# US 2004/0160291 A1 · Microwave coupler

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- Number: US 2004/0160291 A1
- Document ID: US20040160291A1
- Status: Published application
- Kind: A1
- Application number: 10/366,729
- Filed: 2003-02-14
- Published: 2004-08-19
- Earliest claimed: 2003-02-14
- Assignees: Microlab/FXR
- Inventors: Marek E. Antkowiak; Andrzej Sawicki
- Web page: https://patentgrep.com/patent/US20040160291A1

## CPC

- H01P 5/185: {Edge coupled lines}
- H01P 5/18: consisting of two coupled guides, e.g. directional couplers
- H01P: WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE (operating at optical frequencies G02B)

## Abstract

A high power, TEM mode directional microwave coupler having low loss and expanded bandwidth uses novel thick suspended substrate conductors to provide multi-octave bandwidth performance in a practical package. Each of two center conductors is formed using metal layer deposited onto three surfaces of a thick dielectric substrate. The conductors, which can be edge-coupled or offset-coupled, form a novel structure in which the non-metallized side of the substrate is oriented toward the facing outside vertical walls. This effectively reduces the effect of the package wall on the coupling structure, permitting a smaller, constant-width dimension, which in turn raises the waveguide cut-off frequency. The result is a directional coupler with an extended high frequency performance, with reduced physical size and low loss.

## Claims

### Claim 1

A directional coupler comprising:
a housing, the housing forming an outer conductor;
a dielectric within said housing;
a primary transmission path including a thick primary transmission line disposed in a first plane within said dielectric; and
a secondary transmission path including a thick secondary transmission line disposed in a second plane within said dielectric and having a portion in coupling proximity with said primary transmission line to form a continuously coupled section,
wherein the first and second planes are substantially parallel or coplanar.

### Claim 2 (depends on 1)

The coupler of claim 1, wherein the dielectric is air, gas or vacuum.

### Claim 3 (depends on 1)

The coupler of claim 1, wherein the coupler operates in a transverse electromagnetic mode (TEM).

### Claim 4 (depends on 1)

The coupler of claim 1, wherein each of the primary and secondary transmission lines includes a dielectric substrate having a substantially constant thickness and metallization arranged on the dielectric substrate.

### Claim 5 (depends on 4)

The coupler of claim 4, wherein the metallization is arranged on three surfaces of the dielectric substrate.

### Claim 6 (depends on 5)

The coupler of claim 5, wherein one of the three surfaces of the dielectric substrate is substantially perpendicular to another of the three surfaces of the dielectric substrate.

### Claim 7 (depends on 5)

The coupler of claim 5, wherein one of the three surfaces of the dielectric substrate generally faces the other transmission line.

### Claim 8 (depends on 5)

The coupler of claim 5, wherein a fourth surface of the dielectric substrate does not have metallization arranged thereon, the fourth surface generally facing away from the other transmission line.

### Claim 9 (depends on 1)

The coupler of claim 1, wherein the coupled section includes a loosely coupled end and a tightly coupled end, a coupling coefficient varying continuously along the coupled section between the loosely coupled and tightly coupled ends.

### Claim 10 (depends on 1)

The coupler of claim 1, wherein the housing includes:
top and bottom walls substantially parallel to the first and second planes; and
side walls substantially perpendicular to the first and second planes.

### Claim 11 (depends on 1)

The coupler of claim 1, wherein the outer conductor is in proximity to the coupled section and influences a characteristic impedance of the coupler.

### Claim 12 (depends on 1)

The coupler of claim 1, wherein the housing includes a tuning post proximate to a diverging point of at least one of the primary and secondary transmission paths.

### Claim 13 (depends on 12)

The coupler of claim 12, wherein the tuning post comprises a generally cylindrical protrusion on an inner surface of the housing.