Patent Publication Number: US-6661374-B2

Title: Base transceiver station having multibeam controllable antenna system

Description:
FIELD OF THE INVENTION 
     The present invention relates to a base transceiver station in a radio communication system; and, more particularly, to a base transceiver station having a multi-beam controllable antenna system in a radio communication system, which varies a horizontal/vertical angle and a tilting angle according to variation in an amount of traffic within a sector. 
     DESCRIPTION OF THE PRIOR ART 
     From now on, a radio communication should support not only a voice service but also a high speed multimedia service including a data communication, a video transmission service, etc. However, radio resources necessary for the radio communication are limited. Therefore, various methods for effectively reusing the radio resources are being developed. 
     In general, a radio communication system includes a mobile switching center (MSC), a base station controller (BSC), a plurality of base transceiver stations (BTS) and a plurality of mobile stations (MS). 
     The MSC controls a plurality of the BSCs each controlling a plurality of the BTSs. 
     A signal radiated from the MS located in a service coverage of the BTS is transmitted to the MSC through the BTS and the BSC. On the contrary, a signal from the MSC is transmitted to the MS through the BSC and the BTS. Here, the BTS communicates with the MS through the radio resource and does with the BSC through the wired resource. 
     The BSC performs a connection between the BTS and the MSC and a signal processing for a communication between the BTS and the MSC. 
     The MSC performs a call processing of a subscriber, a call setup/release and functions for providing value added services. 
     FIG. 1 shows a conventional base transceiver station. 
     Referring to FIG. 1, the conventional base transceiver station includes fixed combiners  101 - 1  to  101 - 3 , fixed dividers  103 - 1  to  103 - 3 , amplifiers  105 - 11  to  105 - 34 , combiners  107 - 1  to  107 - 3  and duplexers  109 - 1  to  109 - 3 . 
     A service area of the BTS is divided into multiple sectors, and frequency assignments assigned to the BTS are re-assigned to the multiple sectors. The frequency assignment assigned to each sector is fixed in order to be used only for the sector. 
     In general, a beam pattern of an antenna is set to be wider than the service area as shown in FIG.  2 A. 
     Referring to FIG. 2B, the FAs in each of the sectors are overlapped with each other, efficiency of frequency is considerably decreased in the overlapped region (denoted by oblique lines). 
     Since the mobile station always moves, distribution of subscribers in the service areas, i.e., a cell or a sector, always varies. However, a horizontal half-power beam width and a tilting angle of an antenna system located in the BTS are fixed and cannot be varied. 
     Therefore, though traffics in a certain sector is temporarily increased, the frequency assignments cannot be changed, thereby decreasing efficiency in use of the frequency resources. 
     In general, the antenna is located on a high location, which is remote from the BTS, and the antenna is coupled to the BTS by using a radio frequency (RF) cable. There is a transmission loss in the long RF cable. As the RF cable is longer, the transmission loss becomes larger. 
     There are a conventional mechanical down-tilting antenna system and a conventional electrical down-tilting antenna system. The mechanical down-tilting antenna system being capable of mechanically down-tilting a beam radiated from an antenna incorporated into the antenna system. The antenna is mounted atop a mast at a height above ground, e.g., in many cases about 200 feet. 
     In case when the orientation of a radiation beam is steered downward, the antenna must be mechanically down tilted. One of the major shortcomings is that this approach is generally regarded as too rigid and too expensive. There is an approach that electrically down-tilting the radiation beam is performed by steering the relative phases of the radiation associated with each of several radiators of an antenna. 
     The conventional electrical down-tilting antenna being capable of electrically down-tilting a beam  406  radiated from an antenna array incorporated into the antenna system. In the antenna system, the antenna array incorporates therein an array of radiators and a single point signal feed network provided with a scan network to couple the single point signal feed network to the antenna array of radiators. The scan network includes a plurality of transmission lines between the feed network and each radiator. Among these electrical down tilting method is a capacitive coupling method, in which an adjustable capacitance is placed in series with the transmission lines to provide a plurality of signals to each radiator of the antenna array, thus causing the desired phase shifts. A phase shifter is associated with each radiator of the antenna array such that the phase shifted beam from each radiator constructively interferes with the beam from every other radiator to produce a composite beam radiating at an angle from a line normal to the surface of the antenna. By changing the phase shift provided by each phase shifter, the beam can be scanned across the antenna surface. Another such approach is to use different lengths of transmission lines for feeding the different elements to produce a permanent electrical down tilting. 
     There are a number of problems associated with the above-described antenna systems. First of all, both of the antenna systems cannot steer a radiation beam in horizontal direction. 
     Another problem of the conventional antenna system is that it requires a number of phase shifters corresponding to the number of the transmission lines in the conventional antenna systems. 
     In addition, in the conventional antenna systems, it requires a mechanically complex, for example using a rack and pinion assembly or a number of phase shifters corresponding to the number of radiators, for providing the desired phase shift. 
     Further, the conventional antenna systems cannot steer a beam width in horizontal and in vertical, 
     Finally, because a beam is scanned in vertical and in horizontal by utilizing the conventional antenna systems, it has too much scan loss. 
     Therefore, in order to keep an output power of a signal radiated from the antenna constant, an output power of a multi channel power amplifier (MCPA) in the BTS should be increased. 
     Since the MCPA is an expensive device, a high capacity MCPA makes the cost for the BTS increased. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide an antenna system capable of controlling multi beams of frequency assignments by independently varying a half-power beam width and a tilting angle in vertical and horizontal direction. 
     It is another object of the present invention to provide a method and a base transceiver station for controlling multi beams of frequency assignments by independently varying a half-power beam width and a tilting angle in vertical and horizontal direction. 
     It is another object of the present invention to provide an antenna system for electrically steering a beam emitted therefrom in horizontal by using a multi-line phase shifter. 
     It is another object of the present invention to provide an antenna system for selectively switching a beam width in horizontal by using a switchable divider. 
     It is another object of the present invention to provide an antenna system for minimizing interference and maximizing cell capacity. 
     It is another object of the present invention to provide an antenna system for providing an optimal cell planning and meeting the real world of diverse environments. 
     It is another object of the present invention to provide an antenna system capable of harmonizing with communication environment. 
     It is another object of the present invention to provide an antenna system with a stable installation. 
     In accordance with an aspect of the present invention, there is provided an antenna system for controlling multi beams of a transmission signal, comprising; at least one first dividing unit for dividing an input signal into a plurality of first divided signals; at least one first phase shifting unit for shifting the first divided signals and generating first phase-shifted signals, at least one first combining unit for combining the phase-shifted signals and generating a first combined signal; at least one second dividing unit for dividing the first combined signal into second divided signals; at least one second phase shifting unit for shifting the second divided signals and generating second phase-shifted signals; and a controlling unit for generating a control signal which controls horizontal and vertical half-power beam widths and tilting angles of the input signal independently by controlling the first and the second dividing unit and the first and the second phase shifting unit. 
     In accordance with another aspect of the present invention, there is provided an antenna system for receiving a signal, comprising: at least one dividing unit for dividing a signal received by the antenna array into a plurality of divided signals; at least one phase shifting unit for controlling phases of the divided signals and generating phase-shifted signals; a combining unit for combining the phase-shifted signals, generating a combined signal and outputting the combined signal; and a controlling unit for generating a control signal which controls the phase shifting unit and the combining unit. 
