Radar Antenna Substrate Layout for Directivity Alignment
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Solution Overview
Problem
Existing antenna devices face challenges in achieving desired directivity due to the influence of substrate thickness, which is significant relative to the operating wavelength, especially in high-frequency bands like the millimeter wave band, leading to mismatched radiation directions.
Innovation Solution
The antenna device employs a substrate configuration with a first portion having a thinner thickness than a second portion, allowing at least part of the feed element or director to be formed in the thinner portion, thereby reducing radiation pattern distortion and enabling high-gain antenna operation with improved impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a multilayer substrate is used to accommodate complex wiring and components, then the substrate can integrate feeding lines, feed elements, and component wiring in a single substrate, but the substrate thickness becomes thicker and causes radiation pattern distortion and directivity mismatch in high-frequency bands
Solution Approach 1:
The substrate is divided into a first substrate for high-frequency signal transmission and a second substrate for component wiring, separating the functions to avoid mutual interference and allow each substrate to be optimized for its specific purpose
Solution Approach 2:
Different regions of the substrate structure are assigned different thicknesses and material properties - the first substrate near the feed element has specific thickness characteristics for optimal radiation, while the second substrate provides additional wiring capacity without affecting the radiation characteristics
2Adaptability or versatility
If a thicker substrate is used to support multiple layers for component wiring, then complex wiring can be accommodated, but the substrate thickness becomes non-negligible relative to the operating wavelength, causing the antenna directivity to deviate from the desired radiation direction
Solution Approach 1:
The substrate system is segmented into multiple substrates with distinct functions - the first substrate maintains controlled thickness for antenna performance while the second substrate provides additional wiring layers for components, allowing each to be optimized independently
Solution Approach 2:
The wiring capacity is expanded by adding a second substrate in the vertical dimension rather than increasing the thickness of the first substrate, allowing complex wiring to be accommodated without affecting the radiation characteristics of the antenna element
3Ease of manufacture
If generic substrates like FR-4 are used for component wiring layers, then cost is reduced compared to using high-frequency substrates throughout, but the transmission loss increases in high-frequency bands
Solution Approach 1:
Different substrate materials are used in different locations - the first substrate near the antenna element uses high-frequency material with low loss characteristics, while the second substrate for component wiring uses cost-effective generic substrate material, optimizing both performance and cost
Solution Approach 2:
The substrate system uses a composite structure combining different substrate materials - high-frequency substrate for signal-critical areas and generic substrate for non-critical wiring areas, achieving a balance between performance requirements and manufacturing cost
Data Source
AI summary
According to one embodiment, an antenna device includes a substrate; a feed element provided on or inside the substrate; a feeder line provided on or inside the substrate and configured to feed power to the feed element; and at least one of a director provided on or inside the substrate and away from the feed element, and a reflector provided on or inside the substrate and away from the feed element, wherein the substrate includes a first portion having a first thickness and a second portion having a second thickness greater than the first thickness, at least one of at least a part of the feed element and at least a part of the director is provided on or inside the first portion, and at least a part of the feeder line is provided on or inside the second portion.