Spatially Diverse Antennas for Headset RF Shadowing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless communication devices face challenges in maintaining effective RF signal coverage due to RF shadowing caused by the user's head, particularly in environments with multipath propagation, leading to reduced antenna performance and limited coverage in line-of-sight and shadow regions.
Innovation Solution
A headset computing device with spatially diverse antennas, arranged approximately 180° apart to form a combined radiation pattern approaching omnidirectional coverage, including dual linear polarization, and equipped with a splitter/combiner and RF switch to enhance signal transmission and reception, reducing RF losses and improving communication links across multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single antenna is used in a headset device, then the device structure remains simple, but RF signal coverage is limited due to head shadowing and multipath propagation
Solution Approach 1:
The patent divides the antenna system into multiple spatially separated antenna elements (typically two or more antennas positioned at different locations on the headset frame). This segmentation allows each antenna to capture signals from different spatial paths, overcoming the limitations of single-antenna systems where the user's head blocks line-of-sight paths and creates RF shadow regions.
Solution Approach 2:
The patent transitions from a single-point antenna configuration to a spatially distributed antenna array. By adding the spatial dimension (positioning antennas at different locations around the user's head), the system can receive signals from multiple directions simultaneously, converting a 0D single-antenna problem into a 1D or 2D spatial diversity system that maintains coverage despite head movement and orientation changes.
2Reliability
If multiple antennas are positioned to provide omnidirectional coverage, then RF signal coverage improves, but the headset profile height increases
Solution Approach 1:
The patent positions antenna elements at specific locations on the headset frame where they can achieve optimal radiation patterns for their local environment. Rather than requiring uniform omnidirectional coverage from a single high point, each antenna is strategically placed to cover specific angular sectors, and their combined patterns provide overall omnidirectional coverage while maintaining a low profile.
Solution Approach 2:
The patent achieves omnidirectional coverage not by increasing vertical height but by distributing antennas horizontally around the headset frame. This spatial redistribution in the horizontal plane (adding lateral separation rather than vertical elevation) allows the system to maintain a low-profile design while achieving 360-degree coverage through the combined radiation patterns of multiple antennas positioned at different azimuthal angles.
3Reliability
If antennas are placed in RF shadow regions, then coverage in those regions improves, but line-of-sight signal strength decreases
Solution Approach 1:
The patent segments the coverage responsibility between different antenna elements based on their spatial positions relative to the user's head. Antennas positioned on opposite sides of the head each cover different angular sectors, with one antenna optimally positioned to capture line-of-sight signals while another is positioned to receive signals from RF shadow regions through reflected or diffracted paths.
Solution Approach 2:
The patent uses multiple antennas as intermediary receivers that capture signals through different propagation paths. When the user's head blocks direct line-of-sight paths, other antennas positioned in different spatial locations act as intermediaries that can receive signals via reflected paths off surrounding surfaces or diffracted paths around the head, thereby maintaining communication links in shadow regions without sacrificing line-of-sight performance.
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 spatially diverse antenna system significantly improves RF signal coverage and communication performance by maintaining effective radiation patterns in both line-of-sight and shadow regions, enhancing mobility and reliability in various environments, including those with multipath propagation.
Implementation Method 1
The transmit antenna converts the modulated signal from a signal propagating along a transmission line into a signal propagating through free space
Implementation Method 2
the user's head creating a radiofrequency (RF) shadow region along the headset profile by blocking line-of-sight RF propagation paths
Data Source
AI summary
The invention presented relates to wireless handsfree head worn headset computing devices including a microdisplay device and spatially diverse antenna system. The spatially diverse antenna system provides an effective headset computing device radiation pattern that enables arbitrary user movement and promotes freedom of mobility. Disclosed is a headset computing device including a head worn frame having a profile relatively low in height with respect to a user's head, the user's head creating a RF shadow region along the headset profile by blocking line-of-sight RF propagation paths, the headset includes two or more antennas integrated with the headset frame to sufficiently maintained its low profile. Each antenna has a radiation pattern and are collectively arranged to form an omnidirectional radiation pattern, where at least a first radiation pattern provides coverage in the line-of-sight propagation path while the at least second radiation antenna pattern is in the RF shadow region.