Patent Publication Number: US-2007115201-A1

Title: Antenna system and radio communication unit

Description:
TECHNICAL FIELD  
      The present invention relates to antenna devices utilizing azimuthal range antennas for transmitting and receiving radio signals, corresponding to each predetermined azimuthal range, and to radio communications apparatuses provided with the antenna devices.  
     BACKGROUND ART  
      A conventional antenna device, for example, an antenna device disclosed in Japanese Patent Laid-Open No. 1991-038933, is applicable to a base station for mobile communications; the antenna device consists of a first antenna and a second antenna used for space diversity.  
      Another antenna device, as disclosed, for example, in Japanese Patent Laid-Open No. 1993-063634, is applicable to a base station for mobile communications; the antenna device includes a first antenna corresponding to an entire radio range, and a second antenna capable of tilting the directivity thereof along vertical surface electrically or physically to depression angle direction.  
      In the case of these conventional antenna devices, when the number of antennas is intended to increase so as to enhance effectiveness of diversity, simply increasing the number of antennas has caused a problem in that installation space will only increase in vain.  
     DISCLOSURE OF THE INVENTION  
      An object of the invention is to provide an antenna device and a radio communications apparatus of which effectiveness of diversity can be maintained, or can be further enhanced while efficiently utilizing their installation space.  
      In one aspect of this invention, an antenna device includes azimuthal range antennas for transmitting and receiving radio signals from azimuthal ranges being a full sweep divided into three or more; the azimuthal range antennas are two or more, rowed horizontally in each of the azimuthal ranges; the antenna device is characterized in that the azimuthal range antennas are tilt-angle directivity antennas directed toward two or more tilt-angle ranges.  
      According to this invention, by horizontally disposing two or more azimuthal range antennas and, by having the azimuthal range antennas to perform tilt-angle directivity antennas directed toward two or more tilt-angle ranges; namely, by combining space diversity with directivity diversity, while efficiently utilizing their installation space, effectiveness of diversity can be further enhanced.  
      In another aspect of this invention, an antenna device includes azimuthal range antennas for transmitting and receiving radio signals from azimuthal ranges being a full sweep divided into three or more; the azimuthal range antennas are directed toward each of the azimuthal ranges; the antenna device is characterized in that: the azimuthal range antennas are tilt-angle directivity antennas directed toward two or more tilt-angle ranges; and simultaneously, comprises a common mast for unitarily supporting an azimuthal range antenna corresponding to an adjoining azimuthal range.  
      According to this invention, by directing, as tilt-angle directivity antennas, the azimuthal range antennas toward two or more tilt-angle ranges, while maintaining effectiveness of directivity diversity, a common mast unitarily supports an azimuthal range antenna individually corresponding to a mutually adjoining azimuthal range, so that their installation space can be utilized efficiently.  
      In yet another aspect of this invention, a radio communications apparatus includes: an antenna device having azimuthal range antennas for transmitting and receiving radio signals from azimuthal ranges being a full sweep divided into three or more, and the azimuthal range antennas are two or more, rowed horizontally in each of the azimuthal ranges; and a receiving device for processing the signals having received by way of the antenna device; the radio communications apparatus is characterized in that the azimuthal range antennas are tilt-angle directivity antennas directed toward two or more tilt-angle ranges.  
      According to a radio communications apparatus in the present invention, similarly to the antenna device described above, while efficiently utilizing its installation space, effectiveness of diversity can be further enhanced.  
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1  is a diagram showing a schematic configuration of a radio communications apparatus in Embodiment 1 of the present invention;  
       FIG. 2  is a plan view showing a schematic layout of an antenna device in Embodiment 1;  
       FIG. 3  is a diagram showing tilt-angle directivities of the antenna device in Embodiment 1;  
       FIG. 4  is a diagram showing a schematic configuration of a radio communications apparatus related to a comparative example 1;  
       FIG. 5  is a plan view showing a schematic layout of an antenna device related to the comparative example 1;  
       FIG. 6  is a diagram showing a schematic configuration of a radio communications apparatus in Embodiment 2 of the present invention;  
       FIG. 7  is a plan view showing a schematic layout of an antenna device in Embodiment 2;  
       FIG. 8  is a diagram showing an electrical configuration of an antenna device in Embodiment 3 of the present invention;  
       FIG. 9  is a diagram showing a schematic configuration of a radio communications apparatus in Embodiment 3;  
       FIG. 10  is a diagram showing a schematic configuration of a radio communications apparatus in Embodiment 4 of the present invention;  
       FIG. 11  is a diagram showing a schematic configuration of a radio communications apparatus in Embodiment 5 of the present invention;  
       FIG. 12  is a view showing a schematic configuration of an antenna device in Embodiment 6 of the present invention; and  
       FIG. 13  is a view showing a schematic configuration of an antenna device related to a comparative example 2. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
     Embodiment 1.  
