Abstract:
An angle diversity receiving device performs angle diversity reception by configuring branches of angle diversity in accordance with received signals of an array antenna, the angle diversity receiving device being provided with:
   a plurality of phased array synthesizing unit that generates a received signal of a branch by performing phased array synthesis for the received signals of a plurality of antenna elements included in the array antenna; and   a correlation control unit that outputs a correlation value for the received signals of two branches;
 
wherein the phased array synthesizing unit controls the angular difference in the orientations of the branches for which the correlation value was computed so that the correlation value decreases.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to an angle diversity receiving device and an angle diversity receiving method. 
       BACKGROUND ART 
       [0002]      FIG. 7  is a block diagram illustrating a configuration of an angle diversity receiving device  600  related to the invention. Referring to  FIG. 7 , the angle diversity receiving device  600  includes a group of antennas  611  composed of two horn antennas  61 A and  61 B. The angle diversity receiving device  600  receives a received signal from the horn antenna  61 A through a band pass filter (BPF)  221 , a low noise amplifier (LNA)  231 , a received frequency converter (down converter, D/C)  241 , an automatic gain controller (AGC)  251 , and an adaptive matched filter (AMF)  131 . 
         [0003]    Further, the angle diversity receiving device  600  receives a received signal from the horn antenna  61 B through a band pass filter  222 , a low noise amplifier  232 , a received frequency converter  242 , an automatic gain controller  252 , and an adaptive matched filter  132 . In this way, the angle diversity receiving device  600  receives the received signals from the horn antennas  61 A and  61 B, as two branches (receiving system) in which angle diversity is performed. 
         [0004]    The band pass filters (BPF)  221  and  222  allow only signals within a frequency band required for reception to pass. The low noise amplifiers (LNA)  231  and  232  amplify the received signals. The received frequency converters (down converter, D/C)  241  and  242  frequency-convert the received signals. The automatic gain controllers (AGC)  251  and  252  amplify the received signals so as to suppress amplitude change of the received signals outputted to following steps. The adaptive matched filters  131  and  132  decrease unnecessary signals included in the received signal of each branch. 
         [0005]    Incidentally, diversity synthesizing circuit  140  performs diversity combining of signals inputted from the adaptive matched filters  131  and  132 . An automatic equalization circuit (decision feedback equalizer, DFE)  150  performs automatic equalization on the signals performed the diversity combining and reproduces the received signals. 
         [0006]    Such kinds of angle diversity receiving devices are disclosed for example in PTLs (Patent Literatures) 1 to 6 and NPL (Non Patent Literature) 1, except than above described one. 
         [0007]      FIG. 8  is a diagram explaining tropospheric scatter propagation. A receiving antenna  812  corresponds to, for example, the group of antennas  611  of the angle diversity receiving device  600  shown in  FIG. 7 . A radio wave transmitted from a transmitting station  811  is scattered at a first scattering point STa and a second scattering point STb, and received, as signals of orientations DTa and DTb, by the group of antennas  812 . 
         [0008]      FIG. 9  is a diagram explaining operations of the angle diversity receiving device  600  based on a related technology. The angle diversity receiving device  600  shown in  FIG. 7  and  FIG. 9  operates as follows. As shown in  FIG. 9 , two beams of antenna DR 6   a  and DR 6   b  are fixed at predetermined angles. Then, the group of antennas  611  performs angle diversity processing on received signals arriving from the dual beams of DR 6   a  and DR 6   b.    
         [0009]    The angle diversity receiving device  600  receives an arriving radio wave in a transmitting direction DTa of  FIG. 8  based on the beam of DR 6   a  in  FIG. 9 , and receives an arriving radio wave in a transmitting direction DTb of  FIG. 8  based on the beam of DR 6   b.  Here, if a condition of tropospheric scatter changes and a spatial position of the scattering points STa or STb changes, the transmitting direction DTa or the transmitting direction DTb changes. As a result, intensity of the received signals in the angle diversity receiving device  600  may remarkably decrease. 