     In accordance with further another aspect of the present invention, there is provided a base transceiver station for controlling multi beams of a transmission signal, comprising: at least one first dividing unit for dividing an input signal into a plurality of first divided signals; at least one first phase shifting unit for shifting the first divided signals and generating first phase-shifted signals; at least one first combining unit for combining the phase-shifted signals and generating a first combined signal; at least one second dividing unit for dividing the first combined signal into second divided signals; at least one second phase shifting unit for shifting the second divided signals and generating second phase-shifted signals; and a controlling unit for generating a control signal which controls horizontal and vertical half-power beam widths and tilting angles of the input signal independently by controlling the first and the second dividing unit and the first and the second phase shifting unit. 
     In accordance with further another aspect of the present invention, there is provided a base transceiver station for receiving a signal, comprising: at least one dividing unit for dividing a signal received by the antenna array into a plurality of divided signals; at least one phase shifting unit for controlling phases of the divided signals and generating phase-shifted signals; a combining unit for combining the phase-shifted signals, generating a combined signal and outputting the combined signal; and a controlling unit for generating a control signal which controls the phase shifting unit and the combining unit. 
     In accordance with further another aspect of the present invention, there is provided a method for controlling multi beams of a transmission signal in an antenna system, comprising the steps of: a) at first dividing unit, dividing an input signal into a plurality of first divided signals; b) at first phase shifting unit, shifting the first divided signals and generating first phase-shifted signals; c) at first combining unit, combining the phase-shifted signals and generating a first combined signal; d) at second dividing unit, dividing the first combined signal into a plurality of second divided signals; e) at second phase shifting unit, shifting the second divided signals and generating second phase-shifted signals; and f) generating a control signal which controls horizontal and vertical half-power beam widths and tilting angles of the input signal independently by controlling the first and the second dividing unit and the first and the second phase shifting unit. 
     In accordance with further another aspect of the present invention, there is provided a method for controlling multi beams of a received signal in an antenna system, comprising the steps of: a) at dividing unit, dividing a signal received by the antenna array into a plurality of divided signals; b) at phase shifting unit, controlling phases of the divided signals and generating phase-shifted signals; c) at combining unit, combining the phase-shifted signals, generating a combined signal and outputting the combined signal; and d) generating a control signal which controls the phase shifting unit and the combining unit. 
     In accordance with further another aspect of the present invention, there is provided a method for controlling multi beams of a transmission signal in a base transceiver station, comprising the steps of: a) at first dividing unit, dividing an input signal into a plurality of first divided signals; b) at first phase shifting unit, shifting the first divided signals and generating first phase-shifted signals; c) at first combining unit, combining the phase-shifted signals and generating a first combined signal; d) at second dividing unit, dividing the first combined signal into a plurality of second divided signals; e) at second phase shifting unit, shifting the second divided signals and generating second phase-shifted signals; and f) generating a control signal which controls horizontal and vertical half-power beam widths and tilting angles of the input signal independently by controlling the first and the second dividing unit and the first and the second phase shifting unit. 
     In accordance with further another aspect of the present invention, there is provided a method for controlling multi beams of a received signal in a base transceiver station, comprising the steps of: a) at dividing unit, dividing a signal received by the antenna array into a plurality of divided signals; b) at phase shifting unit, controlling phases of the divided signals and generating phase-shifted signals; c) at combining unit, combining the phase-shifted signals, generating a combined signal and outputting the combined signal; and d) generating a control signal which controls the phase shifting unit and the combining unit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which: 
     FIG. 1 shows a diagram of a conventional base transceiver station; 
     FIGS. 2A and 2B depict beam patterns for beams emitted from a conventional antenna system; 
     FIG. 3 is a block diagram showing an antenna system in accordance with the present invention; 
     FIG. 4 is a block diagram showing a structure of a switching block in an antenna system; 
     FIG. 5 is a block diagram showing a structure of an outgoing signal adjusting block in an antenna system; 
     FIG. 6 is a block diagram showing a structure of an incoming signal adjusting block in an antenna system; 
     FIG. 7 is a block diagram showing a structure of a control block in an antenna system; 
     FIG. 8 is a block diagram showing an antenna array in transmitting signals out of an antenna system; 
     FIG. 9 illustrates a block diagram of an antenna array in receiving signals from the outside of the antenna system; 
     FIG. 10 illustrates a diagram of a switchable divider included in a switching block in an antenna system; 
     FIG. 11 illustrates a relationship of signal transmission/reception between a switchable divider block and a first phase shifter block; 
     FIG. 12 illustrates a relationship of signal transmission/reception between a first phase shifter and its neighbor elements; 
     FIG. 13 illustrates a relationship of signal transmission/reception between a combiner/divider block and a first phase shifter block; 
     FIG. 14 illustrates a relationship of signal transmission/reception between a second phase shifter and its neighbor elements; 
     FIG. 15 is a schematic representation of a beam from an antenna system carried out a down-tilt in accordance with the present invention; 
     FIG. 16A plots a beam pattern for electrically down tilting a beam emitted from an antenna system in accordance with the present invention; 
     FIG. 16B plots a beam pattern for horizontally steering a beam emitted from an antenna system in accordance with the present invention; 
     FIG. 16C plots a beam pattern for horizontally switching a beam width emitted from an antenna system in accordance with the present invention; 
     FIGS. 17A and 17B show diagrams of an antenna system capable of controlling multi beams of frequency assignments (FA) independently in accordance with the present invention; 
     FIGS. 18A and 18B show diagrams of an antenna system when horizontal half-power beam widths are all 30 degrees in accordance with the present invention; 
     FIG. 19 depicts the horizontal half-power beam widths of the FAs emitted from the antenna system of FIGS. 18A and 18B; 
     FIGS. 20A and 20B diagrams of an antenna system when horizontal half-power beam widths are 90, 60 and 30 degrees in accordance with the present invention; 
     FIG. 21 depicts the horizontal half-power beam widths of the FAs emitted from the antenna system of FIGS. 20A and 20B; 
     FIG. 22 depicts the horizontal half-power beam widths of the FAs emitted from the antenna system when the horizontal half-power beam widths and the vertical tilting angles of the FA 2 , FA 3  and FA 4  are controlled so as to deal with the traffic increase in a certain area within a sector; 
     FIGS. 23A and 23B are diagrams of an antenna system when horizontal half-power beam widths are 90, 60 and 30 degrees and output signals of a second horizontal half-power beam width controlling switchable divider are controlled so as to be inputted to a second and a third fixed combiners; and 
     FIG. 24 shows the horizontal half-power beam widths of the FAs emitted from the antenna system when the horizontal half-power beam widths and the vertical tilting angles are controlled independently. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, referring to FIGS. 3 to  16 C, an antenna system  100  for controlling a single beam in a radio communication in accordance with preferred embodiments of the present invention. 
     In FIG. 3, there is provided a block diagram of an antenna system  100  for use in a radio communication system. The antenna system  100  comprises a switching block  110 , a signal adjusting block  120  including an outgoing signal adjusting block  122  and an incoming signal adjusting block  124 , and an antenna array  130  of P×Q radiators. Here, P and Q are positive integers, respectively. The antenna system  100  further comprises a control block  700  including a beam control board  710 , a vertical motor driver  720  and a horizontal motor driver  730  (shown in FIG.  7 ). 