       FIG. 1  is a diagram showing a schematic configuration of a radio communications apparatus in Embodiment 1 of the present invention. The radio communications apparatus  1 , which comprises an antenna device  10  and a receiving device  50 , for example, in a mobile communication systems, is applicable to a base station that radio-communicates with mobile communications terminals.  
      The antenna device  10  comprises upward directivity antennas  21  and  23 , downward directivity antennas  22  and  24 , and supporting masts  41  through  44 . The upward directivity antenna  21  is an antenna upwardly directed toward a tilt-angle range, and is supported by the mast  41 . The downward directivity antenna  22  is an antenna downwardly directed toward a tilt-angle range, and is supported by the mast  42 . The upward directivity antenna  23  is an antenna upwardly directed toward a tilt-angle range, and is supported by the mast  43 . The downward directivity antenna  24  is an antenna downwardly directed toward a tilt-angle range, and is supported by the mast  44 .  
      In these antennas, the upward directivity antenna  21  is paired with the downward directivity antenna  22 , and form a sector antenna for receiving radio signals in an azimuthal range (hereinafter referred to as “a sector”), in which the whole azimuthal angle covering the perimeter of the radio communications apparatus has been equally divided into three. Similarly, the upward directivity antenna  23  is paired with the downward directivity antenna  24 , and form a sector antenna. In  FIG. 1 , a schematic configuration corresponding only to a single sector is illustrated. The upward directivity antennas  21  and  23  are antennas (upwardly) directed toward the same tilt-angle range; in order to obtain effectiveness of space diversity, they are disposed apart from each other in horizontal directions, by a distance L 0  in accordance with radio frequencies. Similarly, the downward directivity antennas  22  and  24  are antennas (downwardly) directed toward the same tilt-angle range; in order to obtain effectiveness of space diversity, they are disposed apart from each other in horizontal directions, by a distance L 0  in accordance with radio frequencies. The distance L 0  in accordance with mutual radio frequencies is, to be specific, a distance larger than the wavelengths of radio carrier waves.  
      On the other hand, because the upward directivity antenna  21  and the downward directivity antenna  22  can unitarily obtain effectiveness of directivity diversity, these antennas can be disposed in a proximal distance (a distance L 1 ). Similarly, because the upward directivity antenna  23  and the downward directivity antenna  24  can unitarily obtain effectiveness of directivity diversity, these antennas can also be disposed in a proximal distance (a distance L 1 ). As described above, by combining the space diversity with the directivity diversity, effectiveness of diversity can be enhanced while efficiently utilizing the installation space.  
      The receiving device  50  comprises radio receivers (RX)  51  through  54 , and a selection-synthesis receiving unit  55 . The radio receiver  51  converts high-frequency signals received by the upward directivity antenna  21 , into baseband signals. Similarly, the radio receivers  52  through  54  convert high-frequency signals received by the directivity antennas  22  through  24 , into baseband signals, respectively. Based on the signals having obtained by way of each of the directivity antennas  21  through  24 , the selection-synthesis receiving unit  55  determines receiving signals by performing selection or synthesis processing.  
      The selection or synthesis processing performed by the selection-synthesis receiving unit  55  has the following types with respect to each of the space diversity and the directivity diversity.  
      To begin with, in the case of the pair of upward directivity antennas  21  and  23  that performs space diversity, there exist a selection type that selects either of the signals having good receiving quality, and a synthesis type that synthesizes two signals. The former has an advantage of removing influence caused by the signals having poor receiving quality; the latter has an advantage of compensating one signal with the other signal when a receiving level is locally lowered by such as fading. Similarly, in the case of the pair of downward directivity antennas  22  and  24  that performs space diversity, there exist a selection type and a synthesis type, and the advantages are also similar. Moreover, a selection-synthesis type that selects either the selection type or the synthesis type is also applicable. The selection-synthesis type has both the advantages the selection type and the synthesis tape have.  