         [0010]    That is, in the angle diversity system in which a direction of the horn antenna is fixed, when an azimuth of an arriving radio wave changes as a result of propagation condition changes, a reception level may be reduced. Particularly, in tropospheric scatter propagation, a condition of scatter propagation in troposphere widely changes due to climate change. Consequently, in the angle diversity system in which the orientations of the antennas are fixed, long-period fading with propagation loss of 10 dB to 20-odd dB occurs throughout one year, and a reception level of the radio wave may decrease. 
         [0011]    Additionally, in the angle diversity receiving device, an angle between a plurality of receiving horns is preliminarily arranged so that a correlation value between branches does not increase. In the angle diversity receiving device, a correlation value between the branches may increase as a condition of troposphere scatter changes and a diversity effect may decrease. 
       CITATION LIST 
     Patent Literature 
       [0012]    [PTL 1] Japanese Patent Publication No. 2982504 
         [0013]    [PTL 2] U.S. Pat. No. 7,623,084 B2 
         [0014]    [PTL 3] Japanese unexamined patent publication No. 06-029890 
         [0015]    [PTL 4] Japanese unexamined patent publication No. 05-344029 
         [0016]    [PTL 5] Japanese unexamined patent publication No. 04-227132 
         [0017]    [PTL 6] Japanese examined patent publication No. 07-050868 
       Non Patent Literature 
       [0018]    [NPL 1] ‘Performance of an Experimental Angle-Diversity Troposcatter System’ (P. Monsen, IEEE TRANSACTIONS ON COMMUNICATIONS, April 1972, P242-247) 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0019]    As described above, the angle diversity receiving device is required to be able to avoid decrease of the reception level even though an arriving angle of a radio wave changes, and to maintain the diversity effect even though a condition of tropospheric scatter propagation changes. 
         [0020]    An object of the invention is to provide an angle diversity receiving device and an angle diversity receiving method which can avoid decrease of the reception level even though an arriving angle of a radio wave changes, and to maintain the diversity effect even though a condition of tropospheric scatter propagation changes. 
       Solution to Problem 
       [0021]    The angle diversity receiving device of the invention is an angle diversity receiving device which performs angle diversity reception by configuring branches of an angle diversity in accordance with received signals of an array antenna and the angle diversity receiving device includes a plurality of phased array synthesizing means for generating a received signal of the branch by performing phased array synthesis for the received signals of a plurality of antenna elements included in the array antenna and correlation control means for outputting a correlation value between two received signals of the branches, and the phased array synthesizing means controls an angular difference in orientations of the branches for which the correlation value is calculated so that the correlation value decreases. 
         [0022]    The angle diversity receiving method of the invention is an angle diversity receiving method in which angle diversity reception is performed by configuring branches of diversity in accordance with received signals of an array antenna, and the method includes generating a received signal of a branch by performing phased array synthesis for the received signals of a plurality of antenna elements included in the array antenna, outputting a correlation value for two received signals of the branches and controlling an angular difference in orientations between the branches for which the correlation value is calculated so that the correlation value decreases. 
       Advantageous Effect of Invention 
       [0023]    The angle diversity receiving device and the angle diversity receiving method of the invention can avoid decrease of a reception level even though an arriving angle of a radio wave changes, and can maintain a diversity effect even though a condition of tropospheric scatter propagation changes. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0024]      FIG. 1  is a brief block diagram illustrating a configuration of an angle diversity receiving device of a first exemplary embodiment of the invention. 
           [0025]      FIG. 2  is a brief block diagram illustrating a form of a specific configuration of the angle diversity receiving device illustrated in  FIG. 1 . 
           [0026]      FIG. 3  is a block diagram explaining an operation of the angle diversity receiving device. 
           [0027]      FIG.4  is a block diagram illustrating a relationship between a correlation value between branches of the angle diversity and distance of orientations (angular difference between beams). 
           [0028]      FIG. 5  is a brief block diagram illustrating a configuration of an angle diversity receiving device of a second exemplary embodiment of the invention. 
           [0029]      FIG. 6  is a block diagram illustrating an example of a specific configuration of the angle diversity receiving device illustrated in  FIG. 5 . 
           [0030]      FIG. 7  is a block diagram illustrating a configuration of an angle diversity receiving device related to the invention. 
           [0031]      FIG. 8  is a block diagram explaining tropospheric scatter propagation. 