     FIG. 4 is a block diagram showing a structure of a switching block in an antenna system. 
     The switching block  110  includes a first switching block  410 , an up/down converting block  420  and a second switching block  430 . 
     The first switching block  410  includes a first switch  412  and a second switch  414 . 
     The first switch  412  receives a first communication signal O 100  from the exterior thereof and transmits one or more first frequency signals, e.g., FA 1 _TX, FA 2 _TX . . . FA(N−1)_TX and FAN_TX separately to the up/down converting block  420  through respective output terminals thereof. The first frequency signals, FA 1 _TX, FA 2 _TX . . . FA(N−1)_TX and FAN_TX are based on the received first communication signal O 100  and have, respectively, a different frequency. The second switch  414  receives one or more second frequency signals, e.g., FA 1 _RX, FA 2 _RX . . . FA(N−1)_RX and FAN_RX from the up/down converting block  420  and transmits a second communication signal I 400  to the exterior thereof through its output terminal. The second frequency signals, FA 1 _RX, FA 2 _RX . . . FA(N−1)_RX and FAN_RX have, respectively, a different frequency. The second communication signal I 400  is generated based on the second frequency signals received from the up/down converting block  420 . 
     As shown in this drawing, the up/down converting block  420  includes a multitude of up/down converters  422 - 1 ,  422 - 2  . . .  422 -(N−1) and  422 -N. At this point, the number of the up/down converters depends on how many frequency signals are received/transmitted from/to the first switching block  410 . In other words, the number of the up/down converters is equal to that of the frequency signals received/transmitted from/to the first switching block  410 . 
     Each up/down converter performs an up/down conversion process for signals inputted to therein, 
     For example, when the up/down converting block  420  receives the first frequency signals from the first switch  412  of the first switching block  410 , each up/down converter of the up/down converting block  420  performs the up/down conversion process for each of the first frequency signals corresponding thereto. Then, one or more third frequency signals that are generated according to the up/down conversion process are supplied to a third switch  432  of the second switching block  430 . 
     On the contrary, when the up/down converting block  420  receives one or more fourth frequency signals from a fourth switch  434  of the second switching block  430 , each up/down converter of the up/down converting block  420  performs the up/down conversion process for each of the fourth frequency signals corresponding thereto. Then, the second frequency signals that are generated according to the up/down conversion process are supplied to the second switch  414  of the first switching block  410 . 
     The second switching block  430  includes the third switch  432  and the fourth switch  434 . 
     The third switch  432  receives the third frequency signals from the up/down converting block  420  and transmits third communication signals O 200  separately to the outgoing signal adjusting block  122  (shown in FIG.  3 ). The third frequency signals include FA 1 _TX, FA 2 _TX . . . FA(N−1)_TX and FAN_TX for which the up/down conversion process are performed. 
     The fourth switch  434  receives second adjusted signals I 300  from the incoming signal adjusting block  124  (shown in FIG. 3) and transmits the fourth frequency signals correspondingly to the respective converters of the up/down converting block  420 . The fourth frequency signals include FA 1 _RX, FA 2 _RX . . . FA(N−1)_RX and FAN_RX for which the up/down conversion process are to be performed. 
     FIG. 5 is a block diagram showing a structure of an outgoing signal adjusting block in an antenna system. 
     The outgoing signal adjusting block  122  receives the group of the second communication signals O 200  such as FA 1 _TX signal . . . and FAN_TX signal which are transmitted from the third switch  432 . After adjusting the received signals O 200 , it transmits one or more first adjusted signals O 300  to the antenna array  130 . 
     As shown in FIG. 5, the outgoing signal adjusting block  122  includes one or more blocks of switchable dividers  510 - 1 ,  510 - 2  . . .  510 -(N−1) and  510 -N, one or more blocks of first phase shifters (P/S)  520 - 1 ,  520 - 2  . . .  520 -(N−1) and  520 -N, one or more blocks of first combiners/dividers (C/D)  530 - 1 ,  530 - 2  . . .  530 -(N−1) and  530 -N, and one or more blocks of second phase shifters (P/S)  540 - 1 ,  540 - 2  . . .  540 -(N−1) and  540 -N. 
     At this point, the number of each block of the switchable dividers, the first phase shifters, the first combiners/dividers and the second phase shifters is equal to the number of the up/down converters included in the up/down converting block  420 . 
     Each block of switchable dividers  510 - 1  to  510 -N includes P number of switchable dividers. As shown in this drawing, for example, a first block of switchable dividers  510 - 1  includes P number of switchable dividers  510 - 1 - 1  to  510 - 1 -P. 
     Each block of first phase shifters  520 - 1  to  520 -N includes P number of first phase shifters. For example, a first block of first phase shifters  520 - 1  includes P number of first phase shifters  520 - 1 - 1  to  520 - 1 -P. 
     Each block of first combiners/dividers (C/D)  530 - 1  to  530 -N includes Q number of first C/Ds. For example, a first block of first C/Ds  530 - 1  includes Q number of first C/Ds  530   1 - 1  to  530 - 1 -Q. 
     Each block of second phase shifters (P/S)  540 - 1  to  540 -N includes Q number of second P/Ss. For example, a first block of second P/Ss  540 - 1  includes Q number of second P/Ss  540 - 1 - 1  to  540 - 1 -Q. 
     FIG. 6 is a block diagram showing a structure of an incoming signal adjusting block in an antenna system. 
     The incoming signal adjusting block  124  receives one or more fourth communication signals I 200  from the antenna array  130 . After adjusting the same, it transmits second adjusted signals I 300  such as FA 1 _RX signal . . . and FAN_RX signal to the fourth switch  434  of the second switching block  430 . 
     As shown in FIG. 6, the incoming signal adjusting block  124  includes one or more blocks of switchable combiners  610 - 1 ,  610 - 2  . . .  610 -(N−1) and  610 -N, one or more blocks of third phase shifters (P/S)  620 - 1 ,  620 - 2  . . .  620 -(N−1) and  620 -N, one or more blocks of second combiners/dividers (C/D)  630 - 1 ,  630 - 2  . . .  630 -(N−1) and  630 -N, and one or more blocks of fourth phase shifters (P/S)  640 - 1 ,  640 - 2  . . .  640 -(N−1) and  640 -N. 
     At this point, the number of each block of the switchable combiners, the third phase shifters, the second combiners/dividers and the fourth phase shifters is equal to the number of the up/down converters included in the up/down converting block  420 . 
     Each block of switchable combiners  610 - 1  to  610 -N includes P number of switchable combiners. As shown in this drawing, for example, a first block of switchable combiners  610 - 1  includes P number of switchable combiners  610 - 1 - 1  to  610 - 1 -P. 
     Each block of third phase shifters  620 - 1  to  620 -N includes P number of third phase shifters. For example, a first block of third phase shifters  620 - 1  includes P number of third phase shifters  620 - 1 - 1  to  620 - 1 -P. 
     Each block of second combiners/dividers (C/D)  630 - 1  to  630 -N includes Q number of second C/Ds. For example, a first block of second C/Ds  630 - 1  includes Q number of second C/Ds  630 - 1 - 1  to  630 - 1 -Q. 
