Millimeter waveband transceiver, radar and vehicle using the same

• US 7,804,443 B2
• Filed: 11/02/2007
• Issued: 09/28/2010
• Est. Priority Date: 11/30/2006
• Status: Active Grant

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Nagaishi, Hideyuki, Shinoda, Hiroshi, Matsuura, Kazuo
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Bythrow; Peter M
• Application Number:
  US11/934,705
• Publication Number:
  US 20080129408A1
• Time in Patent Office: 1,061 Days
• Field of Search: 342 70- 72, 342/175, 343/711, 343/713, 343/762, 343/772, 333/26, 333/33, 333/247, 333/248
• US Class Current: 342/70
• 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 between the microstrip line and the standard waveguide,

wherein the transmission mode transducer comprises a waveguide transducer,

wherein the waveguide transducer is a ridged waveguide, and

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

2. The millimeter waveband transceiver according to claim 1, wherein the ridged waveguide is a vertical transducer, and the microstrip line is connected to the ridged waveguide at a right angle.

3. The millimeter waveband transceiver according to claim 2, wherein a length of a short side of a cross-sectional opening of the ridged waveguide, which is parallel to a propagation direction of a millimeter waveband signal, is twice or more than twice a dielectric thickness of the microstrip line.

4. The millimeter waveband transceiver according to claim 2,

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

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

5. The millimeter waveband transceiver according to claim 2,

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

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

wherein a 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

wherein a characteristic impedance of the λ

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

wherein a transmission mode transducer and a first λ

/4 matching box are provided in the multilayer substrate,

wherein a characteristic impedance of the first λ

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

wherein a second λ

/4 matching box, provided in the heat transfer plate, has 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 box.

8. The millimeter waveband transceiver according to claim 7, wherein an opening shape of the first λ

/4 matching box and an 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 an edge of a 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 further comprising:

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

/4 matching box is connected between the standard waveguide and the ridged waveguide,

wherein a characteristic impedance of the λ

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

12. The millimeter waveband transceiver according to claim 1, the transceiver further 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 an undersurface of the multilayer substrate; and

the waveguide transducer and a λ

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

wherein the ridged waveguide of the waveguide transducer and the λ

/4 matching box are formed in a waveguide shape through to the underlayer surface of the multilayer substrate by alternately laminating a dielectric film and a metal conductor film, forming a cutout pattern of 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 the ridged waveguide has a ridge projecting near a center of one or both long sides of a waveguide cross-section, and has a smaller characteristic impedance than that of the microstrip line,

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

wherein a length of the projecting ridge is λ

/4 or less from a facet of one of said long sides of the rectangular ridged waveguide opening, and

wherein 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 further comprising:

a multilayer substrate;

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

a standard waveguide which constitutes input and output terminals of the antenna,

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

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

wherein a characteristic impedance of the first λ

/4 matching box is an intermediate value between the characteristic impedance of the microstrip line and a 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 to 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 respective 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 a vertical transducer that connects a microstrip line of the RF circuit to a ridged waveguide thereof at a right angle, and

wherein a characteristic impedance of the ridged waveguide is equal to or less than a 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 a heat transfer plate sandwiched therebetween, and

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

/4 matching box.

17. The vehicle radar according to claim 15, further 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 a 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 comprises an RF circuit, a plurality of antennas, a standard waveguide which constitutes 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 a vertical transducer that connects the microstrip line of the RF circuit to a ridged waveguide at a right angle, and

wherein a characteristic impedance of the ridged waveguide is equal to or less than a 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 a λ

/4 matching box.

20. The vehicle according to claim 19,

wherein the RF circuit and the 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.