25-12.75 GHz. By mixing the above H polarized wave signal with the signal of -500 MHz (here, "-" means the reverse phase to an input signal.), the V polarized wave signal received from the first satellite in a frequency band of 12.25-12.75 GHz is shifted to a signal in a frequency band of 11.75-12.25 GHz. Next, in the third low noise amplification portion 230, a PAD 236 delays an input signal by the process delay time in the mixers 217 and 227 and outputs the delayed signal. The frequency band of the H polarized wave signal received from the second satellite is 12.25-12.75 GHz, and the frequency band of the signal output from the PAD 236 maintains the band of 12.25-12.75 GHz which is the same as the frequency band of the H polarized wave signal. Likewise, in the fourth low noise amplification portion 240, a PAD 246 delays an input signal by the process delay time in the mixers 217 and 227 and output the delayed signal. The frequency band of the V polarized wave signal received from the second satellite is 12.25-12.75 GHz, and the frequency band of the signal output from the PAD 246 maintains the band of 12.25-12.75 GHz which is the same as the frequency band of the V polarized wave signal.

Next, band pass filters 218, 228, 238, and 248 perform band-pass filtering of signals amplified by the first through fourth low noise amplification portions 210, 220, 230, and 240 so that signal bands are sufficiently separated.

A first combiner 260 combines the H polarized wave signals output from the first low noise amplification portion 210 and the third low noise amplification portion 230 and outputs the combined H polarized wave signal. That is, the frequency band of the combined H polarized wave signal is 11.75-12.75 GHz. Also, a second combiner 262 combines the V polarized wave signals output from the second low noise amplification portion 220 and the fourth low noise amplification portion 240 and outputs the combined V polarized wave signal. That is, the frequency band of the combined V polarized wave signal is 11.75-12.75 GHz. The combined H polarized wave signal and the combined V polarized wave signal are output through an SMA (sub miniature A) connector (not shown) having two output ports. The SMA connector is referred to as a high performance connector suitable for an application field over 10 GHz.

FIGS. 3A and 3B show the structure of a circular wave guide in the transmission antenna portion 126 which can be adopted in the satellite broadcasting repeating apparatus of FIG. 1. Referring to FIG. 3A, the combined H polarized wave signal received through an SMA connector 302 is input to the circular wave guide through a probe 304 disposed parallel to the ground. The input signal forms a circular polarized wave, for example, an RHCP polarized wave, by a dielectric 306 disposed inclined by 45° to the ground. Referring to FIG. 3B, the signal received through an SMA connector 322 is input to the circular wave guide through a probe 324 disposed perpendicular to the ground. The input signal forms a circular polarized wave, for example, an LHCP polarized wave, by a dielectric 326 disposed inclined by 45° to the ground. When there is no dielectric in the transmission antenna shown in FIGS. 3A and 3B, an antenna which separately transmits the H polarized wave signal and the V polarized wave signal according to polarization can be used.

FIG. 4 shows the operation of rearrangement of a frequency by the satellite broadcasting repeating apparatus according to a preferred embodiment of the present invention. Referring to FIG. 4, the frequency of a satellite signal down linked by the repeating apparatus according to the preferred embodiment of the present invention is arranged such that the frequency band of the first and second satellites use the same band of 12.25-12.75 GHz and each satellite uses the V polarized wave and the H polarized wave. In the repeating apparatus according to the preferred embodiment of the present invention, the frequency band of a signal retransmitted to the subscriber's receiver expands to a frequency band of 11.75-12.75 GHz, as shown in FIG. 4.

Referring back to FIG. 1 , when the dielectric is not inserted in the transmission antenna, the signals F3 and F4 are retransmitted as the V polarized wave signal and H polarized wave signal while maintaining a polarization method of the signal down linked from the satellite. When the dielectric is inserted, the signals F3 and F4 are retransmitted as the LHCP polarized wave signal and the RHCP polarized wave signal. Since the retransmitted signals transmitted from the respective transmission antennas have different polarization methods, no interference exists between the retransmitted signals.