     Each block of fourth phase shifters (P/S)  640 - 1  to  640 -N includes Q number of fourth P/Ss. For example, a first block of fourth P/Ss  640 - 1  includes Q number of fourth P/Ss  640 - 1 - 1  to  640 - 1 -Q. 
     FIG. 7 is a block diagram showing a structure of a control block in an antenna system. 
     The control block  700  includes a beam control board  710 , a horizontal motor driver  720  and a vertical motor driver  730 . 
     When a control signal is inputted to the beam control board  710  through a control port thereof, the beam control board  710  generates a first control signal S 10 , a second control signal S 20  and a third control signal S 30 . The first control signal S 10  is used for horizontal beam width switching (HBWSw), the second control signal S 20  is used for horizontal beam steering (HBSt) and the third control signal S 30  is used for vertical beam down titling (VBDT). 
     FIGS. 8 and 9 are block diagrams each showing an antenna array in an antenna system. 
     Particularly, FIG. 8 shows an antenna array in transmitting signals out of an antenna system and FIG. 9 shows the antenna array in receiving signals from the outside of the antenna system thereto. 
     The antenna array  130  of P×Q radiators, wherein P and Q are positive integers, respectively. 
     Referring to FIG. 8, the antenna array  130  receives one or more first adjusted signals O 300  from the outgoing signal adjusting block  122  and then transmits the adjusted signals O 300  out of the antenna system. 
     In case where the antenna array  130  receives the first adjusted signals O 300  from the outgoing signal adjusting block  122 , the first adjusted signals are transmitted out of the antenna system through corresponding P number of radiators included in each of the columns C 1  to C Q . 
     For example, parts of the adjusted signals O 300 , W 41 , (W+1) 41  . . . (W+N−2) 41  and (W+N−1) 41  from respective phase shifters  540 - 1 - 1 ,  540 - 2 - 1  . . .  540 -(N−1)- 1  and  540 -N- 1  are radiated through the radiators included in the column C 1 . Also, another parts of the adjusted signals O 300 , W 4 Q, (W+1) 4 Q . . . (W+N−2) 4 Q and (W+N−1) 4 Q from respective phase shifters  540 - 1 -Q,  540 - 2 -Q . . .  540 -(N−1)-Q and  540 -N-Q are radiated through the radiators included in the column C Q . 
     Referring to FIG. 9, the antenna array  130  receives a plurality of radio signals from the exterior of the antenna system and then transmits the radio signals to the incoming signal adjusting block  124 . 
     For example, parts of the fourth communication signals I 200  from the outside of the system, E 41 , (E+1) 41  . . . (E+N−2) 41  and (E+N−1) 41  are transmitted to the respective phase shifters  640 - 1 - 1 ,  640 - 2 - 1  . . .  640 -(N−1)- 1  and  640 -N- 1 , wherein the parts of the signals are received through the radiators included in the column C 1 . Also, another parts of the fourth communication signals I 200 , E 4 Q, (E+1) 4 Q . . . (E+N2) 4 Q and (E+N−1) 4 Q are transmitted to the respective phase shifters  640 - 1 -Q,  640 - 2 -Q . . .  640 -(N−1)-Q and  640 -N-Q through the radiators included in the column C Q . 
     FIG. 10 illustrates a switchable divider included in a switching block in an antenna system. 
     Let the switchable divider shown in this drawing represent a switchable divider  510 - 1 - 1  included in the first block of switchable dividers  510 - 1 . 
     The switchable divider  510 - 1 - 1  includes an input port RX 1  for receiving an RF signal from the input port, first transmission lines  44   11 - 44   1Q , second transmission lines  46   11 - 46   1Q , isolation resistors  45   11 - 45   1Q , output ports TX 11 -TX 1Q , a first switch  41  and a second switch  42 . The switchable divider  510 - 1 - 1  is described in a Q-way operating mode. In the preferred embodiment, the switchable divider  510 - 1 - 1  operates as a divider to equally divide the RF signal into Q number of output signals at a maximum operating mode. The switchable divider  510 - 1 - 1  can vary its operating rode based on the first control signal S 10  from the beam control board  710 . The switchable divider  510 - 1 - 1  is described in detail in U.S. Pat. No. 5,872,491 issued Feb. 16, 1999 and owned by the same applicant, which is incorporated herein by reference. 
     Referring back to FIGS. 5 and 7, each of the switchable dividers  510 - 1 - 1  to  510 - 1 -P provides a plurality of divided signals to the first P/Ss  520 - 1 - 1  to  520 - 1 -P through lines W 11  to W 1 P, respectively. In each of the switchable dividers  510 - 1 - 1  to  510 - 1 -P, the number of divided signals is equal to that of the operating modes. In the preferred embodiment, the antenna system  100  can modulate a beam width emitting from its antenna array  130  by changing the number of operating modes. The simulation data are shown in FIGS. 16A to  16 C. 
     On the other hand, the horizontal motor driver  720  generates P number of motor control signals in response to the second control signal S 20  from the beam control board  710 . Each motor control signal (S 40  shown in FIG. 7) is inputted to a corresponding first P/S and used for rotating a dielectric member incorporated into the corresponding first P/S. 
     FIG. 11 illustrates a relationship of signal transmission/reception between a block of switchable dividers and a block of first phase shifters. 
     Referring to FIG. 11, each of the divided signals from the output ports TX 11  to TX PQ  of the first block of switchable dividers  510 - 1  is inputted to a corresponding input port of the first block of first P/Ss  520 - 1 . For example, the divided signals from TX 11  to TX 1M  are inputted to RX 11  to RX 1M  of the first phase shifter  520 - 1 - 1 . 
     FIG. 12 illustrates a relationship of signal transmission/reception between a first phase shifter and its neighbor elements. 
     Referring to FIG. 12, there is shown a detailed diagram representing a relationship between the first phase shifter  520 - 1 - 1  and neighbor elements. The first phase shifter  520 - 1 - 1  includes a dielectric member (not shown), Q number of transmission lines, Q number of input ports RX 11  to RX 1Q  and Q number of output ports TX 11  to TX 1Q . As shown in this figure, it is possible to simultaneously modulate phases of the divided signals from the switchable divider  510 - 1 - 1  by rotating the dielectric member at a predetermined angle θ 1 . The electrical lengths of the transmission lines located at a half portion increase to a predetermined degree, those of the other portion decrease to the predetermined degree, simultaneously. The first P/S  520 - 1 - 1  is described in detail in U.S. patent application Ser. No. 09/798,908 filed on Mar. 6, 2001 by the same applicant, entitled: “SIGNAL PROCESS APPARATUS FOR PHASE-SHIFTING N NUMBER OF SIGNALS INPUTTED THERETO”, which is incorporated herein by reference. 
     In the preferred embodiment, each of the first P/Ss  520 - 1 - 1  to  520 - 1 -P can implement a horizontal beam steering. For example, if the horizontal motor driver  720  send a motor control signal to the first P/S  520 - 1 - 1  to rotate the dielectric member at the predetermined angle θ 1 . Half of divided signals from the switchable divider  510 - 1 - 1  are phase-shifted in advance and the other are phase-delayed after passing through the first P/S  520 - 1 - 1 . Therefore, in the row R 1  of the antenna array  130 , each of the radiators R 11  to R 1M  receives a different signal, which is linearly symmetric with respect to a center point of the row R 1 . That is, the antenna can electrically steering a beam emitted from the row R 1  in horizontal based on the rotation of the dielectric member. 