           [0032]      FIG. 9  is a block diagram explaining an operation of the angle diversity receiving device of a related technology. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Exemplary Embodiment 
       [0033]      FIG. 1  is a brief block diagram illustrating a configuration of an angle diversity receiving device  100  of a first exemplary embodiment of the invention. In  FIG. 1 , the angle diversity receiving device  100  of the first exemplary embodiment includes an array antenna  10 , M phased array synthesizing circuits  121  to  12 M, M adaptive matched filters  131  to  13 M, a diversity synthesizing circuit  140 , an automatic equalization circuit  150 , and a correlation control circuit  160 . The array antenna  10  includes N antenna elements  111  to  11 N. Here, each of M and N is an integer which is two or more than two, and M is equal to N or less than N. 
         [0034]    Received signals from the antenna elements  111  to  11 N are inputted to the phased array synthesizing circuits  121  to  12 M. Each of the phased array synthesizing circuits  121  to  12 M selects two or more than two received signals from the received signals received from the antenna elements  111  to  11 N and performs phased array synthesis. The phased array synthesizing circuits  121  to  12 M form M branches. Then, outputs of the phased array synthesizing circuits  121  to  12 M are inputted into M adaptive matched filters  131  to  13 M, respectively, and synthesized by diversity synthesizing circuit  140 . In this way, the angle diversity synthesis is performed to M branches. An output of the diversity synthesizing circuit  140  is automatically equalized by the automatic equalization circuit  150  and consequently a received data signal is acquired. 
         [0035]    The angle diversity receiving device  100  controls orientations of the branches as an arrive direction of a radio wave changes, by using the phased array synthesizing circuits  121  to  12 M connecting to the plurality of antenna elements. The angle diversity receiving device  100  forms a plurality of sub-arrays from among the plurality of branches, and utilizes outputs of the sub-arrays as the received signals of the branches of the angle diversity. The angle diversity receiving device  100  performs adaptive matched filtering between the branches of the angle diversity, performs maximal ratio synthesizing including time-dispersed multi paths, and performs optimal angle diversity reception. 
         [0036]    In the first exemplary embodiment, the correlation control circuit  160  calculates a correlation value between two outputs selected from outputs of the phased array synthesizing circuits  121  to  12 M. The calculated correlation value is inputted into the phased array synthesizing circuit which outputs the two selected signals. The correlation control circuit  160  may sequentially calculate a correlation value between two outputs in M outputs of the phased array synthesizing circuits  121  to  12 M. 
         [0037]      FIG. 2  is a block diagram illustrating a form of a specific configuration of the angle diversity receiving device  100  illustrated in  FIG. 1 . 
         [0038]    An angle diversity receiving device  100   a  includes the array antenna  10 , the phased array synthesizing circuits  121  and  122 , adaptive matched filters (AMF)  131  AND  132 , the diversity synthesizing circuit  140 , the correlation control circuit (CORR)  160 , and the automatic equalization circuit (decision feedback equalizer, DFE)  150 . The array antenna  10  includes antenna elements  11   a  and  11   b.    
         [0039]    Further, the angle diversity receiving device  100   a  includes, between the array antenna  10  and the phased array synthesizing circuits  121  and  122 , the band pass filters (BPF)  221  and  222 , the low noise amplifiers (LNA)  231  and  232 , the received frequency converters (down converter, D/C)  241  and  242 , and the automatic gain controllers (AGC)  251  and  252 . 
         [0040]    Functions of the band pass filters  221  and  222 , the low noise amplifiers  231  and  232 , the received frequency converters  241  and  242 , and the automatic gain controllers  251  and  252  are similar to those of the blocks having the same name shown in  FIG. 7 . 
         [0041]    In  FIG. 2 , the number of the diversity branches is two. Further, the array antenna  10  includes the antenna elements  111  and  112 . Incidentally, each of the antenna elements  111  and  112  may be a horn antenna with an antenna reflector. 
         [0042]    The angle diversity receiving device  100   a  performs linear synthesis of received signals received by the antenna elements  111  and  112 , in the phased array synthesizing circuits  121  and  122 . Thereby the angle diversity receiving device  100   a  controls the phased array. 
