Solar-Powered Vehicle ID Unit Antenna Layout for Wave Interference

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Solution Overview

Problem

Existing solar-powered onboard units for vehicle identification systems face challenges in optimizing wireless communication capabilities due to radio wave interference and power loss to the solar cell.

Innovation Solution

The onboard unit incorporates a patch antenna parallel to an electrically conductive layer of the solar cell, utilizing the solar cell as a reflector to redirect radio waves for improved antenna gain through constructive or destructive interference, enhancing communication efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the antenna is placed close to the solar cell for compact design, then device size is reduced, but radio wave interference occurs between the antenna and the electrically conductive layer of the solar cell

Engineering Contradiction:

Improvedevice sizeVSAvoidradio wave interference

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a dielectric layer as an intermediary between the antenna and the electrically conductive layer of the solar cell. This dielectric layer acts as a mediator that allows the antenna to be positioned close to the solar cell for compact design while preventing harmful radio wave interference through constructive interference of the electromagnetic waves.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical parameters of the system by specifying the distance between the antenna and the electrically conductive layer as an integer multiple of half the wavelength of the center frequency of the radio waves. This parameter adjustment ensures constructive interference, transforming potential harmful interference into beneficial signal reinforcement.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the electrically conductive layer of the solar cell is used as a reflector to improve antenna gain, then wireless communication performance is improved, but radio power is redirected away from the solar cell

Engineering Contradiction:

Improvewireless communication performanceVSAvoidpower to solar cell

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent converts the potentially harmful effect of radio wave reflection (which would normally cause interference and power loss) into a beneficial effect. By positioning the electrically conductive layer at a specific distance from the antenna, the reflected radio waves constructively interfere with the direct waves, enhancing antenna gain and improving wireless communication performance while the solar cell continues to function.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent applies different functional qualities to different parts of the system: the electrically conductive layer serves dual purposes as both a power-generating component (when illuminated) and a radio wave reflector (when positioned at the optimal distance from the antenna). This local differentiation of function allows the same component to serve multiple roles without compromising overall system performance.

Inventive Principle:

Principle #3Local quality

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 solution provides a solar-powered unit with improved radio communication by redirecting radio waves, increasing antenna gain in desired directions, thus optimizing wireless communication performance.

Implementation Method 1

the antenna is arranged at a distance from the electrically conductive layer of the solar cell such that radio waves penetrating the front side interfere at the antenna with radio waves reflected by the electrically conductive layer

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

radio waves penetrating the front side interfere at the antenna with radio waves reflected by the electrically conductive layer

Methodology Applied

Scientific EffectInterference: Interference

Implementation Method 3

a solar cell supported by the housing near the rear side, powering the circuit board and having a photosensitive side and an electrically conductive layer

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Data Source

PatentEP4456318B9Onboard unit for a wireless vehicle identification system

Publication Date: 2025.11.12 KAPSCH TRAFFICCOM AG

Figure 1~3

AI summary

An onboard unit (1) for wireless communication (2) with a vehicle identification system (3) via radio waves (W, W') comprises a housing (4) with a front side (5) and a rear side (6) and a circuit board (11) therein, an antenna (12) connected to the circuit board (11) and arranged in the housing (4) near the front side (5), and a solar cell (13) supported by the housing (4) near the rear side (6), powering the circuit board (11) and having a photosensitive side (15) and an electrically conductive layer (17), the photosensitive side (15) being visible from outside the housing (4), wherein the antenna (12) is arranged at a distance (D) from the electrically conductive layer (17) of the solar cell (13) such that radio waves (W) penetrating the front side (5) interfere at the antenna (12) with radio waves (W') reflected by the electrically conductive layer (17).