      In the cases of the pair of upward directivity antenna  21  and downward directivity antenna  22  that performs directivity diversity, and the pair of upward directivity antenna  23  and downward directivity antenna  24 , there exist a selection type that selects either of the signals with good receiving quality, and a synthesis type that synthesizes two signals. The selection type has an advantage of removing influence caused by the signals with poor receiving quality. To be more specific in explanation, when a communications party is present at an outer area in the communicable area covered by the radio communications apparatus  1 , signals with higher gain from the upward directivity antenna can be selected, and signals with low gain and picked-up noise from the downward directivity antenna can be removed. On the contrary, when the communications party is present within an inner area of the communicable area, signals with higher gain from the downward directivity antenna can be selected, and signals with low gain and picked-up noise from the upward directivity antenna can be removed. When the communications party is present near the boundary between the outer area and the inner area of the communicable area, the synthesis type synthesizes both the signal with lowered gain from the upward directivity antenna and the signal with lowered gain from the downward directivity antenna, so as to compensate with each other; thus signals with high gain can be received. Moreover, similarly to the case of space diversity, the selection-synthesis type is also applicable.  
       FIG. 2  is a plan view showing a schematic layout of the antenna device in Embodiment 1. In addition to the upward directivity antennas  21  and  23 , the downward directivity antennas  22  and  24 , and the masts  41  through  44 , explained referring to  FIG. 1 , the antenna device  10  comprises upward directivity antennas  25 ,  27 ,  29  and  31 , downward directivity antennas  26 ,  28 ,  30  and  32 , and masts  45  through  49 . Among these items, the upward directivity antenna  21  and the downward directivity antenna  22  illustrated in  FIG. 1  compose a first sector antennas  11 , and the upward directivity antenna  23  and the downward directivity antenna  24  compose a first sector antennas  12 . Similarly, the upward directivity antenna  25  and the downward directivity antenna  26  compose a second sector antennas  13 , and the upward directivity antenna  27  and the downward directivity antenna  28  compose a second sector antennas  14 . Similarly again, the upward directivity antenna  29  and the downward directivity antenna  30  compose a third sector antennas  15 , and the upward directivity antenna  31  and the downward directivity antenna  32  compose a third sector antennas  16 .  
      As illustrated in  FIG. 1 , the mast  44  supports the downward directivity antenna  24 , as well as the upward directivity antenna  25 . The mast  45  supports the downward directivity antenna  26 . The mast  46  supports the upward directivity antenna  27 . The mast  47  supports not only the downward directivity antenna  28 , but also the upward directivity antenna  29 . The mast  48  supports the downward directivity antenna  30 . The mast  49  supports the upward directivity antenna  31 . As illustrated in  FIG. 1 , the mast  41  supports the upward directivity antenna  21 , as well as the downward directivity antenna  32 .  
      The first sector antennas  11  and  12 , the second sector antennas  13  and  14 , and the third sector antennas  15  and  16 , are disposed in such a way that each pair draws each side of a triangle. Accordingly, the masts  41  through  49  are disposed to draw a triangle; in particular, the masts  41 ,  44  and  47  that commonly support two directivity antennas, are disposed at each vertex of the triangle drawn by the masts  41  through  49 .  
      With reference to  FIG. 1 , it has been described that, while separately disposing the first sector antennas  11  and  12  apart, the upward directivity antenna  21  and the downward directivity antenna  22  can be disposed in a proximal distance, and the upward directivity antenna  23  and the downward directivity antenna  24  can be disposed in a proximal distance, which is the same as the case with the antennas corresponding to the second sector antennas and the third sector antennas, respectively. Therefore, as shown in  FIG. 2 , the antenna device  10  can be installed by only allocating adequate spaces at three locations, so that space-utilizing efficiency can be increased.  
      Moreover, because the masts  41 ,  44  and  47  are commonly used in each sector adjoining to each other, from an aspect of installation of the antenna device  10 , space-utilizing efficiency can be further increased.  
      Furthermore, with reference to  FIG. 2 , although a configuration of the antenna device  10  corresponding to all the sectors has been described, the configuration of the receiving device  50  shown in  FIG. 1  only corresponds to the first sector, and an actual receiving device  50 , similarly corresponding to the second sector and the third sector, has a configuration similar to that of  FIG. 1 ; namely, the configuration includes radio receivers and a selection-synthesis receiving unit.  
      Still furthermore, with reference to  FIG. 1  and  FIG. 2 , corresponding to the three sectors, the antenna device and the radio communications apparatus are shown having two pairs of sector antennas in each sector, and directed toward two pairs of tilt-angle ranges; however, these are not the only cases, so that, corresponding to four or more than four sectors, expansion is possible in configurations having three or more than three pairs of sector antennas in each sector, and directed toward three or more than three pairs of tilt-angle ranges.  