     The phase-shifted signals W 20  are transmitted to the first block of first C/Ds  530 - 1 . The detailed description is described with reference to FIG.  12 . The first phase shifters  520 - 1 - 1 ,  520 - 1 - 2  . . . and  520 - 1 -P include output ports TX 11  to TX 1Q , TX 21  to TX 2Q  and TX P1  to TX PQ , respectively. And also, the CDs  530 - 1 - 1 ,  530 - 1 - 2  and  530 - 1 -Q include input ports RX 11  to RX P1 , RX 12  to RX P2  and RX 1Q  to RX PQ , respectively. Each of the phase-shifted signals from the output ports TX 11  to TX PQ  is transmitted to a corresponding input port. For example, if a phase-shifted signal from the output port TX 12  of the first block of first P/Ss  520 - 1  is transmitted to the input port RX 12  of the first block of the C/Ds  530 - 1 . That is, an output port TX PQ  is connected to an input port RX PQ  in such a way that the sub-index of the output port TX PQ  corresponds to that of the input port RX PQ . 
     Each of the C/Ds  530 - 1 - 1  to  530 - 1 -Q transmits the phase-shifted signals W 31  to W 3 Q from the first P/Ss  520 - 1 - 1  to  520 - 1 -P to the corresponding second phase shifter, as shown in FIG.  5 . Each of the second phase shifter  540 - 1 - 1  to  540 - 1 -Q transmits the signals from the first block of first C/Ds  530 - 1 . 
     FIG. 14 illustrates a relationship of signal transmission/reception between a second phase shifter and its neighbor elements. 
     Referring to FIG. 14, there is shown a detailed diagram representing a relationship between the second phase shifter  540 - 1 - 1  and neighbor element shown. The function and the structure of the second P/S  540 - 1 - 1  is similar to those of the first P/S  520 - 1 - 1  except that the second P/S  540 - 1 - 1  has P number of transmission lines. And also, it is possible to simultaneously modulate phases of signals inputted to the input ports RX 11  to RX P1  by rotating the dielectric member at a predetermined angle θ 2 . The electrical lengths of the transmission lines located at a half portion increase to a predetermined degree, those of the other portion decrease to the predetermined degree, simultaneously. 
     Down tilting is used to decrease a cell size from a beam shape directed to the horizon to the periphery of the cell. This provides a reduction in beam coverage, yet allows a greater number of users to operate within a cell since there is a reduction in the number of interfering signals. In the preferred embodiment, this down tilting can be obtained by rotating the dielectric members incorporated into the second P/S  540 - 1 - 1  to  540 - 1 -Q for each column C 1  to C Q . Specifically, in accordance with the preferred embodiment of the present invention, the signals inputted through half of the input ports RX 11  to RX (P-1)/21  are shifted in advance and the signals inputted through the input ports RX P/21  to RX P1  are delayed in phase after passing through the output ports TX 11  to TX P1 . The amount of shifted phase has a linear symmetry with respect to the center points of each column C 1 -C Q  due to a symmetric arrangement of the second phase shifter. 
     FIG. 15 is a schematic representation of a beam from an antenna system carried out a down-tilt in accordance with the present invention. 
     Referring to FIG. 15, if the second P/S does not rotates the dielectric member, the signals outputted from the output ports TX 11  to TX 1N  are located at a phase plane PP 1 . In this case, the beam radiated from the array  130  of the radiators R 11  to R QP  has a beam pattern BP 1 . Whereas, if the second P/S rotates the dielectric member to the predetermined angle θ 2 , the signals outputted from the output ports TX 11  to TX P1  are located at a phase plane PP 2 . Therefore, the beam radiated from the array  130  of the radiators R 11  to R PQ  has a beam pattern BP 2  which is rotated α degrees from the beam pattern BP 1 . 
     FIG. 16A plots a beam pattern for electrically down tilting a beam emitted from an antenna system in accordance with the present invention. 
     Referring to FIG. 16A, there are shown antenna gain plots on polar coordinate in the horizontal plane at the level of the antenna when the antenna system  100  implements the down tilting with rotating the dielectric members of the second P/Ss  540 - 1 - 1  to  540 - 1 -Q. 
     FIG. 16B plots a beam pattern for horizontally steering a beam emitted from an antenna system in accordance with the present invention. 
     In this drawing, shown are antenna gain plots on polar coordinate in the horizontal plane when the antenna system  100  implements the horizontal beam steering with rotating the dielectric members of the first P/Ss  520 - 1 - 1  to  520 - 1 -P. 
     FIG. 16C plots a beam pattern for horizontally switching a beam width emitted from an antenna system in accordance with the present invention. 
     As shown in this drawing, plotted is an antenna gain when the antenna system  100  implements the horizontally beam width switching. In this case, the antenna array  130  is made of radiators R 11  to R 84  for applying IMT- 2000 . That is the number of columns is 4 and the number of rows is 8. The first block of first phase shifters  520 - 1  has only one first phase shifter in order to control all of the rows in the same manner. Therefore, the first block of switchable dividers  510 - 1  has one switchable divider. The switchable divider is set to operate at 4-way at a maximum operating mode. As can be shown, when the switchable divider operates at 4-way, the beam radiated from the array  130  has a HPBW (half power beam width) to be approximately 32 degrees. If the switchable divider operates at 3-way, the beam has HPBW to be approximately 45 degrees. The switchable divider operates at 2-way, the beam has HPBW to be approximately 64 degrees. 
     With reference to FIGS. 17 to  24 , antenna systems and base transceiver stations having the same antenna system which can control multi beams of input signals, and multi beam controlling method will be described. 
     FIGS. 17A and 17B show a base transceiver station (BTS) having a multi-beam controllable antenna system in accordance with the present invention. 
     The BTS includes an antenna array  1750 , up/down converters  1701 - 1  to  1701 - 4 , horizontal half-power beam width controlling switchable dividers  1703 - 1  to  1703 - 3 , horizontal tilting angle controlling phase shifters  1705 - 1  to  1705 - 3 , phase shifter drivers  1707 - 1  to  1707 - 3 , fixed combiners  1709 - 1  to  1709 - 3 , multi channel power amplifiers (MCPA)  1711 - 1  to  1711 - 4 , duplex filters  1713 - 1  to  1713 - 4 , switchable dividers  1715 - 1  to  1715 - 4 , phase shifters  1717 - 1  to  1717 - 4  for controlling the vertical tilting angles, a phase shifter  1719 , low noise amplifiers  1721 - 1  to  1721 - 4 , fixed dividers  1723 - 1  to  1723 - 3 , phase shifters  1725 - 1  to  1725 - 3 , phase shift driver  1727 - 1  to  1727 - 3 , switchable combiners  1729 - 1  to  1729 - 3  and a controller  1731 . 
     Each of he up/down converters  1701 - 1  to  1701 - 4  receives signals to be transmitted or received, and up/down converting frequencies of the signals. 
