MIMO Bowtie Antenna Layout for Wideband Isolation in Thin Housings
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Solution Overview
Problem
Existing MIMO antenna devices struggle to maintain stable operation over a wide frequency band due to size constraints, leading to deterioration of voltage standing wave ratio (VSWR) and gain in the horizontal direction, as well as interference between antennas.
Innovation Solution
The antenna device incorporates a pair of first elements and a pair of second elements, with orthogonal polarized wave directions, where each element includes a portion acting as a self-similarity antenna or based on a similar operating principle, enabling the device to operate as a tapered-slot antenna at high frequencies, a loop antenna at low frequencies, and a dipole antenna in a middle frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna size (height) is decreased to make it low profile, then the antenna can be accommodated in a small area, but the voltage standing wave ratio (VSWR) deteriorates and gain in the horizontal direction becomes insufficient
Solution Approach 1:
The patent transitions from conventional planar antenna elements to three-dimensional tetrahedral elements, utilizing the third dimension (height/depth) to achieve broadband operation. The tetrahedral geometry with vertices at (0,0,0), (a,0,0), (0,b,0), and (0,0,c) creates a volumetric structure that maintains effective radiation and impedance characteristics across a wide frequency range while keeping the overall profile compact.
Solution Approach 2:
The patent employs parameter changes by varying the arm lengths (a, b, c) of the tetrahedral elements and adjusting the feed point positions to optimize performance across different frequency bands. The self-similarity principle is applied where the antenna structure maintains its geometric properties at different scales, enabling operation from 698 MHz to 6 GHz and beyond by scaling the electrical dimensions appropriately.
2Area of stationary object
If plural antennas are accommodated in a small area such as the shark fin antenna housing, then the device can be compact, but interference occurs between the antennas which adversely affects antenna characteristics
Solution Approach 1:
The patent uses asymmetric tetrahedral element orientations and positions within the housing to minimize mutual coupling and interference. By arranging the elements with different spatial orientations rather than symmetric configurations, the antenna system reduces harmful interactions while maintaining compact dimensions.
Solution Approach 2:
The patent introduces intermediate structures such as dielectric materials and ground plane configurations between the antenna elements to reduce interference. These intermediary elements act as shields or isolators that prevent direct coupling between adjacent antennas while allowing the compact housing design to be maintained.
3Adaptability or versatility
If the antenna is designed for wide frequency band operation, then the frequency range is expanded, but the isolation between antennas becomes difficult to satisfy over the wide frequency band
Solution Approach 1:
The patent achieves multi-functionality by designing the tetrahedral antenna elements to operate effectively across multiple frequency bands (698 MHz to 6 GHz and beyond) using the same basic structure. The self-similar geometry allows the antenna to maintain its radiation characteristics at different frequencies by scaling the electrical dimensions, providing universal performance across the wide frequency range without requiring multiple specialized antenna designs.
Solution Approach 2:
The patent employs dynamic impedance matching techniques where the feed point positions and element dimensions are optimized for different frequency ranges. The antenna system can adapt its electrical characteristics across the frequency band by adjusting the active elements, maintaining both wideband operation and adequate isolation through dynamic configuration changes.
Data Source
AI summary
A multiple-input multiple-output (MIMO) antenna device for spatial multiplexing transmission and that includes: a front side dipole antenna arranged on a front side surface; and a rear side dipole antenna arranged on a rear side surface which faces the front side surface. The front side dipole antenna and the rear side dipole antenna have a same frequency band. The front side dipole antenna includes a front side bowtie antenna, and the rear side dipole antenna includes a rear side bowtie antenna. The front side bowtie antenna or the rear side bowtie antenna includes, at a side surface defined between the front side surface and the rear side surface of the MIMO antenna device, a side surface element portion for adjusting antenna performance which extends from the front side bowtie antenna or the rear side bowtie antenna.