       FIG. 3  is a diagram showing tilt-angle directivities of the antenna device in Embodiment 1. The tilt angle is an angle in the vertical plane including the antenna device  10  with respect to the horizontal directions. A curve  61  shows an antenna gain in relation to the tilt angle of the upward directivity antenna. A curve  62  shows an antenna gain in relation to the tilt angle of the downward directivity antenna. A curve  63  shows an antenna gain of the antenna covering both the upward and downward tilt-angle ranges.  
      The curve  61  forms an elliptical shape having a specific center axis (the major axis  61   a ). Therefore, the antenna gain obtained by the upward directivity antenna demonstrates a directivity within a narrow tilt-angle range centered on the major axis  61   a  including the tilt angle. Similarly, the curve  62  forms an elliptical shape having a specific center axis (the major axis  62   a ). Therefore, the antenna gain obtained by the downward directivity antenna demonstrates a directivity within a narrow tilt-angle range centered on the major axis  62   a  including the tilt angle. The tilt angle of the major axis  61   a  is smaller than that of the major axis  62   a , and is close to be horizontal. Based on these tilt-angle directivities, the radio communications apparatus  1  can radio-communicate with a distant communications party by mainly using the upward directivity antennas, and with a near communications party by mainly using the downward directivity antennas.  
       FIG. 4  is a diagram showing a schematic configuration of a radio communications apparatus related to a comparative example 1. The radio communications apparatus  101 , in comparison with the radio communications apparatus  1  shown in  FIG. 1 , replaces the antenna device  10  with an antenna device  110 . As far as other configurations are concerned, the same reference numerals and symbols are designated and their explanation is thus omitted, and a configuration of the antenna device  110  is described. The antenna device  110  includes a first sector antennas  111  through  114 , and masts  41  through  44 . The first sector antennas  111  through  114  do not in particular have tilt-angle directivities, but are disposed at predetermined intervals based on each radio frequencies.  
       FIG. 5  is a plan view showing a schematic layout of the antenna device related to the comparative example 1. In addition to the first sector antennas  111  through  114 , and the masts  41  through  44 , as illustrated in  FIG. 4 , the antenna device  110  includes second sector antennas  115  through  118 , third sector antennas  119  through  122 , and masts  45  through  49 .  
      When the above-described radio communications apparatus  101  related to the comparative example 1 is compared with the radio communications apparatus  1  in Embodiment 1, the comparative example 1 only performs space diversity by simply disposing four sector antennas for each individual sector, meanwhile, Embodiment 1 combines space diversity with directivity diversity together for each individual sector; therefore installation-space utilizing efficiency is high.  
     Embodiment 2.  
       FIG. 6  is a diagram showing a schematic configuration of a radio communications apparatus in Embodiment 2 of the present invention. The radio communications apparatus  2 , in the radio communications apparatus  1  shown in  FIG. 1 , replaces the antenna device  10  with an antenna device  70 . In the case of the antenna device  70 , a common mast  77  supports both the upward directivity antenna  21  and the downward directivity antenna  22 , which are individually supported by each mast in the antenna device  10 ; and similarly, a common mast  78  supports both the upward directivity antenna  23  and the downward directivity antenna  24 . On the mast  77 , the upward directivity antenna  21  is disposed above the downward directivity antenna  22 , and on the mast  78 , the upward directivity antenna  23  is disposed above the downward directivity antenna  24 , respectively. Because other configurations are the same as those of the radio communications apparatus  1  shown in  FIG. 1 , the same reference numerals and symbols are designated, and their explanation is thus omitted.  
      As described above, when an antenna device is installed by supporting both the upward directivity antenna and downward directivity antenna on a common mast, space-utilizing efficiency can be further increased.  
       FIG. 7  is a plan view showing a schematic layout of the antenna device in Embodiment 2. In addition to the upward directivity antennas  21  and  23 , the downward directivity antennas  22  and  24 , and the masts  77  and  78 , explained referring to  FIG. 6 , the antenna device  70  comprises upward directivity antennas  25 ,  27 ,  29  and  31 , downward directivity antennas  26 ,  28 ,  30  and  32 , and a mast  79 . Among those, as explained in  FIG. 6 , the upward directivity antenna  21  and the downward directivity antenna  22  compose a first sector antennas  71 , and the upward directivity antenna  23  and the downward directivity antenna  24  compose a first sector antennas  72 . Similarly, the upward directivity antenna  25  and the downward directivity antenna  26  compose a second sector antennas  73 , and the upward directivity antenna  27  and the downward directivity antenna  28  compose a second sector antennas  74 . Similarly again, the upward directivity antenna  29  and the downward directivity antenna  30  compose a third sector antennas  75 , and the upward directivity antenna  31  and the downward directivity antenna  32  compose a third sector antennas  76 .  