         [0043]    The correlation control circuit  160  calculates correlation between an output signal of the phased array synthesizing circuit  121  and an output signal of the phased array synthesizing circuit  122  and outputs the calculated correlation to the phased array synthesizing circuits  121  and  122 . 
         [0044]    Here, a complex coefficient by which each sub-array is multiplied in the phased array synthesizing circuit  121  is represented as W 1 , and a complex coefficient by which each sub-array is multiplied in the phased array synthesizing circuit  122  is represented as W 2 . 
         [0045]    W 1  is multiplied by a signal of each sub-array in a complex multiplier  19   a  or a complex multiplier  19   b.  Outputs of the complex multipliers  19   a  and  19   b  are added in an adder  19   c  and the sum of the outputs of the complex multipliers  19   a  and  19   b  is outputted from the phased array synthesizing circuit  121 . W 2  is multiplied by a signal of each sub-array in a complex multiplier  20   a  or a complex multiplier  20   b.  Outputs of the complex multipliers  20   a  and  20   b  are added in an adder  20   c  and the sum of the outputs of the complex multipliers  20   a  and  20   b  is outputted from the phased array synthesizing circuit  122 . 
         [0046]    The complex coefficient W 1  is adjusted on the basis of the output of the phased array synthesizing circuit  121  and the correlation value inputted from the correlation control circuit  160  so that the output of the phased array synthesizing circuit  121  is maximized. 
         [0047]    Further, the complex coefficient W 2  is adjusted on the basis of the output of the phased array synthesizing circuit  122  and the correlation value inputted from the correlation control circuit  160  so that the output of the phased array synthesizing circuit  122  is maximized. 
         [0048]    Specifically, weighting coefficients W 1  and W 2  are calculated in accordance with following adaptive algorithm. 
         [0000]        W 1( n+ 1)= W 1( n )+(1−μ)[ r 1*( n )· y 1( n )]  (Equation 1)
 
         [0000]        W 2( n+ 1)= W 2( n )+(1−μ)[ r 2*( n )· y 2( n )]  (Equation 2),
 
         [0049]    where r 1  and r 2  are input signal vectors of the phased array synthesizing circuits  121  and  122 , respectively (two-dimensional vectors in  FIG. 2 ), y 1  and y 2  are output signal vectors of the phased array synthesizing circuits  121  and  122 , respectively, a symbol * represents complex conjugate, n in the parenthesis represents a nth sample, μ represents an adjustment coefficient. In Equation 1 and Equation 2, since the algorithm is positive feedback type, (1−μ) is multiplied in order to avoid divergence of the calculation result and sequentially multiply by a multiplier for adaptively converging. 
         [0050]    According to the algorithm described above, the phased array synthesizing circuits  121  and  122  separately control the orientation of the diversity branch to maximize a reception level. Explanatory drawing of the operations are shown in  FIG. 3 . DR 1   a  is a beam of an antenna of a first diversity branch of the phased array synthesizing circuit  121 . DR 1   b  is a beam of the antenna of a second diversity branch of the phased array synthesizing circuit  122 . An angle of each orientation is variable. 
         [0051]    A case is explained, in which the angle diversity receiving devices  100  and  100   a  of the first exemplary embodiment are applied to tropospheric scatter propagation. 
         [0052]    Tropospheric scatter propagation is explained again by using  FIG. 8 . An array antenna of a receiving station (angle diversity receiving devices  100  and  100   a ) corresponds to the receiving antenna  812 . A transmission beam transmitted from the transmitting station  811  is scattered in the troposphere. The scattering region is called a scattering volume and includes spatial extent. A signal from the first scattering point STa in the orientation DTa and a signal from the second scattering point STb in the orientation DTb arrive at the receiving antenna  812  of the over-the-horizon receiving station (angle diversity receiving devices  100  and  100   a ). 
         [0053]    Here, the scattering points STa and STb are spatially separated and each scattering phenomenon randomly changes. The scattering phenomena at the scattering points STa and STb are therefore uncorrelated one another. A received signals between the orientations DTa and DTb are an uncorrelated fading signal one another. 
         [0054]    Therefore, if a plurality of receiving elements having an angular difference therebetween (e.g. DR 1   a,  DR 1   b  in  FIG. 3 ) receive a signal in the orientation DTa and a signal in the orientation DTb, it is possible to synthesize branches of diversity which are uncorrelated one another and to perform angle diversity. 
