# US 2021/0242585 A1 · Matching circuit and antenna device

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- Number: US 2021/0242585 A1
- Document ID: US20210242585A1
- Status: Published application
- Kind: A1
- Application number: 17/050,014
- Filed: 2019-04-15
- Published: 2021-08-05
- Earliest claimed: 2018-04-26
- Assignees: Yokowo Co., Ltd.
- Applicants: Yokowo Co., Ltd.
- Inventors: Yusuke YOKOTA
- Web page: https://patentgrep.com/patent/US20210242585A1

## CPC

- H01Q 1/3275: {mounted on a horizontal surface of the vehicle, e.g. on roof, hood, trunk}
- H01Q 5/335: at the feed, e.g. for impedance matching
- H01Q 1/1214: {through a wall}
- H01Q 1/3233: {particular used as part of a sensor or in a security system, e.g. for automotive radar, navigation systems}
- H01Q 1/362: {for broadside radiating helical antennas}
- H01Q 5/50: Feeding or matching arrangements for broad-band or multi-band operation
- H03H 7/38: Impedance-matching networks
- H04B 1/18: Input circuits, e.g. for coupling to an antenna or a transmission line (coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H)
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)
- H04B: TRANSMISSION

## Abstract

An antenna device configured to be attached to a vehicle includes: an antenna of a resonance type; and a matching circuit connected to the antenna, wherein the matching circuit includes a first matching circuit connected to a feeding portion of the antenna and a second matching circuit connected to a subsequent stage of the first matching circuit, wherein the first matching circuit reduces an impedance in a frequency band that is away to a higher-frequency range or a lower-frequency range from a resonance point of the antenna such that the impedance is lower than before connection of the first matching circuit, and the second matching circuit increases an impedance in a vicinity of the resonance point of the antenna such that the impedance is higher than before connection of the second matching circuit.

## Claims

### Claim 1

An antenna device configured to be attached to a vehicle, comprising:
an antenna of a resonance type; and
a matching circuit connected to the antenna,
wherein the matching circuit includes a first matching circuit connected to a feeding portion of the antenna and a second matching circuit connected to a subsequent stage of the first matching circuit,
wherein the first matching circuit reduces an impedance in a frequency band that is away to a higher-frequency range or a lower-frequency range from a resonance point of the antenna such that the impedance is lower than before connection of the first matching circuit, and the second matching circuit increases an impedance in a vicinity of the resonance point of the antenna such that the impedance is higher than before connection of the second matching circuit.

### Claim 2 (depends on 1)

The antenna device according to claim 1, wherein:
the first matching circuit includes a first reactance element of a grounded type; and
the second matching circuit includes a second reactance element that is a non-grounded type and has a polarity different from that of the first reactance element.

### Claim 3 (depends on 1)

The antenna device according to claim 1, wherein:
the antenna is an antenna in which an impedance is capacitive in a first frequency band, and the impedance is inductive in a second frequency band that is higher than the first frequency band; and
the first matching circuit makes the impedance in the second frequency band of the antenna more capacitive than before connection of the circuit.

### Claim 4 (depends on 1)

The antenna device according to claim 1, wherein:
the antenna is an antenna in which an impedance is capacitive in a first frequency band, and the impedance is inductive in a second frequency band that is higher than the first frequency band; and
the first matching circuit makes the impedance in the first frequency band of the antenna more inductive than before connection of the circuit.

### Claim 5 (depends on 1)

The antenna device according to claim 1, wherein the matching circuit is configured by a plurality of sets of the first matching circuit and the second matching circuit connected in cascade.

### Claim 6 (depends on 1)

The antenna device according to claim 1, wherein the matching circuit includes a third matching circuit of a non-grounded type connected to a preceding stage of the first matching circuit.

### Claim 7

A matching circuit connected to an antenna of a resonance type, comprising:
a first matching circuit connected to a feeding portion of the antenna; and
a second matching circuit connected to a subsequent stage of the first matching circuit,
wherein the first matching circuit reduces an impedance in a frequency band that is away to a higher-frequency range or a lower-frequency range from a resonance point of the antenna such that the impedance is lower than before connection of the first matching circuit, and the second matching circuit increases an impedance in the vicinity of the resonance point of the antenna such that the impedance is higher than before connection of the second matching circuit.