Circular Polarized Multipart Antenna for Vehicle Access
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Solution Overview
Problem
Existing antenna arrangements in motor vehicle access systems face challenges with linear polarization, leading to unreliable radio signal transmission due to body effects and variable polarization orientations between mobile and on-board stations, resulting in communication failures even with sufficient transmission power.
Innovation Solution
An antenna apparatus comprising two non-closed conductor loop branches arranged perpendicularly to each other, creating a circular-polarized radiation and reception characteristic, which reduces body effects and maintains reliable communication regardless of alignment, suitable for compact mobile devices like motor vehicle keys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear polarization is used in antenna arrangements, then the antenna structure is simple, but reliable radio signal transmission cannot be ensured due to body effects and variable polarization orientations
Solution Approach 1:
The patent combines two linearly polarized antenna elements (first and second antenna branches) with orthogonal polarizations into a single antenna arrangement. By feeding these elements with a 90-degree phase difference, the system merges their radiation patterns to produce circular polarization, thereby improving transmission reliability across varying orientations while maintaining a compact structure suitable for mobile devices.
Solution Approach 2:
The antenna arrangement dynamically adapts to different spatial orientations by utilizing circular polarization. Unlike fixed linear polarization that degrades when misaligned, the circularly polarized antenna maintains consistent performance regardless of the relative orientation between transmitting and receiving antennas, effectively making the radiation characteristic adaptive to dynamic usage conditions.
2Reliability
If loop antennas are used to reduce body effect, then body effect is reduced, but radiation efficiency is low and only linear polarization is achieved
Solution Approach 1:
The patent merges two loop antenna elements with orthogonal orientations into a single arrangement. The first antenna branch provides one linear polarization component while the second antenna branch provides the orthogonal component. By combining these elements with appropriate phase shifting, the system achieves circular polarization that maintains the low body effect advantage of loop antennas while improving radiation efficiency through the combined radiation patterns.
Solution Approach 2:
The antenna arrangement uses a composite structure combining two different loop antenna configurations (first and second antenna branches with different orientations) to create a system with superior properties. This composite approach allows the antenna to benefit from the low body effect of loop structures while achieving the higher radiation efficiency and circular polarization characteristics needed for reliable communication.
3Loss of energy
If monopole antennas are used to improve radiation efficiency, then efficiency is improved, but body effect increases and only one polarization direction is supported
Solution Approach 1:
The patent combines two monopole-like antenna branches with orthogonal polarizations into a single arrangement. By feeding these branches with a 90-degree phase difference, the system merges their individual radiation patterns to produce circular polarization. This approach maintains the high radiation efficiency of monopole structures while reducing body effect through the orthogonal combination and circular polarization characteristic.
4Loss of energy
If antenna polarization is fixed for optimal transmission, then transmission efficiency is maximized, but communication fails when polarization directions are misaligned between stations
Solution Approach 1:
The antenna arrangement dynamically adapts to different spatial orientations by utilizing circular polarization. Unlike fixed linear polarization that degrades when misaligned, the circularly polarized antenna maintains consistent performance regardless of the relative orientation between transmitting and receiving antennas. The time-varying electric field vector of circular polarization ensures that at least one component is always aligned with the receiving antenna, providing robust communication across all orientations.
Solution Approach 2:
The circularly polarized antenna arrangement functions universally across all polarization orientations. A single antenna design can effectively communicate with other antennas regardless of their specific orientation in space, eliminating the need for precise alignment or multiple antenna elements oriented in different directions. This universal compatibility makes the system adaptable to various usage scenarios and device orientations.
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 antenna apparatus ensures reliable radio connections with low body effect and isotropic radiation, allowing communication over varying distances and orientations, enhancing the efficiency and range of radio-based access systems.
Implementation Method 1
The antenna apparatus ensures reliable radio connections with low body effect and isotropic radiation
Implementation Method 2
creating a circular-polarized radiation and reception characteristic
Data Source
AI summary
An antenna apparatus has a first antenna branch and a second antenna branch. Both the first and the second antenna branch are in the form of a conductor loop which is not closed, and the first antenna branch is arranged at a distance from the second antenna branch in a direction which is substantially at right angles to the surface bounded by the respective conductor loop, such that the first loop direction, which is defined from the foot point to the free end of the first antenna branch, is arranged in the opposite direction to the second loop direction, which is defined from the foot point to the free end of the second antenna branch.