         [0055]    Incidentally, in actual scatter propagation, when the scattering points STa and STb are spatially closed to each other, signals from the scattering points are not perfectly uncorrelated and include some degree of correlation. Patent Literature 2 describes if a correlation value between branches of angle diversity is equal to or less than 0.6, the angle diversity is effective. 
         [0056]    If spatial distance between the scattering points STa and STb increases, the correlation value decreases and an angle between the orientations DTa and DTb increases. In the invention, the beams of DR 1   a  and DR 1   b  which increase an angle between the branches of the angle diversity are arranged by controlling an orientation of the phased array, and the correlation value is decreased to maintain the diversity effect. 
         [0057]      FIG. 4  is a block diagram illustrating a relationship between a correlation value between the branches of the angle diversity and a distance of orientations (angular difference between beams). In  FIG. 4 , a vertical axis represents a correlation value η between the branches of the angle diversity and a horizontal axis represents an angular difference Δθ between beams of the branches. As shown in  FIG. 4 , the correlation value η between the branches of the angle diversity decreases as the angular difference between beams of the branches Δθ increases. 
         [0058]    The orientation vectors (directionality) G 1  and G 2  of DR 1   a  and DR 1   b  shown in  FIG. 3  are defined as follows. 
         [0000]        G 1= g 1·exp( jθ 1)   (Equation 3)
 
         [0000]        G 2= g 2·exp( jθ 2)   (Equation 4)
 
         [0059]    in the above equations 3, 4, g 1  is an amplitude of an directional vector in the beam of DR 1   a,  θ 1  is an angle of elevation of the directional vector, g 2  is an amplitude of an directional vector in the beam of DR 1   b,  and θ 2  is an angle of elevation of the directional vector. 
         [0060]    The vectors G 1  and G 2  are directional vectors which the branches show when outputs of the phased array synthesizing circuits  121  and  122  are maximized. When the scattering points STa and STb shown in  FIG. 8  come close to each other, the directionality G 1  and the directionality G 2  may come close one another according to circumstances. In this case, the correlation value between the branches increases and the diversity effect is decreased. In the invention, the correlation value between the branches is calculated and the vector G 1  is multiplied by exp(+jΔθ/2) so that the correlation value decreases, i.e. the angular difference Δθ is increased, on the basis of the relationship shown in shown in  FIG. 4 . The vector G 2  is multiplied by exp(−jΔθ/2). With respect to G 1  and G 2 , perturbation correction on Δθ is performed as follows. 
         [0000]        G 1= g 1·exp( jθ 1)·exp(+ jΔθ/ 2)   (Equation 5)
 
         [0000]        G 2= g 2·exp( jθ 2)·exp(− jΔθ/ 2)   (Equation 6)
 
         [0061]    When the perturbation correction on the orientation vectors G 1  and G 2  is performed, the angle diversity effect can be maintained while keeping correlation between the angle diversity low. 
         [0062]    As the result, the angle diversity receiving device of the first exemplary embodiment can avoid decrease of the reception level even though a radio wave arriving angle changes, and can maintain the diversity effect even though a condition of tropospheric scatter propagation changes. 
         [0063]    Additionally, the angle diversity receiving device  100  illustrated in  FIG. 1  can be configured also as follows. 
         [0064]    The angle diversity receiving device  100  is an angle diversity receiving device which performs angle diversity reception by configuring branches of the angle diversity using received signals of an array antenna. Then, the angle diversity receiving device  100  includes the array antenna, phased array synthesizing circuits  20 - 1  to  20 -N, and the correlation control circuit  160 . 
         [0065]    The phased array synthesizing circuits  201  to  20 N perform phased array synthesis of received signals of a plurality of antenna elements included in the antenna array to generate received signals of the branches. The correlation control means outputs a correlation value between the received signals of the branches. The phased array synthesizing circuits  201  to  20 N control an angular difference of orientations between the branches so that the correlation value outputted from the correlation control means  160  decreases. 
