Radar antenna system

1. A method, applied in a radar antenna system comprising a plurality of transmitting sub-arrays and a plurality of receiving sub-arrays, the method comprising:

determining whether an angle of an object in relation to the radar antenna system is greater a specific value and control the plurality of transmitting sub-arrays and the plurality of receiving sub-arrays, such that the radar antenna system selectively operates in one of an amplitude-comparison mono-pulse mode and a phase-comparison mono-pulse mode;

when the angle is greater than the specific value, controlling the plurality of transmitting sub-arrays and the plurality of receiving sub-arrays such that the radar antenna system operates in the phase-comparison mono-pulse mode;

when the angle is smaller than the specific value, controlling the plurality of transmitting sub-arrays and the plurality of receiving sub-arrays such that the radar antenna system operates in the amplitude-comparison mono-pulse mode.

2. The method of claim 1 , wherein a transmitting distance is a distance between a transmitting sub-array and another transmitting sub-array among the plurality of transmitting sub-arrays, a receiving distance is a distance between a receiving sub-array and another receiving sub-array among the plurality of receiving sub-arrays, the transmitting distance is a specific number times compared with the receiving distance, and the specific number is a number of the plurality of receiving sub-arrays.

3. The method of claim 2 , wherein the receiving distance is substantially one half of a wavelength of a wireless signal transmitted by the radar antenna system.

4. The method of claim 2 , wherein an angular scanning scope of the radar antenna system increases as the receiving distance decreases.

5. The method of claim 2 , wherein the receiving distance is smaller than one half of a wavelength of a wireless signal transmitted by the radar antenna system.

6. The method of claim 1 , wherein each transmitting sub-array comprises a transmitting phase center, the transmitting phase centers of the plurality of transmitting sub-arrays are aligned with each other; each receiving sub-array comprises a receiving phase center, the receiving phase centers of the plurality of receiving sub-arrays are aligned with each other.

7. The method of claim 1 , wherein when the radar antenna system operates in the phase-comparison mono-pulse mode, the radar antenna system performs wireless transmission via a least a transmitting sub-array of the plurality of transmitting sub-arrays, and performs wireless reception via at least two receiving sub-arrays of the plurality of receiving sub-arrays.

8. The method of claim 1 , wherein when the radar antenna system operates in the amplitude-comparison mono-pulse mode, the radar antenna system performs wireless transmission via a least two transmitting sub-arrays of the plurality of transmitting sub-arrays, and performs wireless reception via at least two receiving sub-arrays of the plurality of receiving sub-arrays.

9. The method of claim 1 , further comprising:

determining whether the radar antenna system operates in the amplitude-comparison mono-pulse mode or the phase-comparison mono-pulse mode according to the angle of the object in relation to the radar antenna system.

10. The method of claim 1 , further comprising:

when the radar antenna system operates in the amplitude-comparison mono-pulse mode, the radar antenna system forming a plurality of beams towards different directions;

determining whether the angle is greater than the specific value and determining whether to select from the amplitude-comparison mono-pulse mode to the phase-comparison mono-pulse mode according to an energy of an object reflection signal corresponding to at least one of the plurality of beams.