      As explained in  FIG. 6 , the mast  78  supports the first sector antennas  72 , as well as the second sector antennas  73 . The mast  79  supports the second sector antennas  74 , as well as the third sector antennas  75 . As explained in  FIG. 6 , the mast  77  supports the first sector antennas  71 , as well as the third sector antennas  76 .  
      The first sector antennas  71  and  72 , the second sector antennas  73  and  74 , and the third sector antennas  75  and  76 , are disposed in such a way that each pair draws each side of a triangle. In accordance with the above, the masts  77  through  79  are disposed at each vertex of the triangle.  
      As described above, by supporting sector antennas corresponding to each sector, together with sector antennas corresponding to adjoining sectors, on a common mast, as well as by supporting upward directivity antennas and downward directivity antennas on the common mast, an antenna device can be installed by using only three masts, so that space-utilizing efficiency can be further increased.  
     Embodiment 3.  
       FIG. 8  is a diagram showing an electrical configuration of an antenna device in Embodiment 3 of the present invention. The antenna device  80  unifies, as a common single first-sector antenna  81 , the upward directivity antenna  21  and the downward directivity antenna  22  that are individually used in the antenna device  70  shown in  FIG. 6 . The antenna device  80  comprises the first sector antenna  81 , dividers  85  through  88 , phase correctors  89  through  92 , and output connectors  93  and  94 . The first sector antenna  81  includes antenna elements  95  through  98  that are disposed in vertical directions, and are individually capable of receiving radio signals. Each of the dividers  85  through  88  distributes the signals from the antenna elements  95  through  98  into two signals of the same, respectively. One of the signal lines being outputted from each of the dividers  85  through  88  is connected to the output connector  93  without passing through the phase correctors. The other of the signal lines being outputted from each of the dividers  85  through  88  is connected to the output connector  94  by way of the phase correctors  89  through  92 , respectively.  
      As described above, because, on one hand, each signal from the antenna elements  95  through  98  is synthesized maintaining the same phase without phase correction and is outputted from the connector  93 , and on the other hand, each signal from the antenna elements  95  through  98  is synthesized with the phase shifted after the phase having been corrected, and is outputted from the connector  94 , by using the single directivity antenna  81 , receiving signals directed toward two tilt-angle ranges can be outputted. By using these characteristics, the same tilt-angle directivities shown in  FIG. 3  can be achieved.  
       FIG. 9  is a diagram showing a schematic configuration of a radio communications apparatus in Embodiment 3. The radio communications apparatus  3 , in the radio communications apparatus  2  shown in  FIG. 6 , replaces the antenna device  70  with the antenna device  80 . In  FIG. 8 , the configuration is graphically shown by referring to the first sector antenna  81  alone; however, in an actual case, the antenna device  80  also comprises another first-sector antenna  82  corresponding to the first sector antenna. Moreover, two sector antennas are individually provided for the second sector and the third sector each.  
      By taking these configurations, upward directivity antennas and downward directivity antennas can be integrated together for each of the sector antennas; thus, installation space for the antennas can be reduced.  
     Embodiment 4.  
       FIG. 10  is a diagram showing a schematic configuration of a radio communications apparatus in Embodiment 4 of the present invention. A radio communications apparatus  4  is configured by adding a transmitting device  200  and duplexers  211  through  214  to the radio communications apparatus  1  shown in  FIG. 1 . For the same configurations as in the radio communications apparatus  1 , the same reference numerals and symbols are designated and their explanation is omitted; thus, explanations are given as below to other configurations that differ from those of the radio communications apparatus  1 .  
      The transmitting device  200  comprises a selecting-transmitting unit  201 , radio transmitters (TX)  202  and  203 , and dividers  204  and  205 . Following an instruction given from the selection-synthesis receiving unit  55  in the receiving device  50 , the selecting-transmitting unit  201  selects either upward or downward, or both tilt-angle directivities; baseband transmitting signals are outputted to the radio transmitter  202  or the radio transmitter  203  corresponding to the tilt-angle directivity. Both the radio transmitters  202  and  203  convert the baseband transmitting signals given from the selecting-transmitting unit  201  into high-frequency-band signals capable of radio transmission. On one hand, the radio transmitter  202 , which is connected to the upward directivity antenna  21  by way of the divider  204  and the duplexer  211 , and is also connected to the upward directivity antenna  23  by way of the divider  204  and the duplexer  213 , therefore, corresponds to upward directivity. On the other hand, the radio transmitter  203 , which is connected to the downward directivity antenna  22  by way of the divider  205  and the duplexer  212 , and is also connected to the downward directivity antenna  24  by way of the divider  205  and the duplexer  214 , therefore, corresponds to downward directivity. The divider  204  distributes the high-frequency signals having been outputted from the radio transmitter  202  to the upward directivity antenna  21  and the upward directivity antenna  23 . The divider  205  distributes the high-frequency signals having been outputted from the radio transmitter  203  to the upward directivity antenna  22  and the upward directivity antenna  24 .  
