Notch Antenna Reactance Circuit Multiband Miniaturization
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Solution Overview
Problem
Existing notch antennas face challenges in miniaturization and efficiency, particularly in achieving multi-resonance across various frequency bands without compromising size or increasing match loss, due to limitations in slit length and Q factor adjustments.
Innovation Solution
A one-slit notch antenna with a reactance circuit providing capacitive reactance at the open end, allowing for multi-resonance characteristics by bridging the slit and connecting to the ground conductor, and using a variable capacitor to adjust resonant frequencies without altering the physical shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple slits are formed in the ground plate to achieve multiband operation, then the antenna can operate in multiple frequency bands, but the antenna cannot be miniaturized
Solution Approach 1:
The invention divides the single slit into multiple segments by introducing reactive elements (capacitors or inductors) at specific positions along the slit. These reactive elements effectively segment the continuous slit into multiple functional sections, each contributing to different resonant frequencies, thereby achieving multiband operation without requiring multiple separate slits
Solution Approach 2:
The invention changes the electrical parameters (reactance values) at different positions along the slit to create multiple resonant frequencies. By adjusting the reactance values of capacitors or inductors placed at specific locations, the antenna achieves multiband operation while maintaining a compact physical structure
2Volume of moving object
If the slit length is reduced to miniaturize the antenna, then the antenna size is reduced, but the antenna efficiency decreases
Solution Approach 1:
The invention changes the electrical characteristics of the shortened slit by introducing reactive elements that electrically extend the effective length of the slit. This allows the physical slit to be shorter while maintaining the electrical performance equivalent to a longer slit, thereby preserving antenna efficiency in a miniaturized structure
Solution Approach 2:
The reactive elements (capacitors or inductors) act as intermediaries that compensate for the reduced slit length. These elements store and release electromagnetic energy, effectively extending the electrical path length without increasing the physical dimensions, thus maintaining antenna efficiency in a compact form
3Adaptability or versatility
If a parallel resonant circuit is inserted to achieve broadband characteristics, then double resonance characteristics are obtained, but the match loss increases due to capacitor resistance
Solution Approach 1:
The invention changes from using parallel resonant circuits with capacitors to using series resonant circuits with inductors, or alternatively uses capacitors with opposite polarity orientation. This parameter change in the circuit configuration reduces the impact of resistive losses while maintaining the broadband and multiband resonant characteristics
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
The solution enables efficient operation across multiple frequency bands with high antenna efficiency, maintaining a compact size and adaptable to different communication systems and frequency drifts, while minimizing match loss and bandwidth narrowing.
Implementation Method 1
a reactance circuit (17) having capacitive reactance in at least two frequency bands
Implementation Method 2
producing resonance in a plurality of frequency bands
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3B
AI summary
A notch antenna includes a ground conductor having a slit and a reactance circuit containing a capacitive reactance element and an inductive reactance element, the reactance circuit being placed at an open end of the slit so as to bridge the slit and being connected to the ground conductor. The slit has a closed end to which power is supplied, and the capacitance of the capacitive reactance element and the inductance of the inductive reactance element are set so that the reactance circuit has a capacitance desired to obtain a first antenna resonance point at a first frequency and a capacitance desired to obtain a second antenna resonance point at a second frequency.