Patent ID: 8878719
Filing Date: 2014-11-04
Classification: G01S,H01Q

Abstract:
1. A radar apparatus forming a series-feed array-antenna, operating in either a normal mode or a calibration mode, the radar apparatus comprising: a voltage controlled oscillator that changes frequency of a signal to be transmitted from the series-feed array-antenna, the frequency of the signal being changed within a modulation period; an array antenna having a transmission antenna and a reception antenna, each antenna including a plurality of antenna elements arrayed with a feedline electrically connected therebetween, thereby constituting the series-feed array-antenna, wherein the transmission antenna radiates the signal from respective antenna elements having mutually different feeding phases among the respective antenna elements so as to generate a radar beam; a calibration line connected between a connection point at the feedline of the transmission antenna and a connection point at the feedline of the reception antenna; a switch connected between the transmission antenna and the reception antenna to connect or disconnect the calibration line therebetween, the signal having a phase shift being transmitted via the calibration line when the switch connects the calibration line, the switch connecting the calibration line between the transmission antenna and the reception antenna when the radar apparatus operates in the calibration mode; means for calculating an amount of phase shift from the signal transmitted via the calibration line based on a reference phase at the transmission antenna; and means for calibrating the phase shift calculated by the calculating means and the calibration means is configured to convert the phase shift to be a frequency-shift and enables the voltage controlled oscillator to control the frequency of the signal being transmitted by the transmission antenna so as to perform the calibration, wherein the calibration line is connected between the connection points so as to include at least one antenna element in a signal path from a feeding point on the feedline in the transmission antenna to the connection point on the feedline in the transmission antenna and a signal path from the connection point at the feedline in the reception antenna to a feeding point at the feedline in the reception antenna, the modulation period in the calibration mode is set to be longer than that in the normal mode.