Antenna Stub with Varying Line Widths for Bandwidth
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Solution Overview
Problem
Conventional patch antennas face challenges in widening the communication frequency band and increasing antenna gain due to high Q values, which are restricted by the limited thickness of the antenna device, making it difficult to further reduce the Q value and expand the frequency range without increasing the overall thickness.
Innovation Solution
The antenna device incorporates a three-layer structure with a ground surface, an antenna surface, and a power supply surface, featuring a stub with series-connected transmission lines of varying widths and a bent portion, which decreases the Q value and increases bandwidth without increasing the antenna's overall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the overall thickness of the antenna device is increased to decrease the Q value and widen the communication frequency band, then the communication frequency band can be widened, but the device size increases which is not acceptable for mobile communication terminals
Solution Approach 1:
The patent changes the geometric parameters of the transmission lines in the stub structure, specifically varying the line widths of different transmission line segments. This parameter modification alters the impedance characteristics and resonance behavior, enabling Q value reduction and bandwidth widening without increasing the overall antenna thickness
Solution Approach 2:
The stub is divided into multiple transmission line segments with different line widths. By segmenting the transmission line and assigning different widths to different segments, the patent creates a complex impedance transformation path that reduces the Q value and widens the bandwidth while maintaining compact dimensions
2Adaptability or versatility
If the Q value is decreased to widen the communication frequency band, then the bandwidth increases, but this requires increasing the overall thickness of the antenna device
Solution Approach 1:
The patent modifies the geometric parameters of the transmission lines, specifically the line widths of different segments. By varying the line widths, the impedance characteristics are optimized to reduce the Q value and widen the bandwidth without requiring increased antenna thickness
Solution Approach 2:
The transmission lines in the stub are designed with asymmetric line widths, where different segments have different widths. This asymmetry creates specific impedance transformations that reduce the Q value and expand the bandwidth while maintaining a compact overall structure
3Adaptability or versatility
If conventional transmission lines with uniform width are used, then the structure is simple, but the Q value remains high and the bandwidth is limited
Solution Approach 1:
The patent changes the line width parameter of the transmission lines, creating segments with different widths. This parameter variation transforms the impedance characteristics and resonance behavior, reducing the Q value and widening the bandwidth
Solution Approach 2:
The patent introduces bent portions in the transmission lines, creating curved geometries instead of straight lines. These bent portions with varying line widths create complex electromagnetic field distributions that reduce the Q value and expand the bandwidth
Data Source
AI summary
An antenna device includes an antenna surface on which an antenna conductor is provided, a ground surface which is opposed to the antenna surface and on which a ground conductor is provided, and a stub configured by connecting, in series, a plurality of transmission lines in which a line width of at least a part of at least one transmission line is different from line widths of other two or more transmission lines. The at least one transmission line has straight portions and a bent portion.