Orthogonal MIMO Antenna Layout for Wideband Isolation
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Solution Overview
Problem
Conventional MIMO antenna devices face challenges in achieving stable operation over a wide frequency band and reducing interference between antennas, particularly in compact designs, leading to deteriorated voltage standing wave ratio (VSWR) and gain in the horizontal direction.
Innovation Solution
The antenna device incorporates a pair of first elements and a pair of second elements with orthogonal polarized wave directions, each featuring self-similarity antenna structures such as biconical or bow-tie antennas, arranged in a configuration that reduces interference and expands the frequency band operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the unbalanced antenna is made low profile to reduce antenna size, then the antenna height decreases, 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 self-similarity antenna structures with radial and axial components. The antenna elements extend in multiple dimensions with varying cross-sectional shapes along their length, enabling compact height while maintaining effective radiating area and impedance matching across wide frequency bands.
Solution Approach 2:
The patent employs self-similarity antenna structures where the cross-sectional shape and dimensions vary continuously along the length of the antenna element. This parameter variation enables the antenna to maintain consistent electrical characteristics and impedance matching across a wide frequency range while keeping the overall height compact.
2Area of stationary object
If multiple antennas are accommodated in a small area to reduce device size, then the antenna housing dimensions decrease, but interference occurs between antennas affecting antenna characteristics
Solution Approach 1:
The patent assigns different polarization orientations to different antenna elements within the compact housing. By making each antenna element have distinct local characteristics (different polarization directions), the patent enables multiple antennas to coexist in a small area with reduced mutual interference, as each element operates in its own electromagnetic field orientation.
Data Source
AI summary
An antenna device includes: a pair of first elements that are arranged on a first plane; and a pair of second elements that are arranged on a second plane parallel to the first plane such that a polarized wave direction of the pair of second elements is orthogonal to that of the pair of first elements. Each element of the pair of first elements and the pair of second elements includes a portion that acts as a self-similarity antenna or an antenna that acts based on similar operating principle to the self-similarity antenna. In one embodiment, each element of the pair of first elements and the pair of second elements includes two arms that extend in a direction away from each other from a proximal end portion to which a feed point is connectable.