MILLIMETER WAVEBAND TRANSCEIVER, RADAR AND VEHICLE USING THE SAME

• US 20080129408A1
• Filed: 11/02/2007
• Published: 06/05/2008
• Est. Priority Date: 11/30/2006
• Status: Active Grant

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi Automotive Systems Limited (Hitachi, Ltd.)
• Inventors: Nagaishi, Hideyuki, Shinoda, Hiroshi, Matsuura, Kazuo
• Granted Patent: US 7,804,443 B2
• Time in Patent Office: Days
• US Class Current: 333/33
• CPC Class Codes: H01L 2223/6627 Waveguides, e.g. microstrip line, strip line, coplanar line
• CPC Class Codes: H01L 2223/6633 Transition between different waveguide types
• CPC Class Codes: H01L 2924/19032 being a microstrip line type
• CPC Class Codes: H01L 2924/19039 impedance transition between different types of wave guides
• CPC Class Codes: H01P 5/107 Hollow-waveguide/strip-line transitions

Abstract

In a millimeter waveband transceiver using an antenna and a waveguide for a connection line, it is necessary to perform transmission mode line conversion between TEM waves of a microstrip line and VTE01 mode waves of the waveguide. There is a limit to reducing the conversion loss using only a matching box for connecting the microstrip line with the waveguide. In a transmission mode line transducer for converting between the TEM waves of the microstrip line and the VTE01 mode waves of the waveguide, if the cross-sections are substantially the same size, in the case of a 50Ω microstrip line when the characteristic impedance of the waveguide is about 80%, i.e., 40Ω, the line conversion loss can be optimized. Therefore, the microstrip line is connected with the waveguide using a λ/4 matching box via a ridged waveguide having a low impedance and a length of λ/16 or less.

Claims

1. A millimeter waveband transceiver comprising:

a microstrip line;

a standard waveguide; and

a transmission mode transducer provided therebetween,

wherein the transmission mode transducer comprising a waveguide transducer, and

wherein the characteristic impedance of the waveguide transducer is equal to or less than the characteristic impedance of the microstrip line.

2. The millimeter waveband transceiver according to claim 1,

wherein the transmission mode transducer further comprising an vertical transducer that connects the microstrip line with a ridged waveguide of the waveguide transducer at right angles.

3. The millimeter waveband transceiver according to claim 2,

wherein the length of the short side of a cross-sectional opening of the ridged waveguide is twice or more than twice the dielectric thickness of the microstrip line.

4. The millimeter waveband transceiver according to claim 2,

wherein the length of the short side of a rectangle cross-sectional opening of the ridged waveguide is twice or more than twice the dielectric thickness of the microstrip line, and

wherein the ridged waveguide comprising a ridge provided near the center of one or both of the long sides of the ridged waveguide cross-section projecting toward the center of the rectangle, wherein a distance from the nearest part of the opening is twice or less than twice the thickness of the dielectric.

5. The millimeter waveband transceiver according to claim 2,

wherein the ridged waveguide comprising a pair of ridges provided near the centre of one or both of the long sides of a rectangle cross-section of the ridged waveguide, projecting toward the center of the rectangle, wherein a distance from the nearest part of the cross-sectional opening is twice or less than twice the thickness of the dielectric;

wherein the width of one of the ridges is twice or less than twice the width of the microstrip line; and

wherein the width of the other ridge is twice or more than twice the width of the one ridge.

6. The millimeter waveband transceiver according to claim 1,

wherein a λ

/4 matching box is connected between the transmission mode transducer and the standard waveguide, and

the characteristic impedance of this λ

/4 matching box is a higher impedance than the characteristic impedance of the ridged waveguide and microstrip line of the transmission mode transducer, and a lower impedance than the characteristic impedance of the standard waveguide.

7. The millimeter waveband transceiver according to claim 1,

wherein a multilayer substrate is laminated together with a heat transfer plate,

a transmission mode transducer and a first λ

/4 matching box are provided in the multilayer substrate,

wherein the characteristic impedance of the first λ

/4 matching box is a higher impedance than the characteristic impedance of the ridged waveguide and microstrip line of the waveguide transducer, and a lower impedance than the characteristic impedance of the standard waveguide, and

a second λ

/4 matching box, provided in the heat transfer plate, having a lower impedance than the characteristic impedance of the standard waveguide, and a higher impedance than the characteristic impedance of the first λ

/4 matching.

8. The millimeter waveband transceiver according to claim 7,

wherein the opening shape of the first λ

/4 matching box and the opening shape of the second λ

/4 matching box have point symmetry and are non-analogous.

9. The millimeter waveband transceiver according to claim 2,

wherein a metal conductor pattern wider than the microstrip line is provided near the edge of the metal conductor which is the opposite GND electrode of the microstrip line immediately prior to connecting to the ridged waveguide having a smaller characteristic impedance than that of the microstrip line.

10. The millimeter waveband transceiver according to claim 7,

wherein the first λ

/4 matching box is a tapered impedance matching box provided in the multilayer substrate.