In the above repeating apparatus, the signals input to the low noise amplification portions 210, 220, 230, and 240 are separately input from the respective satellites 10-1 and 10-2 while the signals output from the low noise amplification portion 124 are combined according to polarization of the V polarized wave signal and the H polarized wave signal. In FIG. 1 , the two transmission antennas constituting the transmission antenna portion 126 separately transmit the V polarized wave signal and the H polarized wave signal input through the SMA connector (not shown) to the subscriber. Thus, the repeating apparatus 12 according to the present invention retransmits the satellite signal down linked from the multi-satellite portion 10 to the subscriber by using a single repeating apparatus. The LNB 142 of the subscriber receiver 14 receives the satellite signal retransmitted through the repeating apparatus 12 to amplify the received signal and remove noise and then converts the amplified signal to an intermediate frequency signal within a band which can be used in the set top box 144 using an oscillation frequency as shown in Table 1. The set top box 144 extracts a broadcasting signal by using the intermediate frequency signal and a user can watch satellite broadcasting through the TV 16.

[Table 1]

In the above satellite broadcasting repeating apparatus, the signal are output to the low noise amplification portions 210, 220, 230, and 240, separately from the respective satellites 10-1 and 10-2. However, the signal are output from the low noise amplification portion 124 by being combined according to polarization of the V polarized wave signal and the H polarized wave signal. In FIG. 1 , the two transmission antennas constituting the transmission antenna portion 126 separately transmit to the subscriber the V polarized wave signal and the H polarized wave signal input through the SMA connector (not shown) and an RF cable connected to the SMA connector. Thus, the repeating apparatus 12 according to the preferred embodiment of the present invention retransmits the satellite signal down linked from the multi-satellite portion 10 to the subscriber by using a single repeating apparatus.

Although in the first preferred embodiment the V polarized wave signal and the H polarized wave signal are described to be retransmitted according to the polarization thereof, as can be understood by those skilled in the art, the LHCP signal and the RHCP signal can be retransmitted according to the polarization thereof. The repeating apparatus as in the first preferred embodiment of the present invention can use the conventional retransmission antenna as is. Next, in the satellite broadcasting repeating apparatus according to the second preferred embodiment of the present invention, a variety of polarized wave signals can be retransmitted by using a single transmission antenna by altering the structure of the conventional transmission antenna. FIG. 5 shows the structure of a satellite broadcasting repeating system adopting a satellite broadcasting repeating apparatus according to a second preferred embodiment of the present invention. Referring to FIG. 5, a satellite broadcasting repeating system adopting a satellite broadcasting repeating apparatus according to a second preferred embodiment of the present invention includes a multi-satellite portion 50 formed of a plurality of satellites 50-1 and 50-2, a satellite broadcasting repeating apparatus 52, a subscriber's receiving portion 54, and a TV 56. The satellite broadcasting repeating apparatus 52 includes a reflection plate 522, a low noise amplification portion 524, and a transmission antenna 526. The subscriber's receiving portion 54 includes an LNB 542 and a set top box 544. Since the operations of the satellite broadcasting repeating apparatus 52 and the subscriber's receiving portion 54 according to the second preferred embodiment of the present invention are the same as those described in the first preferred embodiment shown in FIG. 1 , the descriptions thereof will be omitted. However, the transmission antenna 526 of the satellite broadcasting repeating apparatus 52 according to the second preferred embodiment of the present invention includes two input ports receiving a signal amplified by the low noise amplification portion 524 which outputs polarized wave signals through a plurality of output ports.

FIG. 6 shows the structure of a circular wave guide in the transmission antenna which can be applied to the satellite broadcasting repeating apparatus of FIG. 5. Referring to FIG. 6, the V polarized wave signal and the H polarized wave signal received through SMA connectors 602 and 622 are input to the circular wave guide through probes 604 and 624 respectively disposed horizontally and perpendicularly with respect to the ground. The input signals form circular polarized waves, for example, the RHCP polarized wave and the LHCP polarized wave, by dielectric 626 inclined by 45° to the ground. When there is no dielectric in the transmission antennas shown in FIG. 6, the V polarized wave signal and the H polarized wave signal can be transmitted simultaneously through a single transmission antenna according to the polarization of the signals. The satellite broadcasting repeating apparatus using the above improved transmission antenna can be easily installed and requires less installation space.