      The duplexer  211  is disposed on a signal line connecting the upward directivity antenna  21  with the radio receiver  51 , and connects the radio receiver  51  with the divider  204 , as well. The duplexer  212  is disposed on a signal line connecting the downward directivity antenna  22  with the radio receiver  52 , and connects the radio receiver  52  with the divider  205 , as well. The duplexer  213  is disposed on a signal line connecting the upward directivity antenna  23  with the radio receiver  53 , and connects the radio receiver  53  with the divider  204 , as well. The duplexer  214  is disposed on a signal line connecting the downward directivity antenna  24  with the radio receiver  54 , and connects the radio receiver  54  with the divider  205 , as well.  
      In addition to the above, based on the receiving signals, the selection-synthesis receiving unit  55  selects either the upward or the downward, or both the tilt-angle directivities; and simultaneously with this, in order to select either the upward or the downward, or both the tilt-angle directivities with respect to the transmitting signals, the unit  55  gives instructions of the selection to the selecting-transmitting unit  201  in the transmitting device  200 .  
      In the next place, a transmitting operation of the radio communications apparatus  4  is described.  
      When transmitting signals are generated to transmit to a communications party in the radio communications apparatus  4 , the transmitting signals will be outputted by the selecting-transmitting unit  201 , either to the radio transmitter  202  or to the radio transmitter  203 , or to both. To which way the signals are outputted follows an instruction given from the selection-synthesis receiving unit  55 .  
      That is to say, when the selection-synthesis receiving unit  55  selects the upward directivity based on the receiving signals, in terms of the transmitting signals, an instruction signal for selecting the upward directivity is transmitted from the selection-synthesis receiving unit  55  to the selecting-transmitting unit  201 , so that, following this instruction signal, the selecting-transmitting unit  201  selects the upward directivity. In this case, the transmitting signals will be outputted from the selecting-transmitting unit  201  to the radio transmitter  202 . The transmitting signals from the selecting-transmitting unit  201  undergo frequency-conversion in the radio transmitter  202 . The transmitting signals from the radio transmitter  202  are distributed by the divider  204 , to the upward directivity antenna  21  and the upward directivity antenna  23 . The above-distributed transmitting signals are radio-transmitted from the upward directivity antenna  21  by way of the duplexer  211 , and from the upward directivity antenna  23  by way of the duplexer  213 , respectively. The radio-transmitted signals are synthesized in midair, and are transmitted to a communications party.  
      Similarly to the above, when the selection-synthesis receiving unit  55  selects the downward directivity based on the receiving signals, also in terms of the transmitting signals, an instruction signal for selecting the downward directivity is transmitted from the selection-synthesis receiving unit  55  to the selecting-transmitting unit  201 , so that, following this instruction signal, the selecting-transmitting unit  201  selects the downward directivity. In this case, the transmitting signals will be outputted from the selecting-transmitting unit  201  to the radio transmitter  203 . The transmitting signals from the selecting-transmitting unit  201  undergo frequency-conversion in the radio transmitter  203 . The transmitting signals from radio transmitter  203  are distributed by the divider  205 , to the downward directivity antenna  22  and the downward directivity antenna  24 . The above-distributed transmitting signals are radio-transmitted from the downward directivity antenna  22  by way of the duplexer  212 , and from the downward directivity antenna  24  by way of the duplexer  214 , respectively. The radio-transmitted signals are synthesized in midair, and are transmitted to a communications party.  
      Moreover, based on the receiving signals, when the selection-synthesis receiving unit  55  selects the upward and downward directivities, both signals from the two systems, that is, the upward directivity and the downward directivity described above are radio-transmitted together.  
      In this way, based on the receiving signals, by applying the tilt-angle directivities also to the transmitting signals to the same communications party that has originated the receiving signals, radio signals can be efficiently transmitted to the communications party.  
     Embodiment 5.  
       FIG. 11  is a diagram showing a schematic configuration of a radio communications apparatus in Embodiment 5 of the present invention. The radio communications apparatus  5 , in the radio communications apparatus  4  shown in  FIG. 10 , replaces the transmitting device  200  with a transmitting device  300 . For the same configurations in the radio communications apparatus  4 , the same reference numerals and symbols are designated and their explanation is omitted; thus, explanations are given as below to other configurations that differ from those of the radio communications apparatus  4 .  