         [0066]    In such configuration, the angle diversity receiving device  100  can avoid decrease of the reception level even though the radio wave arriving angle changes, by performing phased array synthesis. Then, the angle diversity receiving device  100  can maintain the diversity effect even though a condition of tropospheric scatter propagation changes, by controlling an angular difference of orientations between the branches so that the correlation value between the branches decreases. 
       Second Exemplary Embodiment 
       [0067]      FIG. 5  is a brief block diagram illustrating a configuration of an angle diversity receiving device  200  of a second exemplary embodiment of the invention. The angle diversity receiving device  200  differs from the first exemplary embodiment in that mutual correlation between outputs of a plurality of phased array synthesizing circuits is calculated by using a complex tap multiplication coefficient of an adaptive matched filter. 
         [0068]    Namely, referring to  FIG. 5 , the complex tap multiplication coefficients of the adaptive matched filters  131  to  13 M are inputted into the correlation control circuit  160 , and the correlation control circuit  160  calculates a correlation value on the basis of complex tap multiplication coefficients of two adaptive matched filters selected from the adaptive matched filters  131  to  13 M. Incidentally, a configuration and basic operations of the angle diversity receiving device  200  except an inputting part for the correlation control circuit  160  are similar to the angle diversity receiving device  100  illustrated in  FIG. 1 , and therefore detailed explanations thereof are omitted. 
         [0069]      FIG. 6  is a block diagram illustrating an example of a specific configuration of the angle diversity receiving device  200  illustrated in  FIG. 5 . Referring to  FIG. 6 , an angle diversity receiving device  200   a  includes, just like the angle diversity receiving device  100   a,  the array antenna  10 , the phased array synthesizing circuits  121  and  122 , the adaptive matched filters (AMF)  131  and  132 , the diversity synthesizing circuit  140 , the correlation control circuit (CORR)  160 , and the automatic equalization circuit (decision feedback equalizer, DFE)  150 . The array antenna  10  includes antenna elements  11   a  and  11   b.    
         [0070]    The angle diversity receiving device  200   a  further includes, between the array antenna  10  and the phased array synthesizing circuits  121  and  122 , the band pass filters (BPF)  221  and  222 , the low noise amplifiers (LNA)  231  and  232 , the received frequency converters (down converter, D/C)  241  and  242 , and the automatic gain controllers (AGC)  251  and  252 . 
         [0071]    The band pass filters  221  and  222 , the low noise amplifiers  231  and  232 , the received frequency converters  241  and  242 , and the automatic gain controllers  251  and  252  have the same functions as those of the blocks with the same name shown in  FIG. 7 . 
         [0072]    That is, the number of diversity branches of the angle diversity receiving device  200   a  shown in  FIG. 6  is two. Each of the antenna elements  111  and  112  may be the horn antenna having the antenna reflector. 
         [0073]    The angle diversity receiving device  200   a  linearly synthesizes received signals of the antenna elements  111  and  112  with the phased array synthesizing circuits  121  and  122 . Thereby control of a phased array is performed. 
         [0074]    In the angle diversity receiving device  200   a,  mutual correlation between an output of the phased array synthesizing circuit  121  and an output of the phased array synthesizing circuit  122  is calculated by using the complex tap multiplication coefficients of the adaptive matched filters  131  and  132 . 
         [0075]    That is, correlation control circuit  160  calculates a correlation value between the complex tap multiplication coefficient of the adaptive matched filter  131  and the complex tap multiplication coefficient of the adaptive matched filter  132  and outputs the calculated correlation value to the phased array synthesizing circuits  121  and  122 . 
         [0076]    Here, a complex coefficient by which each sub-array is multiplied in the phased array synthesizing circuit  121  is represented as W 1 , and a complex coefficient by which each sub-array is multiplied in the second phased array synthesizing circuit  122  is represented as W 2 . 
         [0077]    The complex coefficient W 1  is adaptively-adjusted on the basis of the output of the phased array synthesizing circuit  121  and the correlation value inputted from the correlation control circuit  160 , so that the output of the phased array synthesizing circuit  121  is maximized. 
         [0078]    The complex coefficient W 2  is adaptively-adjusted on the basis of the output of the phased array synthesizing circuit  122  and the correlation value inputted from the correlation control circuit  160 , so that the output of the phased array synthesizing circuit  122  is maximized. 
