Radar apparatus and method for forming reception beam of the same
When an excitation signal is generated from an exciter due to an activation signal generated from a radar control device and is distributed to supply to each antenna sub-module, a combination reception signal is transmitted to a receiver from each antenna sub-module. The receiver takes in the combination reception signal obtained by each sub-module in response to an instruction from the radar control device, a frequency converter converts the combination reception signal into a prescribed frequency band, and a distributed aperture combination circuit performs a beam combination in accordance with a distributed aperture combination algorithm. In this way, a radar apparatus, which is equivalent to an active phased array radar of a large aperture and with high performance, is achieved.
1. A radar apparatus comprising:
a plurality of antenna sub-modules which are separately arranged from each other at arbitrary positions within a preset range, and that function as individual active phased array antennas, and that also function, as a whole, as a single active phased array antenna;
a control device which forms a reception beam by exciting the plurality of antenna sub-modules and by individually and selectively applying directional control; and
a reception processor which obtains a beam combination signal by taking in a reception signal obtained by each of the plurality of antenna sub-modules to apply distributed aperture combination processing to the reception signal.
2. The apparatus according to claim 1 , wherein
the reception processor comprises:
a storage device which stores the reception signals obtained by the plurality of antenna sub-modules along with reception timing in storage areas corresponding to processing range cells;
a weight calculation device which takes in the reception signal obtained by any one of the plurality of antenna sub-modules, estimates a reference signal as a reference of amplitude and phase of the reception signal, and calculates each appropriate weight corresponding to a distance; and
a reception beam combination device which computes a covariance matrix from data of cells assumed to be formed solely from unnecessary waves excluding range cells assumed to include a target signal from the storage device, and combines a reception beam by weighting to an antenna reception signal by means of appropriate weight calculated by the weight calculation device on the basis of the covariance matrix.
3. The apparatus according to claim 1 , wherein
the control device selects a corresponding-module from each coverage range of the plurality of antenna sub-modules in advance.
4. The radar apparatus according to claim 2 , wherein:
the reception beam combination device stores the reception signals obtained by the plurality of antenna sub-modules along with reception timing in storage areas corresponding to processing rages;
estimates a reference signal by defining the reception signal obtained by any one of the plurality of antenna sub-modules as a reference of amplitude and phase to calculate each appropriate weight of range cells corresponding to a distance; and,
computes a covariance matrix from data of cells assumed to be formed solely from unnecessary waves excluding range cells assumed to include a target signal from a storage device, and combines a reception beam by weighting to an antenna reception signal by means of appropriate weight calculated by the weight calculation device on the basis of the covariance matrix.
5. The apparatus according to claim 1 , wherein
the control device selects a corresponding-module from each coverage range of the plurality of the antenna sub-modules in advance, when a target direction is decided.
6. A method for forming a reception beam of a radar apparatus, comprising:
dividing an active phased array antenna that functions, as a whole, as a single active phased array antenna into a plurality of antenna sub-modules that function as individual active phased array antennas, and to install each divided module to be separately arranged from each other at an arbitrary position within a preset range;
forming a reception beam by exciting the plurality of antenna sub-modules to individually and selectively apply direction control; and
combining a beam combination signal by taking in a reception signal each obtained by the plurality of antenna sub-modules to apply distributed aperture combination processing.