Next, FIG. 7 shows the structure of a satellite broadcasting repeating system adopting a satellite broadcasting repeating apparatus according to a third preferred embodiment of the present invention. Referring to FIG. 7, a satellite broadcasting repeating system adopting a satellite broadcasting repeating apparatus according to a third preferred embodiment of the present invention includes a multi-satellite portion 70 formed of a plurality of satellites 70-1 and 70-2, a satellite broadcasting repeating apparatus 72, a subscriber's receiving portion 74, and a TV 76. The satellite broadcasting repeating apparatus 72 includes a reflection plate 722, a low noise amplification portion 724, and a transmission antenna 726. The subscriber's receiving portion 74 includes an LNB 742 and a set top box 744.

FIG. 8 shows the structure of the low noise amplification portion included in the satellite broadcasting repeating apparatus shown in FIG. 7. Referring to FIG. 8, as satellite signals input to the repeating apparatus according to the present invention, there are an H polarized wave signal and a V polarized wave signal received from the first satellite and an H polarized wave signal and a V polarized wave signal received from the second satellite. The V polarized wave signal and H polarized wave signal received from the first satellite SAT1 are separately input to a first low noise amplification portion 810 and a second low noise amplification portion 820, respectively. Also, the H polarized wave signal and the V polarized wave signal received from the second satellite SAT2 are separately input to a third low noise amplification portion 830 and a fourth low noise amplification portion 840, respectively. The first through fourth low noise amplification portions 810, 820, 830, and

840 includes an isolator at each of input ports and output ports and an amplification portion formed of six amplification ports. Preferably, a frequency mixer is arranged after a three step amplification port.

The H polarized wave signal from the first satellite is input to the first low noise amplification portion 810 and then is input to the amplification portion 814 through an isolator 812a. The isolators 812a and 812b of the first low noise amplification portion 810 and the isolators of the second through fourth low noise amplification portions 820, 830, and 840 restrict transmitting back a high frequency signal input to or output from a micro wave type repeating apparatus or satellite communications system, thus stabilizing the system or protecting a power amplifier. A variety of isolators having different feature values, structures, and usable frequency bands can be selectively used.

In the first low noise amplification portion 810, a mixer 817 mixes the H polarized wave signal received from the first satellite and a signal of -500 MHz which is generated from an oscillator 816 and has a reverse phase to the input signal. The frequency band of the H polarized wave signal received from the first satellite is 12.25-12.75 GHz. By mixing the above H polarized wave signal with the signal of -500 MHz (here, "-" means the reverse phase to an input signal.), the H polarized wave signal received from the first satellite which is in a frequency band of

12.25-12.75 GHz is shifted to a signal in a frequency band of 11.75-12.25 GHz.

Also, in the second low noise amplification portion 820, a PAD 826 delays an input signal by the process delay time in the mixer 817 and outputs the delayed signal. The frequency band of the V polarized wave signal received from the first satellite is 12.25-12.75 GHz, and the frequency band of the signal output from the PAD 826 maintains the band of 12.25-12.75 GHz which is the same as the frequency band of the V polarized wave signal.

Also, in the third low noise amplification portion 830, a mixer 837 mixes the H polarized wave signal received from the second satellite and a signal of -1500 MHz which is generated from an oscillator 836 and has a reverse phase to the input signal. The frequency band of the H polarized wave signal received from the second satellite is 12.25-12.75 GHz. By mixing the above H polarized wave signal with the signal of -1500 MHz (here, "-" means the reverse phase to an input signal.), the H polarized wave signal received from the second satellite which is in a frequency band of 12.25-12.75 GHz is shifted to a signal in a frequency band of 10.75-11.25 GHz.