11. The millimeter waveband transceiver according to claim 1, the transceiver comprising:

an RF circuit, an antenna, the standard waveguide which constitutes the input and output terminals of the antenna, the microstrip line which is the millimeter waveband data line of the RF circuit, and a λ

/4 matching box connected between the standard waveguide and the waveguide transducer,

wherein the characteristic impedance of the λ

/4 matching box is an intermediate value between the characteristic impedance of the microstrip line and the characteristic impedance of the standard waveguide.

12. The millimeter waveband transceiver according to claim 1, the transceiver comprising:

a multilayer substrate;

an RF circuit control board;

the RF circuit provided on the top layer of the RF circuit control board and the multilayer substrate;

an antenna connected to the undersurface of the multilayer substrate; and

a waveguide transducer and λ

/4 matching box of the transmission mode transducer provided in an inner layer of the multilayer substrate,

wherein the waveguide transducer and λ

/4 matching box waveguide are formed in a waveguide shape through to the multilayer substrate underlayer surface by alternately laminating a dielectric film and a metal conductor film, forming a cutout pattern in the metal conductor film, and electrically connecting the metal conductor films by vias.

13. The millimeter waveband transceiver according to claim 2,

wherein the vertical transducer comprising a ridged waveguide having a ridge projecting near the center of one or both of the long sides of the waveguide cross-section, and having a smaller characteristic impedance than that of the microstrip line,

wherein the ridged waveguide is formed in the multilayer substrate wherein a dielectric film and a metal film are alternately laminated,

wherein the length of the projecting ridge part is λ

/4 or less from the facet of the long side of the rectangular ridged waveguide opening, and

a plurality of vias for making electrical connection are disposed in the projection direction in the multilayer substrate.

14. The millimeter waveband transceiver according to claim 1, the transceiver comprising:

a multilayer substrate;

an antenna connected to the undersurface of the multilayer substrate, and a standard waveguide which constitutes the input and output terminals of the antenna;

wherein the microstrip line which is a millimeter waveband data line provided on the top surface of the multilayer substrate, a waveguide transducer and a first λ

/4 matching box of the transmission mode transducer provided in an inner layer of the multilayer substrate, a heat transfer plate, and an antenna holding plate,

wherein the characteristic impedance of the first λ

/4 matching box is an intermediate value between the characteristic impedance of the microstrip line and the characteristic impedance of the standard waveguide,

a plurality of second λ

/4 matching boxes having a characteristic impedance ratio at the input and output terminals of 3 or less are provided in at least one of the multilayer substrate, the heat transfer plate and the antenna holding plate; and

wherein the first λ

/4 matching box is connected with the standard waveguide by the second λ

/4 matching box.

15. A vehicle radar, comprising a millimeter waveband transceiver with a radar function comprising:

an RF circuit;

a plurality of antennas;

a standard waveguide which constitutes the input and output terminals of the antennas; and

a transmission mode transducer connected respectively between the RF circuit and standard waveguides,

wherein the transmission mode transducer is an vertical transducer that connects the microstrip line of the RF circuit with the ridged waveguide at right angles, and

wherein the characteristic impedance of the ridged waveguide is equal to or less than the characteristic impedance of the microstrip line.

16. The vehicle radar according to claim 15,

wherein the RF circuit and the antennas are superimposed on each other with the heat transfer plate sandwiched therebetween, and

wherein the connection line is formed by the vertical transducer and λ

/4 matching box.

17. The vehicle radar according to claim 15, the radar comprising:

a first λ

/4 matching box connected between the standard waveguide and the transmission mode transducer;

a multilayer substrate;

a heat transfer plate; and

an antenna holding plate,

wherein the characteristic impedance of the first λ

/4 matching box is an intermediate value between the characteristic impedances of the microstrip line and the standard waveguide,

a plurality of second λ

/4 matching boxes having a characteristic impedance at the input and output terminals of 3 or less are provided in at least one of the multilayer substrate, the heat transfer plate and the antenna holding plate, and wherein the first λ

/4 matching box and the standard waveguide are connected by the second λ

/4 matching box.

18. A vehicle comprising:

a millimeter waveband transceiver mounted on the vehicle, the vehicle having a radar function; and

an electronic circuit that controls the vehicle based on information from the millimeter waveband transceiver,

wherein the millimeter waveband transceiver comprising an RF circuit, a plurality of antennas, a standard waveguide which constitutes the input and output terminals of the plurality of antennas, and a transmission mode transducer connected respectively between the RF circuit and standard waveguides,

wherein the transmission mode transducer is an vertical transducer that connects the microstrip line of the RF circuit with a ridged waveguide at right angles, and

wherein the characteristic impedance of the ridged waveguide is equal to or less than the characteristic impedance of the microstrip line.

19. The vehicle according to claim 18,

wherein the RF circuit and plurality of antennas are superimposed on each other with a heat transfer plate sandwiched therebetween, and

wherein the RF circuit and antenna connection lines are formed by the vertical transducer and the λ

/4 matching box.

20. The vehicle according to claim 19,

wherein the RF circuit and λ

/4 matching box are formed by a multilayer substrate, and

wherein the multilayer substrate is attached to one side of the antenna holding plate via the heat transfer plate, and the plurality of antennas are attached to the other side of the antenna holding plate.