Dipole Antenna for Safety Helmets with Extended Arms
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Solution Overview
Problem
Substantially-linear dipole antennas in safety helmets, particularly at 2.4 - 2.5 GHz frequencies, suffer from reduced reception and transmission range due to interference from the user's head and neck, limiting their omnidirectionality and effectiveness.
Innovation Solution
The design incorporates two conductive branches, each 1/4 of the operative wavelength long, with additional 1/2 wavelength arms extending from them, connected by chokes to avoid impedance issues, and printed onto a circuit board for easy installation under the helmet's outer cap, allowing the antenna to surround the head and neck without being excessively shielded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a substantially-linear dipole antenna with two 1/4 wavelength branches is used, then the antenna size is reduced and can be easily adapted to the helmet shape, but the reception/transmission range is reduced due to interference from the user's head and neck
Solution Approach 1:
The antenna is divided into two functional segments: two 1/4 wavelength conductive branches for compact integration into the helmet, and two 1/2 wavelength conductive arms extending outward for maintaining reception/transmission range. This segmentation allows each part to fulfill its specific function optimally.
Solution Approach 2:
The antenna design transitions from a compact 3D configuration (branches close to the head) to an extended linear configuration (arms reaching outward), effectively using spatial dimensionality to overcome the shielding effect of the head and neck while maintaining omnidirectionality.
2Ease of manufacture
If the dipole antenna is positioned in a central, back and bottom region of the helmet, then constructive convenience and bulk requirements are satisfied, but signal absorption by the human body significantly reduces the operative range
Solution Approach 1:
The conductive arms act as intermediaries that extend the antenna's effective radiating elements away from the body, mediating between the compact internal antenna structure and the external electromagnetic environment, thereby reducing signal absorption by the human body.
3Reliability
If the dipole antenna is extended to surround the head and neck, then omnidirectionality and reception range are improved, but the antenna complexity and installation difficulty increase
Solution Approach 1:
The antenna design merges the compact 1/4 wavelength branches with the extended 1/2 wavelength arms into a single integrated dipole structure, achieving both omnidirectionality and extended range without requiring multiple separate antenna elements or complex mounting mechanisms.
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
This configuration enhances omnidirectionality and significantly increases the radio signal range by minimizing shielding from the user's head and neck, while being easily integrated into the helmet's structure.
Implementation Method 1
the transmission and reception of radio signals in a safety helmet is particularly popular for the optimal omnidirectionality features shown by such type of antennas
Implementation Method 2
the maximum signal absorption at such frequency band is given by water and therefore by the human body
Data Source
AI summary
Substantially-linear dipole antenna (100) for safety helmets (1), of the type comprising two conductive branches (3) arranged to be electrically connected, at one of their ends, to a respective radio equipment (4), the two conductive branches being disposed substantially aligned. The two conductive branches (3) have a length essentially equal to 1/4 of the expected operative wavelength of the radio equipment (4). The dipole antenna (100) further comprises at least two conductive arms (8), each having a length essentially equal to 1/2 of said operative wavelength, each of which is electrically connected respectively to the free end of both of the two conductive branches (3), both having a length essentially equal to 1/4 of the operative wavelength.