     Each of the horizontal half-power beam width controlling switchable dividers switchable dividers (S/D)  1703 - 1  to  1703 - 3  receives an up-converted signal from the up/down converter  1701 - 1  to  1701 - 4  and divides the up-converted signal into a predetermined number of divided signals. 
     Each of the phase shifters  1705 - 1  to  1705 - 3  shifts phases of the divided signals based on a first control signal from a phase shift driver  1707 - 1 ,  1707 - 2  or  1707 - 3 , so that horizontal half-power beam widths of the signal to be transmitted are controlled. 
     Each of the fixed combiners  1709 - 1  to  1709 - 3  receives and combines the divided signals from the phase shifters. 
     Each of the multi channel power amplifiers (MCPA)  1711 - 1  to  1711 - 4  amplifies the signal from the up/down converter or the fixed combiner and outputs a channel-amplified signal. 
     Each of the duplex filters  1713 - 1  to  1713 - 4  performs filtering of the channel-amplified signal from the MCPA and provides a first filtered signal to the antenna array, or performs filtering of the received signal from the antenna array and provides a second filtered signal to the low noise amplifiers. 
     Each of the switchable dividers  1715 - 1  to  1715 - 4  divides the signal outputted from the duplex filter  1713 - 1  to  1713 - 4  into eight signals in order to control vertical half-power beam width of the signal to be transmitted. 
     Each of the phase shifters  1717 - 1  to  1717 - 4  shifts phases of the signals from the switchable divider  1715 - 1  to  1715 - 4  and generates phase-shifted signals in order to control vertical tilting angle of the signal to be transmitted. 
     The phase shift driver  1719  generates a control signal to control the phase shifters simultaneously. 
     The phase-shifted signals are radiated through the antenna array  1750 . 
     Signals received by the antenna array  1750  are filtered by the duplex filters  1713 - 1  to  1713 - 4  and amplified by the low noise amplifiers  1721 - 1  to  1721 - 4 . 
     Each of the fixed dividers  1723 - 1  to  1725 - 3  divides the low noise-amplified signals into three divided signals. 
     Each of the phase shifter  1725 - 1  to  1725 - 3  shifts receives the divided signals one by one and shifts phases of the divided signal, to thereby control horizontal tilting angle of the received signal. 
     The phase shift drivers  1727 - 1  to  1727 - 3  control the phase shifters independently. 
     Each of the switchable combiner receives signals from the phase shifter and combines a signal in order to control horizontal half-power beam width. 
     The controller  1731  controls the phase shift drivers, the switchable dividers and the switchable combiners. 
     The number of sectors included in a cell or the number of the frequency assignments in a sector is designed based on terrestrial characteristics of the cell. 
     In this specification, only for easy description, let assume that the cell is divided into three sectors and four frequency assignments FA 1  to FA 4  are assigned to the sector. Also, let assume that the first frequency assignment FA 1  is a fixed FA of which the vertical tilting angle and the horizontal half-power beam width are fixed, and the second through forth frequency assignments FA 2  to FA 4  are variable FAs of which the vertical tilting angle and the horizontal half-power beam width are fixed can be varied. 
     In the embodiment, it is assume that the first to third horizontal half-power beam width control switchable dividers and the first to third horizontal half-power beam width control switchable combiners are all three-way dividers and combiners, and the fixed combiners and the fixed dividers are all three-way combiners and dividers. 
     The horizontal tilting angle phase shifters are phase shifters having three transmission lines. 
     The first to forth vertical half-power beam width control switchable dividers eight-way dividers, the first to the forth vertical tilting angle control phase shifters are phase shifters having eight transmission lines. 
     Operations and functions of the up/down converters, fixed combiners, the duplex filter, the low noise amplifier (LNA) and fixed divider are well known to one skilled in the art, and therefore, detailed description will be skipped in this specification. 
     The frequency assignment FA 1  outputted from the first up/down converter  1701 - 1  is provided to the first multi channel power amplifier (MCPA). The others, FA 2  to FA 4  outputted from the second to forth up/down converters  1701 - 2  to  1701 - 4  is divided into three signals by the horizontal half-power beam width control switchable dividers  1703 - 1  to  1703 - 3 . 
     The first to third horizontal tilting angle control phase shifters  1705 - 1  to  1705 - 3  are controlled by the first to third phase shift drivers  1707 - 1  to  1707 - 3  respectively. 
     The first to third fixed combiners  1709 - 1  to  1709 - 3  receives and combines one of the divided signals from the phase shifters  1705 - 1  to  1705 - 3 . 
     Each of the multi channel power amplifiers (MCPA)  1711 - 1  to  1711 - 3  amplifies the signal from the fixed combiner and outputs a channel-amplified signal. 
     The first duplex filter  1713 - 1  receives the signal from the first up/down converter through the first MCPA  1711 - 1 . The second to forth duplex filters  1713 - 2  to  1713 - 4  receive the signals from the second to forth MCPA  1711 - 2  to  1711 - 4 . The duplex filters  1713 - 1  to  1713 - 4  perform filtering of the signals from the MCPA  1711 - 1  to  1711 - 4  and generates filtered signals. 
     Each of the vertical half-power beam width control switchable divider  1715 - 1  to  1715 - 4  receives and divides the filtered signals into eight divided signals. 
     Each of the vertical tilting angle control phase shifters  1717 - 1  to  1717 - 4  controls phases of the divided signals at the same rate and provides the phase-controlled signals to the antenna array. 
     The vertical tilting angle control phase shifters  1717 - 1  to  1717 - 4  are simultaneously controlled by the phase shift driver  1719  at the same rate. 
     The received signals are received by the antenna array  60  and inputted to the duplex filters  1713 - 1  to  1713 - 4  through the vertical tilting angle control phase shifters  1717 - 1  to  1717 - 4  and the vertical half-power beam width control switchable dividers  1715 - 1  to  1715 - 4 . 
     The duplex filters  1713 - 1  to  1713 - 4  perform filtering of the received signal from the vertical half-power beam width control switchable dividers  1715 - 1  to  1715 - 4  and provides a second filtered signal to the low noise amplifiers  1721 - 1  to  1721 - 4 . 
     Each of the fixed dividers  1723 - 1  to  1723 - 3  divides the low noise-amplified signals into three divided signals. 
     The three divided signals from the fixed dividers  1723 - 1  to  1723 - 3  are received one by one at the horizontal tilting angle controlling phase shifters  1725 - 1  to  1725 - 3  and the phases of the divided signal are shifted. 
     The phase-shifted signals are combined by the horizontal half-power beam width controlling switchable combiners  1729 - 1  to  1729 - 3 . 
     The combined signals by the horizontal half-power beam width controlling switchable combiners  1729 - 1  to  1729 - 3  are down-converted by the up/down converters  1701 - 1  to  1701 - 4  and transmitted to the mobile switching center (MSC) (not shown) through the base station controller (BSC)(not shown). 
     Hereinafter, a procedure of controlling the horizontal half-power beam width of a corresponding frequency assignment by the horizontal half-power beam width controlling switchable divider will be in detail with reference to FIGS. 17A and 17B. 
     It is assume that In case of three-way divider being used for the horizontal half-power beam width controlling switchable divider  1703 - 1  to  1703 - 3 , the horizontal half-power beam widths of the FA 2 , FA 3  and FA 4  are 30 degrees. In case of two-way, the horizontal half-power beam widths of the FA 2 , FA 3  and FA 4  are 60 degrees, and in case of one-way, those of the FA 2 , FA 3  and FA 4  are 90 degrees. 
