Vehicle Radar PCB Wave Termination via Multi-Layer Substrate
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Solution Overview
Problem
Existing radar systems for vehicles face challenges in designing a cost-effective and simple wave termination that minimizes signal reflections, as current solutions like absorber mats and separate wave termination components are expensive and require additional space or are unsuitable for high-frequency applications.
Innovation Solution
A multi-layer circuit board design with a low-loss first substrate layer and a high-loss second substrate layer, where the wave termination leads the signal from the low-loss layer to the high-loss layer, achieving attenuation and absorption without additional components, using a substrate integrated waveguide and a microstrip conductor configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an absorber mat made of high-loss material is placed at the end of the conductor to achieve wave termination, then signal reflection is minimized, but manufacturing cost increases and additional process steps are required
Solution Approach 1:
The wave termination function is merged with the existing substrate structure by creating a through-hole that penetrates the substrate and connecting conductive layers. This eliminates the need for separate absorber mats while achieving the same signal termination effect through the inherent resistive properties of the conductive paths and substrate material.
Solution Approach 2:
The substrate and its conductive layers serve the dual purpose of structural support and signal termination. The through-hole configuration with conductive connections creates an inherent wave termination mechanism that does not require additional components or materials, allowing the circuit board itself to provide the termination function.
2Reliability
If a separate wave termination component is soldered onto the cable end to achieve impedance matching, then signal reflection is reduced, but component cost increases and frequency range is limited
Solution Approach 1:
The wave termination functionality is integrated directly into the circuit board structure through through-holes that connect multiple conductive layers. This eliminates the need for separate termination components while achieving impedance matching through the distributed capacitive and resistive effects of the layered conductive structure.
Solution Approach 2:
The through-hole structure serves multiple functions simultaneously: it provides mechanical support, electrical connection between layers, and wave termination through its resistive and capacive properties. This multi-functional design works across a broad frequency range without requiring frequency-specific components.
3Loss of energy
If an antenna is used as wave termination to radiate the signal, then signal absorption is achieved, but interference with other radar antennas occurs
Solution Approach 1:
Instead of radiating the terminated signal as with an antenna, the energy is converted into heat through resistive dissipation in the conductive paths and substrate. This converts the potentially harmful radiated energy into harmless thermal energy, eliminating interference while maintaining effective signal termination.
Solution Approach 2:
The substrate and conductive layers serve as both the transmission medium and the termination mechanism. The inherent resistive properties of the conductive materials provide the necessary energy dissipation without requiring separate absorption materials or antenna structures.
4Reliability
If additional absorber layers are added to the circuit board to achieve wave termination, then signal reflection is minimized, but manufacturing complexity and cost increase
Solution Approach 1:
The wave termination function is combined with the existing multi-layer substrate structure by creating through-holes that connect conductive layers across the substrate. This utilizes the existing layer structure for its intended purpose while simultaneously providing termination, eliminating the need for additional absorber layers.
Solution Approach 2:
The termination effect is achieved by changing the electrical parameters (resistance and capacitance) through the through-hole configuration and conductive layer connections rather than by adding materials with different physical properties. This allows termination to be achieved through geometric and material parameter optimization of existing structures.
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 design results in a low-reflection, cost-effective wave termination that effectively absorbs high-frequency signals, reducing manufacturing costs and eliminating the need for additional absorber layers, while maintaining high signal integrity and minimizing interference.
Implementation Method 1
a second substrate layer made of a second material with a second loss factor in order to attenuate, dampen, or absorb the signal
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a radar system (2) for a vehicle for detecting the surroundings thereof, with a printed circuit board (4), comprising a wave termination (36) with a termination line (78), a signal line (38) connected thereto for transmitting a high-frequency signal, a first substrate layer (22), produced from a first material with a first loss factor, a first layer (20) applied to the first substrate layer (22), said first layer comprising the signal line (38), a second substrate layer (26), produced from a second material having a second loss factor which is larger than the first loss factor, and a second layer (28) applied to the second substrate layer (26), said second layer comprising the termination line (78). The invention further relates to a printed circuit board (4) for such a radar system (2).