      The transmitting device  300  comprises an STTD (space-time block-coding transmit-diversity) coding unit  301 , selecting-transmitting units  302  and  303 , and radio transmitters (TX)  304  through  307 . The STTD coding unit  301  simultaneously generates one transmitting signal and the other transmitting signal that undergoes time-sequence alteration, positive-negative polarities inversion, and complex conjugating with respect to the one transmitting signal; the one is outputted to the selecting-transmitting unit  302 , and the other to the selecting-transmitting unit  303 . By this way, space diversity has been combined with time diversity, thus space-time diversity can be realized.  
      Following an instruction given from the selection-synthesis receiving unit  55  in the receiving device  50 , the selecting-transmitting unit  302  selects either upward or downward, or both tilt-angle directivities; baseband transmitting signals are outputted to the radio transmitter  304  or the radio transmitter  305  corresponding to the selected tilt-angle directivity. Following an instruction given from the selection-synthesis receiving unit  55  in the receiving device  50 , the selecting-transmitting unit  303  selects either upward or downward, or both tilt-angle directivities; baseband transmitting signals are outputted to the radio transmitter  306 , or to the radio transmitter  307 , or to the both corresponding to the selected tilt-angle directivity or directivities. In this way, in vertical directions, radio signals directed toward either or both of two tilt-angle ranges can be selectively transmitted.  
      Both the radio transmitters  304  and  305  convert the baseband transmitting signals given from the selecting-transmitting unit  302  into high-frequency-band signals capable of radio transmission. Similarly, both the radio transmitters  306  and  307  convert the baseband transmitting signals given from the selecting-transmitting unit  303  into high-frequency-band signals capable of radio transmission. The radio transmitter  304 , which is connected to the upward directivity antenna  21  by way of the duplexer  211 , corresponds to upward directivity. The radio transmitter  305 , which is connected to the downward directivity antenna  22  by way of the duplexer  212 , corresponds to downward directivity. The radio transmitter  306 , which is connected to the upward directivity antenna  23  by way of the duplexer  213 , corresponds to the upward directivity. The radio transmitter  307 , which is connected to the downward directivity antenna  24  by way of the duplexer  214 , corresponds to the downward directivity.  
      In addition to the above, based on the receiving signals, the selection-synthesis receiving unit  55  selects either the upward or the downward, or both the tilt-angle directivities; and simultaneously with this, in order to make a selection of either the upward or the downward, or both the tilt-angle directivities with respect to the transmitting signals, the unit  55  gives instructions of the selection to the selecting-transmitting units  302  and  303  in the transmitting device  300 . Furthermore, when a plurality of the receiving signals is divided over the upward directivity and the downward directivity, a priorly selected tilt-angle directivity will be selected.  
      In the next place, a transmitting operation of the radio communications apparatus  5  is described.  
      When transmitting signals are generated to transmit to a communications party in the radio communications apparatus  5 , based on the transmitting signals, two transmitting signals will be generated by the STTD coding unit  301 . One of the two transmitting signals is outputted to the selecting-transmitting unit  302 , and the other to the selecting-transmitting unit  303 . The signal having been outputted to the selecting-transmitting unit  302  is outputted by the selecting-transmitting unit  302 , to the radio transmitter  304 , or to the radio transmitter  305 , or to the both. To which way the signal is outputted follows an instruction given from the selection-synthesis receiving unit  55 .  
      That is to say, when the selection-synthesis receiving unit  55  selects the upward directivity based on the receiving signals, in terms of the transmitting signals, an instruction signal to select the upward directivity is transmitted from the selection-synthesis receiving unit  55  to the selecting-transmitting unit  302 , so that, following the instruction signal, the selecting-transmitting unit  302  selects the upward directivity. In this case, the transmitting signals will be outputted from the selecting-transmitting unit  302  to the radio transmitter  304 . The transmitting signals from the selecting-transmitting unit  302  undergo frequency-conversion in the radio transmitter  304 . The transmitting signals being outputted from the radio transmitter  304  are radio-transmitted from the upward directivity antenna  21 , by way of the duplexer  211 .  
      The other signal having been outputted to the selecting-transmitting unit  303  from the STTD coding unit is outputted by the selecting-transmitting unit  303 , to the radio transmitter  306 , or to the radio transmitter  307 , or to both. Similarly to the case in the selecting-transmitting unit  302 , to which way the other signal is outputted follows an instruction given from the selection-synthesis receiving unit  55 .  
