Radar Level Gauge H01-Mode Transducer Parasitic Mode Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Radar level gauges using H01-mode electromagnetic waves in circular waveguides face interference from parasitic modes due to the discrete layout of radiating elements, which negatively impact performance.
Innovation Solution
The use of N-1 concentric feeder rings, where N is three or greater, with radiating elements placed at radial zeroes of the H0N-mode's electrical field to minimize unwanted modes, and adjusting the amplitude of each ring to cancel 'intermediate' modes, significantly suppressing parasitic modes such as H02, H03, and H04.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If discrete radiating elements are used in concentric rings to generate H01-mode waves, then the desired H01-mode is produced, but parasitic modes (H02, H03, H04) are also generated causing interference
Solution Approach 1:
The patent applies local quality by positioning radiating elements at specific radial locations corresponding to the zeroes of the H0N-mode electrical field. This selective placement ensures that parasitic modes are not excited at these specific locations, while the desired H01-mode is maintained. Each radiating element's position is optimized locally to suppress unwanted modes without compromising the primary measurement function.
Solution Approach 2:
The patent changes the spatial parameter (radial position) of the radiating elements to coincide with the zeroes of the H0N-mode electrical field. By adjusting this critical parameter, the excitation of parasitic modes is minimized. The amplitude parameters of different rings are also adjusted to further suppress intermediate modes, demonstrating parameter optimization to resolve the contradiction between generating desired modes and suppressing parasitic modes.
2Object-affected harmful factors
If amplitude of each ring is adjusted to cancel intermediate modes, then parasitic modes are suppressed, but device complexity increases
Solution Approach 1:
The patent optimizes the amplitude parameters of each feeding ring to achieve cancellation of intermediate parasitic modes. By carefully adjusting these amplitude parameters, the system suppresses unwanted modes while maintaining the desired H01-mode. This parameter optimization approach provides a systematic method to reduce parasitic mode interference without requiring overly complex structural modifications.
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 approach enhances the strength of the desired H01-mode while substantially suppressing parasitic modes, reducing disturbances and improving the accuracy of liquid level measurements in tanks.
Implementation Method 1
an electromagnetic wave transducer arranged to emit the measurement signal into the wave guiding structure as electromagnetic waves
Implementation Method 2
a receiver for receiving the microwave signal reflected against the surface of the liquid
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
A radar level gauge having a wave guiding structure arranged to guide a measurement signal towards the surface and to return the reflected signal, and an electromagnetic wave transducer arranged to emit the measurement signal into the wave guiding structure as electromagnetic waves. The electromagnetic wave transducer has a plurality of radiating elements arranged in N-1 concentric feeder rings, where a radius of each feeder ring coincides with a radial zero of an electrical field of the H0N-mode, and feeding circuitry connected to feed the measurement signals from the transceiver circuitry to the radiating elements, thereby causing the electromagnetic wave transducer to excite electromagnetic waves in the H01-mode. With this choice of feeder ring radii, the H0N mode will not be excited.