Microstrip Array Antenna With Bent Feeding Strip Line

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Solution Overview

Problem

Conventional microstrip array antennas used in automotive radars suffer from asymmetrical radiation pattern characteristics due to differing connection angles of radiation antenna elements with respect to the feeding strip line, leading to elevated sidelobes that exceed specification values, causing interference and ghosting issues.

Innovation Solution

A microstrip array antenna design featuring a dielectric substrate with a conductive grounding plate and a strip conductor where the feeding strip line has a meandering shape, allowing radiation antenna elements to be connected at a consistent angle of 90° with respect to the feeding strip line, ensuring parallel longitudinal orientations and symmetrical radiation patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If radiation antenna elements are connected with the feeding strip line at different angles on opposite sides, then the antenna can be installed vertically to obtain desired radiation pattern, but the directivity characteristics become asymmetrical and sidelobes are elevated

Engineering Contradiction:

Improveradiation pattern qualityVSAvoiddirectivity symmetry

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies asymmetry by intentionally designing the feeding strip line with a bent shape rather than a straight configuration. This asymmetric geometry allows the radiation antenna elements on opposite sides to be connected at the same angle (e.g., 45 degrees) relative to the feeding strip line, achieving symmetrical directivity characteristics while maintaining the desired asymmetric radiation pattern for vertical installation in automotive radars

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

Instead of connecting radiation antenna elements at different angles on opposite sides of a straight feeding strip line (conventional approach), the patent inverts the approach by using a bent feeding strip line that enables both elements to be connected at the same angle, thereby achieving symmetry in directivity while obtaining the desired asymmetric radiation pattern

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If the feeding strip line is disposed perpendicular to the ground for vertical installation, then the antenna obtains desired radiation pattern in the vertical direction, but plane polarization cannot be inclined with respect to the ground

Engineering Contradiction:

Improvevertical radiation patternVSAvoidpolarization angle

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The bent shape of the feeding strip line introduces asymmetry in the geometric configuration, which enables the radiation antenna elements to be oriented at an angle (e.g., 45 degrees) relative to the vertical direction. This asymmetric design allows the antenna to achieve both vertical radiation pattern and inclined plane polarization simultaneously

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent adds angular orientation as an additional dimension to the vertical installation configuration. By inclining the radiation antenna elements at a predetermined angle relative to the vertical direction through the bent feeding strip line, the antenna achieves polarization control in a different dimensional aspect while maintaining vertical radiation characteristics

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Device complexity

If radiation antenna elements are arranged along straight sides of the feeding strip line, then the structure is simple, but the directivity of elements on both sides cannot have symmetrical characteristics

Engineering Contradiction:

Improvefeeding strip line structureVSAvoiddirectivity symmetry

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent uses an asymmetric bent shape for the feeding strip line to achieve symmetric directivity characteristics. The bend in the feeding strip line creates a configuration where radiation antenna elements on opposite sides can be connected at the same angle, ensuring symmetrical directivity while adding only moderate geometric complexity

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The feeding strip line incorporates a curved or bent geometry instead of a straight configuration. This curvature enables the radiation antenna elements to be positioned and connected at equal angles on both sides of the feeding strip line, achieving symmetrical directivity characteristics while maintaining structural simplicity

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS8624784B2Microstrip array antenna

Publication Date: 2014.01.07 DENSO CORP

AI summary

The present invention provides, as one aspect, a microstrip array antenna including a dielectric substrate, on a back face of which a conductive grounding plate is formed, and a strip conductor formed on the dielectric substrate. The strip conductor comprises a feeding strip line which extends in an extension direction, and at least two radiation antenna elements. At least one of the antenna elements is connected with one side of the strip line, and at least one of the antenna elements is connected with the other side of the strip line. The longitudinal directions of the antenna elements are parallel to each other and are at an angle of other than 90° with respect to the extension direction. The strip line has a bending shape and fully extends in the extension direction so that the antenna elements are connected with the strip line at the same angle.