Compound Loop Antenna Coupling for Subterranean RF Transfer
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Solution Overview
Problem
Radio transceivers located below ground, such as in water utility metering pits, face poor radio frequency (RF) propagation due to absorption, refraction, and reflection of electromagnetic waves, leading to increased costs and reduced battery life, as conventional antenna designs are inefficient and size-constrained, and physical contacts cannot be used due to hermetic sealing requirements.
Innovation Solution
The use of compound loop (CPL) antennas that are capacitively and inductively coupled, allowing for efficient RF energy transfer between antennas without physical connections, enabling hermetic sealing and improved radiation efficiency, with the antennas being configured to operate orthogonally and with comparable E and H field magnitudes for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional antenna designs are used below ground, then the transceiver can be physically located in the water pit, but RF propagation is poor due to absorption, refraction, and reflection
Solution Approach 1:
The patent introduces an intermediate coupling structure consisting of a first antenna below ground and a second antenna above ground that are capacitively coupled. This intermediary system transfers RF energy from the subterranean environment to the above-ground environment, bypassing the harmful effects of the water pit structure on direct RF propagation.
Solution Approach 2:
The patent replaces direct physical contact connections (mechanical system) with electromagnetic field-based capacitive coupling. This substitution allows RF energy transfer without physical penetration of the hermetic seal, eliminating the need for cable feedthroughs while maintaining electrical connection functionality.
2Reliability
If the transceiver is hermetically sealed for twenty year operating life, then water vapor barrier is maintained, but no physical contacts can be used to transfer RF energy
Solution Approach 1:
The capacitive coupling structure acts as an intermediary that transfers RF energy across the hermetic boundary without requiring physical penetration. The electric field couples between the first antenna (inside the sealed enclosure) and the second antenna (outside), enabling energy transfer while maintaining the integrity of the hermetic seal.
Solution Approach 2:
The patent replaces mechanical cable feedthroughs with electromagnetic field-based capacitive coupling. This substitution eliminates the need for physical contacts that would compromise the hermetic seal, using instead a non-contact electric field coupling mechanism to transfer RF energy across the sealed boundary.
3Reliability
If more base stations are installed to supply adequate network coverage, then RF propagation coverage is improved, but transmit power levels need to be increased which reduces battery life
Solution Approach 1:
The capacitive coupling system with above-ground re-radiating antenna acts as an intermediary that amplifies and redirects RF energy. By placing the second antenna above ground where propagation conditions are superior, the system achieves better coverage without requiring increased transmit power from the battery-powered subterranean transceiver.
Solution Approach 2:
The patent moves the radiating element from the three-dimensional constrained subterranean environment to the open above-ground space. This dimensional transition exploits the superior RF propagation characteristics of above-ground environments, achieving extended coverage without increasing power consumption in the battery-limited subterranean device.
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 achieves efficient RF energy transfer with minimal loss, allowing for reliable communication and extended battery life while maintaining hermetic sealing, effectively addressing the challenges of poor RF propagation and size constraints in non-ideal environments.
Implementation Method 1
compound loop (CPL) antennas that are capacitively and inductively coupled, allowing for efficient RF energy transfer between antennas
Implementation Method 2
compound loop (CPL) antennas that are capacitively and inductively coupled, allowing for efficient RF energy transfer between antennas
Implementation Method 3
the antennas being configured to operate orthogonally and with comparable E and H field magnitudes for enhanced performance
Data Source
AI summary
Source radio frequency energy (RF) is coupled wirelessly, with no direct physical contact, between two compound loop (CPL) antennas across a variety of barriers such as plastic, human tissues, glass, and air. The compound coupling interface is highly efficient in transferring the RF energy from a source including one CPL antenna to a destination including a second CPL antenna. A re-radiating structure including a further CPL antenna or a different type of antenna may be connected on the destination side to completely physically isolate the source side from the destination side. When the destination coupling antenna is removed, the source coupling antenna may operate as an efficient radiator at the desired operating frequencies. Likewise, the destination coupling antenna may operate as an efficient radiator in the absence of the source coupling antenna.