Dual-band loop antenna for thin mobile phones
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Solution Overview
Problem
Conventional dual-band mobile phone antennas face challenges in minimizing height while maintaining radiation efficiency, particularly when exposed to varying dielectric environments, such as being held by hand or near the head, leading to frequency shifts and decreased performance.
Innovation Solution
A dual-band loop antenna design featuring a ground plane, radiating metallic loop, and plate, printed on a dielectric substrate, generating multiple resonant modes to cover GSM and DCS bands with improved return loss and radiation patterns, reducing manufacturing costs and maintaining efficiency across frequency shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional dual-band planar inverted-F antenna is used, then the antenna can cover GSM and DCS bands, but the cell phone height increases to over 10 mm
Solution Approach 1:
The patent transitions from a three-dimensional planar inverted-F antenna structure to a two-dimensional printed loop antenna structure on a flat substrate. This dimensional change allows the antenna to maintain dual-band functionality while reducing the vertical height requirement, enabling integration into thin-profile mobile devices without compromising band coverage.
Solution Approach 2:
The patent replaces the mechanical planar inverted-F antenna structure with a printed loop antenna design that uses electromagnetic coupling between a radiating loop and a ground plane. This substitution eliminates the need for complex mechanical folding structures while achieving the same dual-band resonance through controlled electromagnetic field distribution.
2Length of stationary object
If a monopole antenna is used to minimize cell phone thickness, then the antenna is less affected by ground plane, but the antenna can cover only GSM band bandwidth
Solution Approach 1:
The printed loop antenna structure serves multiple functions simultaneously: it provides both GSM and DCS band coverage through its resonant modes, maintains thin-profile integration, and achieves stable radiation characteristics. The coupling between the radiating loop and ground plane enables dual-band operation without requiring separate antenna structures for each band.
Solution Approach 2:
The patent achieves dual-band coverage by carefully controlling geometric parameters of the loop antenna, including the loop dimensions, gap size, and distance between the radiating loop and ground plane. By optimizing these parameters, the antenna resonates at both GSM and DCS frequencies while maintaining a compact form factor suitable for thin devices.
3Volume of moving object
If conventional planar or monopole antennas are used in limited space, then the antenna structure is compact, but frequency shift occurs when held by hand or near head
Solution Approach 1:
The printed loop antenna structure acts as an intermediary between the limited internal space and the required radiation performance. The coupling mechanism between the radiating loop and ground plane provides stable electromagnetic field distribution that is less sensitive to external dielectric variations, maintaining reliable radiation efficiency even when the device is held by hand or near the head.
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 dual-band loop antenna achieves broadband performance with improved return loss and radiation characteristics, covering GSM and DCS bands effectively, meeting practical application requirements while minimizing phone thickness and maintaining efficiency in varying environments.
Implementation Method 1
generates a half-wavelength mode and a full-wavelength mode of a radiating metallic loop
Implementation Method 2
an additional half-wavelength mode by coupling between a radiating metallic plate thereof and the radiating metallic loop
Data Source
AI summary
A dual-band loop antenna for using in a mobile phone for (890˜960 MHz)/DCS(1710˜1880 MHz) application is disclosed to include a ground plane in a substantially rectangular shape having a grounding point and a shorting point, a radiating metallic loop having a feeding end and a shorting end electrically connected to the shorting point of the ground plane and spaced from the feeding end at a predetermined distance, and a radiating metallic plate surrounded by the radiating metallic loop and having one end electrically connected to a vicinity around the shorting end of the radiating metallic loop and spaced from the shorting end of the radiating metallic loop at a distance less than 10 mm.