     The FA 1  can be used as a variable FA by connecting the horizontal half-power beam width controlling switchable divider, the horizontal tilting angle controlling phase shifter and the fixed combiners. In this case, four-way switchable divider and four transmission lines should be used, and therefore, the horizontal half-power beam width of each FA can be varied between 120 and 0 degree. 
     According to the number of ways of the divider, the horizontal half-power beam width of the FA can be varied and is not limited to a certain angle. 
     For example, if the horizontal half-power beam width controlling switchable divider  1703 - 1  is a four-way divider, the FA signals are radiated through the horizontal tilting angle controlling phase shifter  1705 - 1 , the vertical half-power beam width controlling switchable divider  1715 - 1  to  1715 - 4 , the vertical tilting angle controlling phase shifter  1717 - 1  to  1717 - 4  and the radiators  1705 - 1  to  1705 - 4  of the antenna array. In other words, the FA signals are radiated through four array antennas. 
     However, if the horizontal half-power beam width controlling switchable divider  1703 - 1  is a three-way, two-way or one-way divider, the FA signals are radiated through three, two, or one array antenna(s). 
     The variation in the number of the antenna array means that the horizontal half-power beam width of the FA signal is varied. If horizontal half-power beam width of the FA signal can be varied, local traffic increase can be solved. 
     In the horizontal tilting angle controlling phase shifter  1705 - 1 , arc transmission lines are symmetrically formed. At driving the phase shift, the phases of the transmission lines are symmetrically varied with the same rate. In other words, since the phases of the signals fed to the radiators  1750 - 1  to  1750 - 4  of the antenna array are symmetrically varied with the same rate, the FA signals can be horizontally tilted. 
     As mentioned above, if the FA signals can be horizontally tilted, an antenna beam can be radiated to a wanted area, and therefore, the antenna can be established freely and it can be dealt with a local traffic increase. 
     A method for controlling the vertical half-power beam width is similar to the method for controlling the horizontal half-power beam width as mentioned above. In other words, if the vertical half-power beam width controlling switchable divider  1715 - 1  operates as the eight-way divider, the FA signals are radiated through eight antenna arrays, if does as the seven-way to one-way divider, the FA signals are radiated through seven antenna arrays to one antenna array. 
     The variation in the number of the antenna array means that the vertical half-power beam width of the FA signal is varied. 
     At driving the vertical half-power beam width controlling phase shifter  1717 - 1 , the phases of the transmission lines are symmetrically varied with the same rate. In other words, since the phases of the signals fed to the eight antenna arrays are symmetrically varied with the same rate, the FA signals can be vertical tilted. 
     As mentioned above, if the FA signals can be vertically tilted, an identical channel interference signal from another BTS using the same frequency can be decreased. 
     At this time, only if the vertical half-power beam width controlling phase shifters  1717 - 1  to  1717 - 4  are simultaneously controlled with the same rate, an adjust vertical tilting can be performed. 
     Hereinafter, the horizontal and the vertical tilting will be described with reference to intensities of the FA 2 , FA 3  and FA 4 . 
     In case of the three-way divider, there are ten possible cases of the horizontal half-power beam width in each FA, for only easy description, one case will be described that all of the dividers operate as the three-way divider and the horizontal half-power beam width of the FA is 30 degree. 
     Referring to FIGS. 17A and 17B, if the intensities of the FA 2 , FA 3  and FA 4  inputted to the horizontal half-power beam width controlling switchable dividers  1703 - 1  to  1703 - 3  are denoted by  1 P 2 ,  1 P 3  and  1 P 4 ,  1 P 2  signal is divided into three  1 / 3 P 2  signals. 
     The  1 P 3  signal is divided into three  1 / 3 P 3  signals by the second horizontal half-power beam width controlling switchable divider  1703 - 2  and the  1 P 4  signal is divided into three  1 / 3 P 4  signals by the third horizontal half-power beam width controlling switchable divider  1703 - 3 . 
     The signals divided by the first to third horizontal half-power beam width controlling switchable dividers  1703 - 1  to  1703 - 3  are phase-shifted by the first to third horizontal tilting angle controlling phase shifters  1705 - 1  to  1705 - 3  and then applied to the first to third fixed combiners  1709 - 1  to  1709 - 3  respectively. 
     In other words,  1 / 3 P 2 ,  1 / 3 P 3  and  1 / 3 P 4  signals are inputted to the first to second fixed combiners  1709 - 1  to  1709 - 3  and combined respectively. The combined signals by the first to third fixed combiners  1709 - 1  to  1709 - 3  become  1 / 9 P 2 + 1 / 9 P 3 + 1 / 9 P 4 . 
     When the number of signals inputted to the first to third fixed combiners  1709 - 1  to  1709 - 3  is varied, in order not to vary the characteristics of the radio frequency, a first to a third matching circuits can be added. The matching circuit can be an isolator or a switch of which 50Ω resistor is grounded. 
     If the MCPA is an amplifier amplifying the signal 90 times, output signals of the first to third MCPA become  10 P 2 + 10 P 3 + 10 P 4 . 
     In more detail description, while the intensity of the amplified signal is  30 P,  10 P 2 + 10 P 3 + 10 P 4  signals are included in  30 P. In other words,  10 P 2 + 10 P 3 + 10 P 4  signals are radiated through three antenna arrays. 
     At this time, the horizontal half-power beam width of the FA 1  is 120 degree, and those of the FA 2  to FA 4  are 30 degrees. By horizontally tilting the FA 2 , FA 3  and FA 4  through the horizontal tilting angle controlling phase shifters  1705 - 1  to  1705 - 3 , if the FA 2 , FA 3  and FA 4  are arranged within the sector having 120 degrees, which is illustrated in FIG.  19 . 
     For another example, it will be described that the first horizontal half-power beam width controlling divider  1703 - 1  operates as one-way divider, the second horizontal half-power beam width controlling divider  1703 - 2  does as two-way divider and the third horizontal half-power beam width controlling divider  1703 - 3  does as three-way divider. 
     In other words, a case that the horizontal half-power beam width of the FA 2  is 90 degrees, the horizontal half-power beam width of the FA 3  is 60 degrees and the horizontal half-power beam width of the FA 4  is 30 degrees will be described. 
     The FA 2  signal amplified by the second up/down converter  11  is applied to the first fixed combiner  1709 - 1  through the first horizontal half-power beam width controlling switchable divider  1703 - 1  and the first horizontal tilting angle controlling phase shifter  1705 - 1 . 
     The FA 3  signal amplified by the third up/down converter  1701 - 3  is divided into two signals by the second horizontal half-power beam width controlling switchable divider  1703 - 2  and applied to the first and the third fixed combiners  1709 - 1  and  1709 - 3  through the second horizontal tilting angle controlling phase shifter  1705 - 2 . 
     The FA 4  signal amplified by the forth up/down converter  1701 - 4  is divided into three signals by the second horizontal half-power beam width controlling switchable divider  1703 - 3  and applied to the first to the third fixed combiners  1709 - 1  to  1709 - 3  through the third horizontal tilting angle controlling phase shifter  1705 - 3 . 
