MMIC-to-Waveguide PCB Coupling to Reduce RF Transition Loss
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Solution Overview
Problem
Existing automotive radar systems experience significant energy losses due to multiple transitions of RF energy from the MMIC to the waveguide, leading to reduced radar efficiency and sensitivity.
Innovation Solution
A direct energy path is established from the MMIC to the waveguide through a coaxial structure on a multi-layer PCB, transforming RF energy from a transverse magnetic (TM) mode to a transverse electric (TE) mode using a ridge waveguide, minimizing transitions and energy losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple transitions of RF energy from MMIC to waveguide are used, then the radar system can be manufactured with standard PCB antenna structures, but energy losses increase significantly
Solution Approach 1:
The patent extracts and eliminates the intermediate transition structures (microstrip probes, adhesive layers, and waveguide transitions) that cause energy losses. By directly coupling the MMIC to the waveguide through a simplified PCB structure with the MMIC mounted on the front side and waveguide on the back side, the harmful transition interfaces are removed, thereby reducing energy losses while maintaining manufacturability.
2Loss of energy
If a direct energy path is established from MMIC to waveguide, then energy losses are reduced, but the device structure becomes more complex
Solution Approach 1:
The patent merges the MMIC mounting structure with the waveguide structure by placing them on opposite sides of the same PCB. The front side of the PCB serves as the mounting substrate for the MMIC, while the back side contains the waveguide, creating a direct energy path through the PCB thickness. This integration reduces the number of separate components and assembly steps, thereby managing structural complexity while achieving direct energy coupling.
3Ease of manufacture
If standard PCB antenna structures with multiple transitions are used, then manufacturing is easier, but radar efficiency and sensitivity are reduced
Solution Approach 1:
The patent removes the intermediate microstrip probe and adhesive layer structures that are present in standard PCB antenna designs. By establishing a direct coupling path between the MMIC and waveguide through the PCB substrate without these intermediate layers, the design eliminates the sources of energy loss and signal degradation, thereby improving radar efficiency and sensitivity while remaining manufacturable.
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 configuration significantly reduces energy losses, enhancing radar efficiency and sensitivity by maintaining a substantially linear unobstructed pathway for RF energy transmission.
Implementation Method 1
transforming RF energy from a transverse magnetic (TM) mode to a transverse electric (TE) mode using a ridge waveguide
Implementation Method 2
a first waveguide is formed in the second outer layer, and a second waveguide is mounted to the second outer layer over the first waveguide
Data Source
Figure 1~2
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AI summary
An automotive radar system includes a printed circuit board (PCB) formed from a plurality of layers including a first outer layer, a second outer layer, and a plurality of intermediate layers. A coaxial structure extends from the first outer layer to the second outer layer. A monolithic microwave integrated circuit (MMIC) is mounted to the first outer layer and connected to the coaxial structure. A first waveguide is formed in the second outer layer, and a second waveguide is mounted to the second outer layer over the first waveguide. The coaxial structure forms a direct energy path from the MMIC to the first waveguide.