3D Folded Monopole Antenna for MIMO Mode Isolation
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Solution Overview
Problem
Mobile wireless communication devices face challenges in accommodating multiple frequency bands due to physical limitations, leading to coupling and mode isolation issues with multiple antennas in close proximity, which disrupts MIMO performance and makes it difficult to achieve high performance and compact size simultaneously.
Innovation Solution
A multi-band three-dimensional (3D) folded monopole antenna design with high mode isolation, featuring a pair of monopole antenna elements formed of conductive metallic traces folded into a 3D structure, allowing independent adjustment of operational frequency bands and minimizing coupling between radiation elements, thereby enabling efficient coverage of various communication frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple antennas are used to cover multiple frequency bands, then bandwidth coverage is improved, but coupling and mode isolation problems occur due to limited space
Solution Approach 1:
The patent transitions from planar 2D antenna elements to three-dimensional folded monopole structures. The antenna elements are folded along multiple axes to create a 3D configuration that achieves superior mode isolation and bandwidth performance within the constrained mobile device form factor, resolving the contradiction between compact size and multiple frequency band coverage
2Adaptability or versatility
If antenna size is increased to achieve lower resonant frequency bands, then frequency band coverage is improved, but device size increases
Solution Approach 1:
The folded monopole antenna utilizes three-dimensional folding to achieve quarter-wavelength resonance at lower frequencies without requiring proportionally larger planar dimensions. The 3D folded structure effectively packs the required electrical length into a compact physical volume, maintaining mobile device size constraints while extending coverage to lower frequency bands
Solution Approach 2:
The antenna elements are folded back on themselves in a nested configuration, where portions of the antenna structure are contained within or adjacent to other portions. This nested folding achieves the required electrical length for lower frequency resonance while minimizing the overall bounding box volume of the antenna assembly
3Adaptability or versatility
If additional parasitic branches are used to enhance bandwidth, then frequency band coverage is improved, but volume and higher-mode coupling increase
Solution Approach 1:
Instead of adding more parasitic branches in the planar direction, the patent achieves bandwidth enhancement through the third dimension by folding the monopole elements in 3D space. This vertical/folded dimensionality provides additional degrees of freedom for impedance matching and bandwidth control without increasing the antenna's planar footprint or overall 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
The design achieves high mode isolation and efficient coverage of multiple frequency bands, including GSM, UMTS, GPS, and LTE, with improved antenna performance and compact size, allowing for flexible adjustment of resonant frequencies and reduced coupling, enhancing MIMO performance in mobile devices.
Implementation Method 1
a first monopole for radiating at a first resonant frequency, and a second monopole for radiating at a second resonant frequency
Data Source
AI summary
A multi-band antenna comprising a dielectric substrate, a ground plane formed on a first area of the dielectric substrate, a radiation part arranged in a second area of the dielectric substrate where the ground surface is not formed, a feed section formed of a metallic trace and having one end connected to the radiation part and an opposite end disposed near an edge of the ground plane for forming a feed point and the radiation part having a pair of monopole antenna elements formed of conductive metallic traces; a first monopole antenna element for radiating at a first resonant frequency, and a second monopole antenna element for radiating at a second resonant frequency and the conductive metallic traces being folded to form a three dimensional structure, with at least a portion of said first monopole spaced from a plane of the substrate and said second monopole.