Half-Wavelength Antenna Layout With Parasitic Reflector Directivity
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Solution Overview
Problem
Existing low-profile antenna devices face challenges in maintaining radiation efficiency and adjusting directivity due to their compact size, especially when accommodating multiple antennas in a narrow space, and existing solutions are not applicable to linearly polarized half-wavelength antennas.
Innovation Solution
A half-wavelength antenna device with a conductive plate, a half-wavelength element, and a parasitic element disposed in proximity and parallel to each other, electromagnetically coupled but insulated from the ground, allowing for adjustable directivity and compact size, with the parasitic element acting as a reflector to adjust the directivity pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the antenna height is reduced to 70 mm or less for low-profile design, then the design property and vehicle integration are improved, but radiation efficiency degrades due to antenna conductor loss
Solution Approach 1:
The patent changes the fundamental parameter of element length from quarter-wavelength to half-wavelength, which allows achieving the desired radiation efficiency in a more compact space. The half-wavelength element (length: 75-105 mm) maintains better current distribution and radiation characteristics compared to quarter-wavelength elements of the same physical length, thereby improving radiation efficiency while maintaining low profile.
Solution Approach 2:
The patent introduces a parasitic element disposed parallel to the driven element, creating a three-dimensional antenna structure. This spatial arrangement allows the antenna to achieve enhanced radiation efficiency through electromagnetic coupling between elements without increasing the overall height beyond 70 mm, effectively utilizing horizontal and depth dimensions to compensate for the reduced vertical dimension.
2Adaptability or versatility
If multiple antennas are accommodated in the narrow space of low-profile antenna device, then the composite antenna functionality is improved, but the distance between antennas cannot be ensured
Solution Approach 1:
The patent combines multiple antenna functions into a single integrated structure. The half-wavelength antenna device incorporates both the driven element and parasitic element in close proximity, creating a compact dual-element antenna that can be integrated with other antennas (TEL, GPS, V2X) in the limited space. The electromagnetic coupling between elements provides the necessary functionality without requiring large separation distances.
Solution Approach 2:
The patent employs a nested arrangement where the parasitic element is disposed in proximity and parallel to the driven element, with both elements insulated from the ground. This compact nested structure allows multiple antenna components to be accommodated in a small volume, enabling composite antenna functionality while maintaining the required electrical performance despite limited spacing.
3Ease of operation
If the parasitic element is disposed in proximity and parallel to the half-wavelength element, then the directivity adjustment capability is improved, but the device complexity increases
Solution Approach 1:
The parasitic element automatically adjusts the directivity pattern through electromagnetic coupling with the driven element, without requiring external control systems or complex adjustment mechanisms. The directivity control is achieved passively by the natural interaction between the two elements, simplifying the overall system while maintaining the desired directivity adjustment capability.
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 enables a small-sized antenna device capable of adjusting directivity while maintaining radiation efficiency, even in a low-profile form factor, allowing for effective accommodation of multiple antennas in limited spaces, such as a shark fin-shaped antenna design.
Implementation Method 1
a parasitic element disposed in proximity and parallel to the half-wavelength element so as to be electromagnetically coupled thereto but insulated from the ground
Data Source
AI summary
To provide a small-sized half-wavelength antenna device capable of adjusting directivity. A half-wavelength antenna device for a vehicle includes: a conductive plate 10; a half-wavelength element 20; and a parasitic element 30. The conductive plate 10 has a feeding part 11 and a ground 12. The half-wavelength element 20 is vertically installed on the conductive plate 10 so as to be connected to the feeding part 11 but insulated from the ground 12. The parasitic element 30 is disposed in proximity and parallel to the half-wavelength element 20 so as to be electromagnetically coupled thereto but insulated from the ground 12.