# US 10,320,049 B2 · Annular directional coupler, in particular for microwave-based distance sensors

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- Number: US 10,320,049 B2
- Document ID: US10320049B2
- Status: Granted
- Kind: B2
- Application number: 15/712,451
- Filed: 2017-09-22
- Published: 2018-03-29
- Granted: 2019-06-11
- Earliest claimed: 2016-09-23
- Assignees: Balluff GmbH
- Applicants: Balluff GmbH
- Inventors: József Geisz
- Web page: https://patentgrep.com/patent/US10320049B2

## CPC

- H01P 5/188: {the guides being dielectric waveguides}
- G01S 7/034: {Duplexers (switching devices for waveguides H01P1/10; transmit-receive switching in transceivers H04B1/44)}
- G01S 7/40: Means for monitoring or calibrating
- G01S 13/04: Systems determining presence of a target (based on relative movement of target G01S13/56)
- G01S 13/36: with phase comparison between the received signal and the contemporaneously transmitted signal
- G01V 3/12: operating with electromagnetic waves {(operating with millimetre waves G01V8/005)}
- H01P 5/04: with variable factor of coupling
- H01P 5/222: {180° rat race hybrid rings}
- H01P: WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE (operating at optical frequencies G02B)
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)

## Abstract

An annual directional coupler having at least three taps, which are each arranged relative to one another around routes having a wavelength difference of ¼ of a wave guide wavelength, includes in particular at least two branch lines, wherein a first branch line has at least three taps and wherein the at least second branch line does not have any taps and is supplemented by an additional route corresponding to the wave guide wavelength.

## Claims

### Claim 1

An annular directional coupler having at least three taps which are each arranged relative to one another around routes having a wavelength difference of ¼ of a wave guide wave length, comprising at least two branch lines,
wherein a first branch line has at least three taps;
wherein the at least second branch line does not have any taps and is supplemented by an additional route corresponding to the wave guide wavelength; and
wherein the routes arranged relative to one another between the taps having a wavelength difference of ¼ of the wave guide wavelength and the additional routes are formed by T-pads.

### Claim 2 (depends on 1)

The directional coupler according to claim 1, wherein the T-pads each have a capacitor between a wave guide and a ground potential.

### Claim 3 (depends on 2)

The directional coupler according to claim 2, wherein the directional coupler is tunably formed by means of the capacitors.

### Claim 4 (depends on 1)

The directional coupler according to claim 1, wherein the additional routes corresponding to the wave guide wavelength are calculated by means of a Mo matrix for a lossless wave guide and the matrix product Mo=MxMcMx.

### Claim 5 (depends on 4)

The directional coupler according to claim 4, wherein the matrix product Mo is formed by means of a first transfer matrix for the lossless wave guide of the shape
M
x
=
[
A
x
B
x
C
x
D
x
]
=
[
cos
⁢
⁢
θ
x
jZx
⁢
⁢
s
⁢
⁢
in
⁢
⁢
θ
⁢
x
jZ
x
-
1
⁢
⁢
sin
⁢
⁢
θ
x
cos
⁢
⁢
θ
x
]
and by means of a second transfer matrix
M
c
=
[
A
c
B
c
C
c
D
c
]
=
[
1
0
j
⁢
⁢
ω
⁢
⁢
C
1
]
that takes a capacitor into consideration.