Capacitive PCB Antenna Layout for Compact Wideband Mobile Terminals
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Solution Overview
Problem
Existing mobile terminal antennas face challenges in miniaturization and broadbandization, struggling to cover both low and wide frequency bands within a small-sized space, as their electrical length needs to be at least a quarter to a half of the low-frequency wavelength to produce both low-frequency and wide-frequency resonance frequencies.
Innovation Solution
The design incorporates a first radiator and a first capacitor structure, where the first end is connected to a signal feed end and the second end to a ground end of a printed circuit board, with an electrical length greater than one eighth but less than a quarter of the wavelength, allowing for multiple resonance frequencies to be produced within a compact space, and optionally includes a second radiator and parasitic branch for further frequency coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the electrical length of the antenna is increased to at least a quarter to a half of the low-frequency wavelength to produce both low-frequency and wide-frequency resonance frequencies, then the frequency coverage is improved, but the antenna size increases and cannot be miniaturized
Solution Approach 1:
The patent changes the electrical length parameter of the radiator to be between one eighth and a quarter of the low-frequency wavelength, which is shorter than conventional designs. This parameter change enables the antenna to produce multiple resonance frequencies including low-frequency and wide-frequency bands while maintaining a compact size, thus resolving the contradiction between frequency coverage and antenna size
Solution Approach 2:
The patent divides the antenna system into multiple functional components including a first radiator, a second radiator, a parasitic branch, and a capacitor structure. Each segment contributes to different resonance frequencies, allowing the overall system to achieve broad frequency coverage without requiring each individual component to be large, thus enabling miniaturization while maintaining versatility
2Volume of moving object
If the antenna size is reduced to meet compact mobile terminal design requirements, then the device compactness is improved, but the ability to cover both low and wide frequency bands deteriorates
Solution Approach 1:
The patent employs a nested structure where the second radiator is positioned within or alongside the first radiator, and the parasitic branch is integrated into the overall structure. This nesting allows multiple radiating elements to occupy reduced space while each element contributes to different frequency bands, achieving both compactness and broad frequency coverage
Solution Approach 2:
The patent designs the antenna system where a single integrated structure performs multiple functions: the first radiator produces low-frequency resonance, the second radiator produces wide-frequency resonance, and the parasitic branch contributes additional resonance frequencies. This multi-functionality allows the antenna to cover both low and wide frequency bands within a compact volume
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 enables the production of multiple resonance frequencies within a small space, effectively covering a wide frequency range from 791 MHz to 2800 MHz, enhancing the antenna's performance and bandwidth in mobile terminals.
Implementation Method 1
a first end of the first radiator is electrically connected to a signal feed end of a printed circuit board by means of the first capacitor structure
Implementation Method 2
the first radiator, the first capacitor structure, the signal feed end, and the ground end form a first antenna configured to produce a first resonance frequency
Data Source
AI summary
An antenna includes a first radiator and a first capacitor structure. A first end of the first radiator is electrically connected to a signal feed end of a printed circuit board by means of the first capacitor structure, and a second end of the first radiator is electrically connected to a ground end of the printed circuit board. The first radiator, the first capacitor structure, the signal feed end, and the ground end form a first antenna configured to produce a first resonance frequency. An electrical length of the first radiator is greater than one eighth of a wavelength corresponding to the first resonance frequency, and the electrical length of the first radiator is less than a quarter of the wavelength corresponding to the first resonance frequency.