Modified BiQuad Antenna for V2X
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Solution Overview
Problem
Traditional BiQuad antennas have high impedance mismatch with 50 Ohm coaxial cables, deep nulls in side directions, and a bulky design, making them unsuitable for high-efficiency and compact Vehicle-to-Everything (V2X) communications, particularly for DSRC protocols used in truck platooning.
Innovation Solution
A modified BiQuad antenna system with a radiating element comprising straight segments forming two connected quadrilateral frame antennas over a planar reflector, where inner segments are parallel to the reflector and outer segments are inclined, reducing side nulls and impedance mismatch, and integrated with a feeding line for a compact and self-grounded structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional BiQuad antenna is used, then vertical polarization and self-grounding properties are achieved, but impedance mismatch with 50 Ohm coaxial cables occurs and the structure becomes bulky
Solution Approach 1:
The patent modifies the geometric parameters of the quadrilateral frame segments, specifically making the outer segments longer than the inner segments and inclining the outer segments relative to the reflector. This parameter change transforms the impedance from the traditional high value (around 75 Ohms) to a matched value with 50 Ohm coaxial cables, while simultaneously reducing the overall structure height to achieve a compact design.
Solution Approach 2:
The patent introduces a three-dimensional configuration by inclining the outer segments of the quadrilateral frame relative to the reflector plane, creating a non-planar structure. This dimensional change allows the antenna to achieve both impedance matching and compactness while maintaining the self-grounding property through the vertical orientation of the radiating elements.
2Device complexity
If a classical BiQuad antenna configuration is used, then the antenna structure is simple, but deep nulls appear in side directions which is unsuitable for DSRC applications
Solution Approach 1:
The patent applies asymmetry by making the outer segments of the quadrilateral frame longer than the inner segments, and by inclining the outer segments at a specific angle relative to the reflector. This asymmetric configuration redistributes the radiation pattern, reducing the deep nulls in side directions that characterize traditional BiQuad antennas, while maintaining overall structural simplicity.
3Length of stationary object
If the antenna height is reduced for compact design, then the thin profile is achieved, but impedance matching and radiation efficiency may be compromised
Solution Approach 1:
The patent achieves compactness by reducing the antenna height to approximately 1/3 of the wavelength, which is significantly shorter than traditional BiQuad antennas. This is accomplished through parameter changes in the segment lengths and inclination angles, which simultaneously maintain proper impedance matching to 50 Ohm cables and ensure radiation efficiency through optimized current distribution on the shortened structure.
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 system achieves high efficiency, directivity, and a thin profile, with reduced side nulls and impedance matching to 50 Ohms, enabling reliable V2X communications with improved radiation patterns for truck platooning applications.
Implementation Method 1
the radiating element comprises segments, arranged to configure a BiQuad formed by two connected quadrilateral frame antenna elements
Implementation Method 2
The reflector is planar... with relatively high directivity in front and rear directions
Data Source
Figure 1A~1B
Figure 1C~1E
Figure 1F~2A
AI summary
The invention refers to an antenna system vehicles, preferably for Vehicle-to-Everything (V2X) communications, comprising a planar reflector and a radiating element placed over the reflector, wherein the radiating element comprises segments, preferably straight segments, arranged to configure two connected quadrilateral frame antenna elements. Each quadrilateral frame antenna element having an inner pair of segments and an outer pair of segments, wherein the segments of the inner pairs are substantially parallel to the reflector, and the segments of the outer pairs are inclined with respect to the segments of the inner pairs. The segments of the outer pairs have one end connected with the reflector.