Also, in the fourth low noise amplification portion 840, a mixer 847 mixes the V polarized wave signal received from the second satellite and a signal of -1000 MHz which is generated from an oscillator 846 and has a reverse phase to the input signal. The frequency band of the V polarized wave signal received from the second satellite is 12.25-12.75 GHz. By mixing the above V polarized wave signal with the signal of -1000 MHz (here, "-" means the reverse phase to an input signal.), the V polarized wave signal received from the second satellite which is in a frequency band of 12.25-12.75 GHz is shifted to a signal in a frequency band of 11.25-11.75 GHz.

Next, band pass filters 818, 828, 838, and 848 perform band-pass filtering of signals amplified by the first through fourth low noise amplification portions 810, 820, 830, and 840 so that signal bands are sufficiently separated.

A first combiner 860 combines the H polarized wave signal output from the first low noise amplification portion 810 and the V polarized wave signal output from the second low noise amplification portion 820. A second combiner 862 combines the H polarized wave signal output from the third low noise amplification portion 830 and the V polarized wave signal output from the fourth low noise amplification portion 840. A third combiner 870 combines the output signal of the first combiner 860 and the output signal of the second combiner 862. The frequency band of the combined signal by the third combiner 870 is 10.75-12.75 GHz which is a relatively wide band. The combined signal is output through an SMA connector having a single output port.

FIG. 9 shows another example of the structure of the low noise amplification portion included in the satellite broadcasting repeating apparatus shown in FIG. 7. Referring to FIG. 9, a signal generating portion 902 generates a signal having a frequency of 100 MHz by using, for example, a phase locked loop (PLL) circuit and a voltage controlled oscillator (VCO). First, second, and third frequency multipliers 904, 906, and 908 generate signals of 500 MHz, 1000 MHz, and 1500 MHz by multiplying the frequency of the 100 MHz signal generated by the signal generating portion 902 respectively by 5 times, 10 times, and 15 times. When the generated signals are multiplied by the satellite signals received from the respective satellites, the frequencies of the satellite signals are rearranged.

FIG. 10 shows the process of rearrangement of the frequencies by the satellite broadcasting repeating apparatus according to the third preferred embodiment of the present invention. Referring to FIG. 10, in the rearrangement of the frequencies of the satellite signals down linked from the multi-satellite to the satellite broadcasting repeating apparatus according to the present invention, the frequency bands of the first and second satellites use the same band of 12.25-12.75 GHz and the respective satellites use the V polarized wave and the H polarized wave. The frequency band of a signal retransmitted from the repeating apparatus according to the preferred embodiment of the present invention to the subscriber's receiver expands to a frequency band of 10.75-12.75 GHz.

[Table 2]

The LNB 742 receives the satellite signal retransmitted through the repeating apparatus 72, amplifies the received satellite signal, removes noise from the amplified satellite signal, and converts the satellite signal to an intermediate frequency signal in a band which can be used by the set top box 744 by using a local oscillation frequency as shown in Table 2. The set top box 744 extracts a broadcasting signal by using the intermediate frequency signal. Thus, a user can watch satellite broadcasting provided by the multi-satellites through the TV 76.

Although in the above-described preferred embodiments arbitrary satellites using the V polarized wave signal and the H polarized wave signal in a frequency band of 12.25-12.75 GHz are used as the multi-satellite, the satellite broadcasting repeating apparatus according to the present invention can be designed within the scope of the present invention defined by the accompanying claims to be capable of corresponding to a multi-satellite formed of any combination of satellites using an L band having a usable frequency band of 1 ,525-1 ,559 MHz, an S band having a usable frequency band of 2,170-2,200 MHz, a C band having a usable frequency band of 3,500-4,200 MHz, an X band having a usable frequency band of 7,250-7,750 MHz, a Ku band having a usable frequency band of 10.95-12.75 GHz, a Ku (DBS) band having a usable frequency band of 11.70-12.00 GHz, a Ka band having a usable frequency band of 18.10-21.20 GHz, and an E band having a usable frequency band of 19.70-21.20 GHz, according to a standard of down stream. That is, while this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

As described above, in the satellite broadcasting repeating apparatus according to the present invention, the satellite signals down linked from the multi-satellite can be retransmitted to the subscriber side by using a single satellite broadcasting repeating apparatus through the rearrangement of frequencies. Thus, the present invention makes installation easy, provides aesthetic appearance, lessens complexity. Also, a variety kinds of polarized wave signals can be retransmitted by using a single transmission antenna.

