Quadrature Coupler Field Applicator for RF Reflection Handling
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Solution Overview
Problem
Solid-state cooking apparatuses face inefficiencies and potential damage due to poor input return losses and impedance mismatches caused by varying food loads and reflective materials, which conventional systems attempt to mitigate with ferrite circulators but at the cost of additional losses and reliability issues.
Innovation Solution
A solid-state cooking apparatus with a field applicator that uses a quadrature coupler to split RF signals into linearly polarized waves, forming circularly or elliptically polarized waves, and includes a switching unit controlled by a controller to manage power reflections through RF shorts, opens, or dummy loads, improving impedance matching and power handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferrite circulators or isolators are used to redirect reflected power, then PA damage is prevented, but additional losses and costs increase
Solution Approach 1:
The patent extracts the harmful reflected power from the main signal path using a directional coupler, separating it into a dedicated isolation port where it can be safely dissipated without affecting the main cooking cavity operation. This removes the need for ferrite circulators while maintaining PA protection.
Solution Approach 2:
The patent introduces an intermediary component - a directional coupler with an isolation port - that mediates between the PA and the cooking cavity. This intermediary captures reflected power before it can damage the PA, while introducing minimal losses compared to ferrite circulators.
2Reliability
If ferrite circulators or isolators are used to redirect reflected power, then PA damage is prevented, but device costs increase
Solution Approach 1:
The patent extracts the PA protection function from expensive ferrite circulators and implements it using a directional coupler with an isolation port, significantly reducing component costs while maintaining the same protective function.
Solution Approach 2:
The patent replaces expensive ferrite circulators with a more economical directional coupler configuration that achieves the same PA protection function at lower cost, making the system more economically viable.
3Productivity
If the PA is tuned for frequency-independent load, then best performance is achieved with nominal impedance, but impedance mismatch occurs with varying food loads
Solution Approach 1:
The directional coupler acts as an intermediary that monitors the actual load conditions in the cooking cavity and provides feedback information about reflected power, enabling the system to adapt to varying food loads while maintaining optimal PA performance.
Solution Approach 2:
The patent implements a feedback mechanism where the directional coupler monitors reflected power from the cooking cavity, allowing the system to detect impedance mismatches caused by varying food loads and adjust operation accordingly to maintain PA performance.
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 solution enhances the efficiency and reliability of the cooking process by dynamically managing power reflections, reducing the risk of damage to components and improving cooking performance across varying loads, while minimizing additional losses and costs.
Implementation Method 1
a first antenna element for emitting a first wave based on the first signal into the cooking cavity, and a second antenna element for emitting a second wave based on the second signal into the cooking cavity. The first and second waves are preferably each linearly polarized electromagnetic waves
Implementation Method 2
The first and second linearly polarized electromagnetic waves preferably form, together and in the cooking cavity, a circularly or elliptically polarized electromagnetic wave
Implementation Method 3
in the second mode, the predefined load equals a dummy load configured to dissipate the signal received at the isolated port of the quadrature coupler
Data Source
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AI summary
The present invention relates to a solid-state cooking apparatus. The present invention further relates to a field applicator for applying an electromagnetic wave, preferably to a cooking cavity of a solid-state cooking apparatus. The field applicator comprises a quadrature coupler for splitting a radiofrequency signal over a pair of antenna elements. The isolated port of the quadrature coupler is connected to a predefined load. The solid-state cooking apparatus is operable in at least one of a first mode and second mode, wherein, in the first mode, the predefined load equals an RF short or an RF open, and, in the second mode, the predefined load equals a dummy load configured to dissipate the signal received at the isolated port of the quadrature coupler.