an antenna forming an planar array for example a monopole antenna shows an even directivity of vertical polarization with respect to the azimuth but is null in the direction of the z axis further a microstrip antenna is null with respect to the azimuth but shows the maximum directivity gain in the direction of the z axis therefore which antenna to adopt is determined based on the environment in which the array antenna is mounted or based on the requirements of the system an specific case where array signal processing apparatus 300 according to embodiment 1 is applied will be described with embodiment 2 fig9 is a block diagram showing a configuration of radio communication system 900 in fig9 radio communication system 900 includes radio apparatus 910 and tag 920 in radio communication system 900 radio apparatus 910 transmits an impulse radio ultra wideband ir uwb pulse signal from a radio transmission section not shown tag 920 transmits a response uwb pulse signal to radio apparatus 910 according to a received uwb pulse signal it is possible to apply either of the following three methods to this tag 920 the first method is an active method the second method is a passive method and the third method is a semi passive method the third semi passive method is.