      Namely, when the selecting-transmitting unit  302  selects the upward directivity, similarly to say, the selecting-transmitting unit  303  also selects the upward directivity. In this case, the transmitting signals will be outputted from the selecting-transmitting unit  303  to the radio transmitter  306 . The transmitting signals from the selecting-transmitting unit  303  undergo frequency-conversion in the radio transmitter  306 . The transmitting signals being outputted from the radio transmitter  306  are radio-transmitted from the upward directivity antenna  23 , by way of the duplexer  213 .  
      Similarly to say, when the selection-synthesis receiving unit  55  selects downward directivity based on the receiving signals, also in terms of the transmitting signals, an instruction signal to select the downward directivity is transmitted from the selection-synthesis receiving unit  55  to the selecting-transmitting units  302  and  303 , so that, following the instruction signal, the selecting-transmitting units  302  and  303  select the downward directivity. In this case, on one hand, the transmitting signals are outputted from the selecting-transmitting unit  302  to the radio transmitter  305 , and, on the other hand, the transmitting signals are outputted from the selecting-transmitting unit  303  to the radio transmitter  307 . The transmitting signals from the selecting-transmitting unit  302  undergo frequency-conversion in the radio transmitter  305 , and the transmitting signals from the selecting-transmitting unit  303  undergo frequency-conversion in the radio transmitter  307 . The transmitting signals being outputted from the radio transmitter  305  are radio-transmitted from the downward directivity antenna  22 , by way of the duplexer  212 . The transmitting signals being outputted from the radio transmitter  307  are radio-transmitted from the downward directivity antenna  24 , by way of the duplexer  214 .  
      Moreover, based on the receiving signals, when the selection-synthesis receiving unit  55  selects the upward and downward directivities, both signals from the two systems, that is, the upward directivity and the downward directivity described above are radio-transmitted.  
      In this way, based on the receiving signals, by applying the tilt-angle directivities also to the space-time transmit-diversity signals to the same communications party that has originated the receiving signals, radio signals can be efficiently transmitted to the communications party.  
     Embodiment 6.  
       FIG. 12  is a view showing a schematic configuration of an antenna device in Embodiment 6 of the present invention. The antenna device  400 , in the antenna device  70  shown in  FIG. 7 , replaces the two pairs of sector antennas allocated for each sector, with one pair of sector antennas for each sector.  
      The antenna device  400  comprises first sector antennas  401 , second sector antennas  402 , third sector antennas  403 , and a mast  421 . The first sector antennas  401  are configured with an upward directivity antenna  411  and a downward directivity antenna  412 . The second sector antennas  402  are configured with an upward directivity antenna  413  and a downward directivity antenna  414 . The third sector antennas  403  are configured with an upward directivity antenna  415  and a downward directivity antenna  416 . The mast  421  commonly supports all of the upward directivity antennas  411 ,  413  and  415 , and the downward directivity antennas  412 ,  414  and  416 .  
      In this way, by supporting the first through third sector antennas corresponding to each sector on the common mast, as well as by supporting an upward directivity antenna and a downward directivity antenna being included in each sector antennas on the common mast, the single mast  421  supports all of the directivity antennas, so that installation space for the antenna device can be utilized efficiently.  
      Moreover, combining the antenna device  400  with the receiving devices in Embodiment 1 through 5, or with further the transmitting devices thereof, can configure a radio communications apparatus. In this case, although two pairs of sector antennas are provided for each sector in Embodiment 1 through 5, the antenna device  400  is provided with only one pair of sector antennas for each sector; thereby, configurations of the receiving device and the transmitting device can be simplified by that much.  
       FIG. 13  is a view showing a schematic configuration of an antenna device related to a comparative example 2. The antenna device  500 , in the antenna device  110  shown in  FIG. 5 , replaces the four sector antennas provided for each sector with two sector antennas for each sector.  
      The antenna device  500  includes first sector antennas  501  and  502 , second sector antennas  503  and  504 , third sector antennas  505  and  506 , and masts  511 ,  512  and  513 . The mast  511  commonly supports the first sector antenna  501  and the third sector antenna  506 . The mast  512  commonly supports the first sector antenna  502  and the second sector antenna  503 . The mast  513  commonly supports the second sector antenna  504  and the third sector antenna  505 .  
      When the above-described antenna device  500  related to the comparative example 2 is compared with the antenna device  400  in Embodiment 6, that of the comparative example 2 performs space diversity by horizontally disposing two sector antennas for each individual sector; meanwhile, that of Embodiment 6 performs directivity diversity for each individual sector, therefore, installation-space utilizing efficiency is high in Embodiment 6.