Railway Antenna Using Photonic Band Gap Arrays
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Solution Overview
Problem
Existing antennas on railway vehicles are limited to communicating over short distances, requiring frequent stations along railway tracks, and increasing range with standard designs would necessitate large and heavy antennas, which is impractical.
Innovation Solution
A lightweight, low-cost antenna utilizing a Wavelet Photonic Band Gap (PBG) structure with an array of dipoles and directors, employing a beam forming algorithm for efficient energy coupling and surface wave reduction, enabling communication over hundreds of miles while maintaining a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the distance between stations is increased to decrease the number of stations, then the communication distance requirement increases, but the antenna size and weight would become impractically large with standard Yagi designs
Solution Approach 1:
The patent changes the operating frequency parameter from conventional VHF/UHF bands to L-band (1-2 GHz), which allows for shorter antenna elements while achieving extended communication ranges of 100-200 miles through optimized radiation patterns and gain characteristics
Solution Approach 2:
The antenna employs a composite structure combining multiple dipole elements arranged in specific geometric configurations with reflective surfaces and director elements, creating a composite antenna system that achieves high gain and extended range without proportionally increasing size
2Length of stationary object
If the antenna size is increased to extend communication range with standard Yagi design, then the communication distance improves, but the weight increases to several thousand pounds which is not practical
Solution Approach 1:
By transitioning to L-band frequencies and optimizing the antenna geometry with compact dipole arrangements, the patent achieves 100-200 mile communication ranges with antennas weighing only tens of pounds, compared to thousands of pounds required for conventional designs
Solution Approach 2:
The antenna is divided into multiple discrete dipole elements, reflectors, and directors that can be independently optimized and arranged in space, allowing the system to achieve high gain through spatial distribution rather than simply scaling up single-element size
3Length of stationary object
If conventional Yagi antennas are used to achieve extended range, then the communication distance may improve, but the bandwidth and gain performance deteriorates
Solution Approach 1:
The patent employs a composite antenna structure with multiple dipole elements operating in coordinated fashion, where the combination of different element types (dipoles, directors, reflectors) creates a system with both extended range and enhanced bandwidth characteristics
Solution Approach 2:
The antenna design integrates multiple functional elements within a single structure that simultaneously provides wide bandwidth operation, high gain in specific directions, and extended communication range, making the system versatile for multiple rail communication applications
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 achieves a ten-fold increase in communication range with improved bandwidth and gain, reducing the need for frequent stations and allowing for efficient data transmission over extended distances with minimal size and weight increments.
Implementation Method 1
couples the energy emitted by adjacent radiator elements contributing to a more efficient and stronger wave front energy
Implementation Method 2
This coupled energy is summed and launched to aid in the construction of a resultant beam based on a beam forming algorithm
Implementation Method 3
The PBG structure of the antenna comprises, in a manner per se known, several substrate layers (not shown in the figure) including Teflon, Arlon and Rohacell HF-71 foam. These substrate layers represent altogether the low dielectric properties material cited here above.
Implementation Method 4
The antenna of the present invention is based on an array structure which creates a longer wave front in the propagation space, starting from an original smaller wave front (higher excitation frequency).
Data Source
AI summary
Antenna (1) for railway vehicles comprising:a plurality of photonic band gaps PGB cells (2), placed adjacent each other and made of a layer of low dielectric properties material placed on a metal ground plane (4), wherein each photonic band gap cell (2) form a reflector (6) of the antenna (1);a plurality of first metallic bars (8), placed on top of the PBG cells (2);a plurality of second metallic bars (10), each embedded, at least partially, in the thickness of the low dielectric properties material;wherein the second metallic bars (10) are each roughly perpendicular to the respective reflector (6).