Antenna Device Common Feed Point Resonance Suppression
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Solution Overview
Problem
Existing antenna devices face efficiency deterioration in the high band due to unnecessary resonance of the low-band antenna element when connected to a common feed point with high-band antenna elements, leading to loss and reduced performance.
Innovation Solution
Incorporating an antenna-shortening inductor connected in parallel with a capacitor between the low-band antenna element and the feed point, which shifts the ¾ wavelength resonance frequency of the low-band antenna element above the high band, reducing loss and enhancing efficiency by allowing high-band current to pass through both the inductor and capacitor, and optionally using a ground conductor to increase radiation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a low-band antenna element and high-band antenna element are connected to a common feed point, then the antenna device can operate in multiple bands, but the low-band antenna element is excited by 3/4 wavelength resonance in the high band causing loss and efficiency deterioration
Solution Approach 1:
A matching circuit is inserted between the common feed point and the low-band antenna element to act as an intermediary that prevents 3/4 wavelength resonance excitation in the high band while maintaining multi-band operation capability
Solution Approach 2:
The matching circuit changes the impedance parameters and resonance characteristics of the low-band antenna element to suppress unwanted 3/4 wavelength resonance in the high band, thereby reducing energy loss and improving antenna efficiency
2Adaptability or versatility
If the low-band antenna element is designed for low band operation, then it achieves low band coverage, but it causes unnecessary resonance in the high band when connected to common feed point
Solution Approach 1:
The matching circuit serves as a mediator between the feed point and low-band antenna element, filtering out high-band frequencies that would cause 3/4 wavelength resonance while allowing low-band operation
Solution Approach 2:
The matching circuit extracts or removes the harmful 3/4 wavelength resonance component from the low-band antenna element's response in the high band, allowing the antenna to maintain low-band coverage without generating unnecessary resonance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration suppresses unnecessary resonance of the low-band antenna element in the high band, reducing loss and improving antenna efficiency by ensuring high-band current flows through the inductor and capacitor, thereby preventing efficiency deterioration and enhancing radiation performance.
Implementation Method 1
a capacitor that is connected to the antenna-shortening inductor in parallel
Implementation Method 2
an inductor for shortening the antenna element (hereinafter, 'antenna-shortening inductor') that is connected to between the low-band antenna element and the feed point
Implementation Method 3
a parallel circuit of the inductor and the capacitor is capacitive in a high band, and a frequency of 3/4 wavelength resonance of the low-band antenna element can be made higher than the high band
Data Source
AI summary
In an antenna device including a high-band antenna element and a low-band antenna element that are connected to a common feed point and feeding electric power using one feed point, influence by unnecessary resonance of the low-band antenna element in a high band is suppressed. The antenna device includes a high-band antenna element and a low-band antenna element that are connected to a common feed point, an antenna-shortening inductor that is connected to between the low-band antenna element and the feed point, and a capacitor that is connected to the antenna-shortening inductor in parallel.