Claims

What is claimed is:

1. An apparatus for repeating satellite broadcasting comprising: a low noise amplification portion which separately amplifies satellite signals received from a multi-satellite according to a satellite and a polarization wave, rearranges frequencies of the amplified satellite signals, combines the signals of which frequencies are rearranged by the polarized wave, and outputs the frequency rearranged polarized wave signals; and a transmission antenna portion which receives signals output from the low noise amplification portion and simultaneously retransmits the frequency rearranged polarized wave signals to a subscriber side.

2. The apparatus as claimed in claim 1 , wherein the low noise amplification portion comprises: a plurality of low noise amplification ends which separately amplify the satellite signals received from the multi-satellite according to the satellite and the polarized wave; a frequency rearrangement portion which is installed between the low noise amplification ends and rearranges frequency bands of the received satellite signals by mixing the amplified satellite signals with a signal having a predetermined frequency; a band pass filter which allows only a band of the frequency rearranged signal to pass; and a combiner which combines signal bands according to the polarized wave.

3. The apparatus as claimed in claim 2, wherein the frequency rearrangement portion comprises: a voltage controlled oscillator which outputs an oscillation signal having a predetermined frequency; a frequency multiplier which multiplies an oscillation signal output from the voltage controlled oscillator; and a mixer which shifts a frequency band of the satellite signal by mixing the multiplied signal and the satellite signal.

4. The apparatus as claimed in claim 1 , wherein the multi-satellite is one selected from a group consisting of satellites using an L band having a usable frequency band of 1 ,525-1 ,559 MHz, an S band having a usable frequency band of 2,170-2,200 MHz, a C band having a usable frequency band of 3,500-4,200 MHz, an X band having a usable frequency band of 7,250-7,750 MHz, a Ku band having a usable frequency band of 10.95-12.75 GHz, a Ku (DBS) band having a usable frequency band of 11.70-12.00 GHz, a Ka band having a usable frequency band of 18.10-21.20 GHz, and an E band having a usable frequency band of 19.70-21.20 GHz, according to a standard of down stream.

5. The apparatus as claimed in claim 1 , wherein the transmission antenna portion comprises: a first transmission antenna which inputs a signal received through an SMA connector having a first polarized wave signal port into a circular wave guide through a probe disposed parallel to the ground and transmits a radio wave of a first polarized wave; and a second transmission antenna which inputs a signal received through an SMA connector having a second polarized wave signal port into the circular wave guide through a probe disposed perpendicular to the ground and transmits a radio wave of a second polarized wave.

6. The apparatus as claimed in claim 5, wherein each of the first and second transmission antennas further comprises a dielectric which is provided in the circular wave guide to make a predetermined angle with respect to the ground and forms a circular polarized wave.

7. The apparatus as claimed in claim 1 , wherein the low noise amplification portion further comprises an isolator which makes a system stable and protects a power amplifier by restricting transmitting back a high frequency signal that is input or output back.

8. An apparatus for repeating satellite broadcasting comprising: a low noise amplification portion which separately amplifies satellite signals received from a multi-satellite according to a satellite and a polarization wave, rearranges frequencies of the amplified satellite signals, combines the signals of which frequencies are rearranged by the polarized wave, and outputs the frequency rearranged polarized wave signals; and a transmission antenna portion which receives signals output from the low noise amplification portion and simultaneously retransmits the frequency rearranged polarized wave signals to a subscriber side by using a single antenna.

9. The apparatus as claimed in claim 8, wherein the transmission antenna portion comprises: a first SMA connector having a first polarized wave signal port; a first probe disposed parallel to the ground and inputs a signal received through the first SMA connector into a circular wave guide; a second SMA connector having a second polarized wave signal port; a second probe disposed perpendicular to the ground and inputs a signal received through the second SMA connector into the circular wave guide.

10. The apparatus as claimed in claim 9, wherein the transmission antenna further comprises a dielectric which is provided in the circular wave guide to make a predetermined angle with respect to the ground and forms a circular polarized wave.