Antenna Module Circuit Layout for Circular Polarization Stability
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Solution Overview
Problem
In circularly polarized wave patch antennas, reflected radio frequency signals re-input to the isolation port cause a phase mismatch, reducing the circularity of the radiated wave, especially in quasi-millimeter and millimeter wave bands where non-reflective termination with chip resistors is difficult to implement.
Innovation Solution
An antenna module design with a distributing/synthesizing circuit and longer second transmission lines to attenuate re-input radio frequency signals, preventing phase mismatch and maintaining circularity by synthesizing and outputting reflected signals through a longer transmission line without chip resistor termination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-reflective termination resistor is connected to the isolation port, then signal reflection is suppressed, but it becomes difficult to implement in quasi-millimeter wave bands above 20 GHz or millimeter wave bands
Solution Approach 1:
The patent introduces a second transmission line as an intermediary element between the isolation port and the radiating element. This transmission line acts as a mediator that provides signal attenuation through its inherent losses, replacing the need for a termination resistor in high-frequency bands where resistors are difficult to implement.
Solution Approach 2:
The patent changes the electrical parameters of the transmission system by adjusting the length and characteristics of the second transmission line. By controlling the transmission line's electrical length and impedance characteristics, the system achieves the desired signal attenuation effect without requiring a physical resistor component.
2Manufacturing precision
If reflected radio frequency signals are re-input to the patch antenna from the isolation port, then the circularity of the radiated wave is reduced, but the signals continue to circulate in the system
Solution Approach 1:
The patent converts the harmful re-circulating reflected signals into a beneficial attenuation mechanism. By designing the second transmission line with specific electrical characteristics, the reflected signals that would normally cause harm are instead used to demonstrate the attenuation effect, thereby protecting the system from re-input damage while maintaining circular polarization quality.
3Loss of energy
If the second transmission line is made longer, then signal attenuation increases, but the transmission line occupies more space
Solution Approach 1:
The patent resolves the space-length contradiction by transitioning from a one-dimensional linear transmission line to a two-dimensional or three-dimensional folded configuration. The transmission line is folded back on itself multiple times, allowing it to achieve the necessary electrical length for signal attenuation while occupying minimal physical space on the substrate.
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 design effectively suppresses re-input of unnecessary radio frequency signals, maintaining the circularity of the radiated wave even in high-frequency bands by increasing signal attenuation through the longer transmission line, ensuring sufficient non-reflective termination.
Implementation Method 1
the second transmission line is longer than each of the first transmission line, the third transmission line, and the fourth transmission line
Data Source
AI summary
A distributing/synthesizing circuit includes first to fourth ports. A first radio frequency circuit transmits and receives a radio frequency signal to and from the first port through a first transmission line. A second transmission line is connected to the second port. A first radiating element is connected to the third port and the fourth port through a third transmission line and a fourth transmission line, respectively. The distributing/synthesizing circuit distributes and outputs the radio frequency signal input to the first port to the third port and the fourth port, synthesizes radio frequency signals that are reflected by the first radiating element and that are input to the third port and the fourth port to output the synthesized radio frequency signal to the second port. The second transmission line is longer than all of the first transmission line, the third transmission line, and the fourth transmission line.