     The first fixed combiner  1709 - 1  receives  1 P 2 ,  1 / 2 P 3  and  1 / 3 P 4  signals, the second fixed combiner  24   1 / 3 P 4  and the third fixed combiner  1709 - 3   1 / 2 P 3  and  1 / 3 P 4  signals. 
     The signal combined by the first fixed combiner  1709 - 1  is  1 / 3 P 2 + 1 / 6 P 3 + 1 / 9 P 4  which is amplified by the first MCPA  1711 - 2  and then becomes  30 P 2 + 15 P 3 + 10 P 4 . 
     The signal combined by the second fixed combiner  24  is  1 / 9 P 4  which is amplified by the second MCPA  1711 - 2  and then becomes  10 P 4 . 
     The signal combined by the third fixed combiner  1709 - 3  is  1 / 6 P 3 + 1 / 9 P 4  which is amplified by the third MCPA  1711 - 3  and then becomes  15 P 3 + 10 P 4 . 
     At this time, although output power levels of the first, second and third MCPA  1711 - 2  to  1711 - 3  are different, i.e.,  55 P,  10 P,  35 P, each output power level of the FA 2 , FA 3  and FA 4  is the same as  30 P. 
     Since the output power level of the first MCPA  1711 - 1  is  55 P, in order to prevent one of the output power levels of the MCPA from being larger than a predetermined value, as shown in FIGS. 23A and 233, the signal outputted from the second horizontal half-power beam width controlling switchable divider  15  can be applied to the second and third fixed combiners  1709 - 2  and  1709 - 3 . 
     If the signal outputted from the second horizontal half-power beam width controlling switchable divider  1703 - 2  can be applied to the second and third fixed combiners  1709 - 2  and  1709 - 3 , the input signals of the first fixed combiner  1709 - 1  are  1 P 2  and  1 / 3 P 4 , those of the second fixed combiner  1709 - 2  are  1 / 2 P 3  and  1 / 3 P 4 , and those of the third fixed combiner  1709 - 3  are  1 / 2 P 3  and  1 / 3 P 4 . 
     The signal combined by the first fixed combiner  1709 - 1  is  1 / 3 P 2 + 1 / 9 P 4  which is amplified by the first MCPA  1711 - 1  and then becomes  30 P 2 + 10 P 4 . 
     The signal combined by the second fixed combiner  1709 - 2  is  1 / 6 P 2 + 1 / 9 P 4  which is amplified by the second MCPA  1711 - 3  and then becomes  15 P 2 + 10 P 4 . 
     The signal combined by the third fixed combiner  1709 - 3  is  1 / 6 P 3 + 1 / 9 P 4  which is amplified by the third MCPA  1711 - 3  and then becomes  15 P 3 + 10 P 4 . 
     In other words, the output power level of the first MCPA  1711 - 1  is  40 P, that of the second MCPA  1711 - 2  is  25 P, and that of the third MCPA  1711 - 3  is  25 P, such that capacity of the amplifier can be reduced. 
     At this time, by horizontally tilting the FA 2 , FA 3  and FA 4  through the horizontal tilting angle controlling phase shifters  1705 - 1  to  1705 - 3 , if the FA 2 , FA 3  and FA 4  are arranged within the sector having 120 degrees, which is illustrated in FIG.  21 . 
     When the traffic is temporarily increased in a certain area of the sector, by controlling the horizontal half-power beam width controlling switchable dividers  1703 - 1  to  1703 - 3  and the vertical tilting angle controlling phase shifters  1705 - 1  to  1705 - 3 , as showing in FIG. 22, the FA 2  and FA 3  can be focused to the certain area of which the traffic is increased. Therefore, the quality of the communication can be kept in that area. 
     For example, when the first to third horizontal half-power controlling switchable dividers  1703 - 1  to  1703 - 3  operate as one-way divider, if the traffic is temporarily increased in a certain area of one of three sectors, it is increased the number of ways of the horizontal half-power controlling switchable dividers  1703 - 1  to  1703 - 3  dividing the FA 2  to FA 4  signals so as to decrease the half-power beam width, and the beams of the FA 2  to FA 4  are controlled to be horizontally tilted to the certain area by controlling the horizontal tilting angle controlling phase shifters  1705 - 1  to  1705 - 3 . 
     In order to deal with a local traffic increase, the sector is divided smaller, which can increase the capacity of the call processing without dividing the sector. 
     In this specification, the switchable divider and the fixed combiner can be used as the switchable combiner and the fixed divider, only if the input and the output ports of them are changed. 
     The first to third horizontal half-power beam width controlling switchable combiners  1729 - 1  to  1729 - 3 , the forth to sixth horizontal tilting angle controlling phase shifters  1725 - 1  to  1725 - 3 , the first to third fixed dividers  1723 - 1  to  1723 - 3 , the first to third horizontal half-power beam width controlling switchable dividers  1703 - 1  to  1703 - 3 , the first to third horizontal tilting angle controlling phase shifters  1705 - 1  to  1705 - 3  and the first to third fixed combiners have the same connection. 
     Switching and phase-shifting of the first to third horizontal half-power beam width controlling switchable combiners  1729 - 1  to  1729 - 3 , the forth to sixth horizontal tilting angle controlling phase shifters  1725 - 1  to  1725 - 3 , the first to third horizontal half-power beam width controlling switchable dividers  1703 - 1  to  1703 - 3 , the first to third horizontal tilting angle controlling phase shifters  1705 - 1  to  1705 - 3  can be controlled based on the same control signal or independent control signals. 
     If the switching and phase-shifting are controlled based the same control signal, transmission and reception service areas which are covered by the vertical/horizontal half-power beam width and the tilting angle are identical. 
     On the contrary, if the switching and phase-shifting are controlled based the independent control signal, transmission and reception service areas are different from each other. 
     The switchable divider, the switchable combiner and the phase shift driver are controlled by the controller  1731  which receives necessary control data from the BSC and the MSC. 
     FIG. 24 shows the horizontal half-power beam widths of the FAs emitted from the antenna system when the horizontal half-power beam widths and the vertical tilting angles are controlled independently. 
     When the horizontal half-power beam widths and the vertical tilting angles can be varied freely, the beam patterns of the FAs can be illustrated as shown in FIG.  24 . 
     When using the multi beam controllable antenna system and the BTS having the same, the vertical/horizontal half-power beam width and tilting angle are automatically controlled based on the variation in the number of the subscribers and an amount of the traffic within the sector, to thereby decrease the identical channel interference signal from another BTS using the same frequency. The beam of the FA signal can be accurately steered, to thereby establish the antenna system easily. 
     When using the multi beam controllable antenna system, since optimal design in cell service area and division of the sectors can be performed in irregular microwave environments, the antenna system can be established on a various location, for example, the wall of the building, tower, etc. 
     Each FA can be assigned to a certain area within the sector, and therefore, the traffic increase of the local area can be appropriately dealt with, and the overlapped area between the FAs can be reduced. 
     Since the devices located in the conventional BTS are located in the antenna system, the transmission losses can be reduced. Therefore, a low capacity MCPA can be used, which it costs low, size of the BTS can reduced and limited radio resources can be effectively used. 
     While the present invention has been described with respect to the particular embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.