         [0079]    The values of W 1  and W 2  are calculated by Equation 1 and Equation 2, like the first exemplary embodiment. The orientation vectors (directionality) of angle diversity branches G 1  and G 2  are calculated by Equation (3) to Equation (6). 
         [0080]    In this configuration, when outputs of the phased array synthesizing circuits  121  and  122  are maximized by using Equations (1) to (6) described in the first exemplary embodiment and when the perturbation correction on the orientation vectors G 1  and G 2  is performed, the angle diversity effect can be maintained while keeping correlation between the angle diversity low. 
         [0081]    Consequently, the angle diversity receiving device of the second exemplary embodiment can avoid decrease of the reception level even though the radio wave arriving angle changes, and can maintain the diversity effect even though a condition of tropospheric scatter propagation changes, just like the angle diversity receiving device of the second exemplary embodiment. 
       Third Exemplary Embodiment 
       [0082]    An angle diversity receiving device of a third exemplary embodiment of the invention includes a plurality of phased array synthesizing circuits for performing phased array synthesis of received signals of a plurality of antenna elements, as branches, by performing multiplication and addition of complex coefficients, a correlation control circuit for controlling an angular difference between orientations of branches so that a correlation value between the branches is minimized, on the basis of each output of the plurality of phased array synthesizing circuit, a plurality of adaptive matched filters to which outputs of the plurality of phased array synthesizing circuit are inputted, a diversity synthesizing circuit for performing angle diversity synthesis by synthesizing outputs of the plurality of adaptive matched filters, and an automatic equalization circuit for automatically equalizing an output of the diversity synthesizing circuit. 
       Fourth Exemplary Embodiment 
       [0083]    An angle diversity receiving device of a fourth exemplary embodiment of the invention includes a plurality of phased array synthesizing circuits for performing phased array synthesis of received signals of a plurality of antenna elements, as branches, by performing multiplication and addition of complex coefficients, a plurality of adaptive matched filters to which outputs of the plurality of phased array synthesizing circuit are inputted, a diversity synthesizing circuit for performing angle diversity synthesis by synthesizing outputs of the plurality of adaptive matched filters, an automatic equalization circuit for automatically equalizing an output of the diversity synthesizing circuit, a correlation control circuit for controlling an angular difference between orientations of branches so that a correlation value between the branches is minimized on the basis of complex tap multiplication coefficients of the plurality of adaptive matched filters. 
         [0084]    The plurality of antenna elements of the third and the fourth exemplary embodiments of the invention may be horn antennas. 
         [0085]    Needless to say, the invention of the present application is not limited to the above mentioned embodiments and it is to be understood that to the configurations and details of the invention of the present application, various changes can be made within the scope of the invention of the present application. 
         [0086]    This application claims priority from Japanese Patent Application No. 2012-076489 filed on Mar. 29, 2012, and the contents of which are incorporation herein by reference in their entirety. 
       INDUSTRIAL APPLICABILITY 
       [0087]    For example, the angle diversity receiving devices of the first to the fourth exemplary embodiments are applicable to communication employing angle diversity in propagation in which multi path fading occurs. As usage examples, the invention is applicable to tropospheric scatter propagation communication or land mobile communication. 
       REFERENCE SIGNS LIST 
       [0088]      10 ,  611  array antenna 
         [0089]      111 - 11 N,  61 A,  61 B antenna element 
         [0090]      100 ,  100   a,    200 ,  200   a  angle diversity receiving device 
         [0091]      121 - 12 M phased array synthesizing circuit 
         [0092]      131 - 13 M adaptive matched filter 
         [0093]      140  diversity synthesizing circuit 
         [0094]      150  automatic equalization circuit 
         [0095]      160  correlation control circuit 
         [0096]      19   a,    19   b,    20   a,    20   b  complex multiplier 
         [0097]      19   c,    20   c  adder 
         [0098]      160  correlation control circuit (CORR) 
         [0099]      221 ,  222  band path filter (BPF) 
         [0100]      231 ,  232  low noise amplifier (LNA) 
         [0101]      241 ,  242  reception frequency converter (down converter, D/C) 
         [0102]      251 ,  252  automatic gain controller (AGC) 
         [0103]      811  transmitting station 
         [0104]      812  receiving antenna