Broadband RF Magnetic Antenna Using PLL and Segmented Resonators
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Solution Overview
Problem
Current RF magnetic sensors are limited by bandwidth, size, power consumption, temperature sensitivity, and detection sensitivity, particularly for high-frequency and low-frequency applications, and require cryogenic cooling or large, high-power devices for effective operation.
Innovation Solution
A broadband integrated RF magnetic antenna using quartz MEMS resonators with a phase lock loop (PLL) system, where two resonators are bonded on a semiconductor substrate, one coated with a magnetostrictive film and the other not, to enhance frequency shift detection and reduce temperature sensitivity, allowing for high-bandwidth operation and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetostrictively-driven piezoelectric resonators are used for sensing magnetic RF fields, then sensitivity is enhanced by high mechanical gain (Q), but bandwidth is limited to roughly the linewidth of the mechanical resonance
Solution Approach 1:
The system is divided into two separate resonators: one optimized for high-Q sensitivity measurements and another for broader bandwidth operation. This segmentation allows each resonator to be independently optimized for its specific function, resolving the contradiction between sensitivity and bandwidth
Solution Approach 2:
A phase lock loop (PLL) circuit serves as an intermediary that bridges the high-Q resonator and the measurement system. The PLL extracts frequency modulation signals from the high-Q resonator, enabling bandwidth extension beyond the mechanical resonance linewidth while preserving the sensitivity advantages of high-Q operation
2Loss of energy
If dipole or monopole antennas are used for detecting RF signals, then radiation efficiency is maintained, but antenna length must be roughly one-half to one-quarter of the RF wavelength, limiting size reduction
Solution Approach 1:
The patent replaces traditional electromagnetic dipole/monopole antenna structures with a magnetostrictively-driven piezoelectric resonator system. This substitution transitions from mechanical vibration-based detection to magnetic field coupling, enabling extreme sub-wavelength dimensions while maintaining effective RF signal detection through the magnetostrictive effect
Solution Approach 2:
The system employs composite material structures combining piezoelectric materials with magnetostrictive materials. This composite approach enables the resonator to couple both mechanical vibration and magnetic field effects, achieving efficient RF signal detection in a compact form factor that would be impossible with single-material traditional antennas
3Measurement precision
If cryogenically cooled SQUID detectors are used for direct magnetic detection, then detection sensitivity reaches femto tesla levels, but device size is large and power consumption is high (≥195 mW)
Solution Approach 1:
The patent changes the operating temperature parameter from cryogenic (4.2 K for SQUIDs) to room temperature. This parameter change is achieved by transitioning from superconducting quantum-based detection to magnetostrictively-driven piezoelectric resonators, which maintain high sensitivity without requiring cryogenic cooling, thereby dramatically reducing power consumption
Solution Approach 2:
The invention replaces expensive, complex, and power-hungry SQUID detectors with simpler, room-temperature operable magnetostrictive resonators. These resonators achieve comparable sensitivity without the need for cryogenic infrastructure, making the system more practical for portable and integrated applications
4Adaptability or versatility
If conventional RF magnetic sensors are used for high-frequency communication signals, then detection capability is limited, but bandwidth requirements for high-content communication signals are not met
Solution Approach 1:
The system employs dynamic frequency tuning capabilities through the phase lock loop, which can track and lock onto varying RF frequencies. This dynamic operation enables the sensor to adapt to different communication frequency bands and modulations, providing both wide bandwidth for high-content signals and maintained detection precision across the operating range
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 solution achieves high sensitivity and low temperature sensitivity, enabling detection of femto-to-pico tesla magnetic fields with reduced size and power consumption, and extends bandwidth beyond limitations of previous resonant-based sensors, making it suitable for high-content communication signals.
Implementation Method 1
one coated with a magnetostrictive film
Implementation Method 2
quartz MEMS resonators
Data Source
AI summary
A RF antenna or sensor comprising substrate with at least a pair of resonators bonded thereto, whereon a first one of the at least a pair of resonators is coated with a magnetostrictive film and a second one of the at least a pair of resonators is not coated with a magnetostrictive film. The resonators are preferably connected to sustaining circuits to form oscillators and the oscillators a preferably used within a phase lock loop to detect the magnetic component of an incident RF field with a bandwidth determined by the phase lock loop. Also disclosed is a method of making a RF sensor or antenna comprises providing a substrate of a semiconductor material, simultaneously forming two resonators on the substrate, and during the forming of the resonators a resist coating partially covering a first one of the resonators and completely covering a second one of the resonators is applied. Then, a magnetostrictive material is deposited to regions not covered by the resist coating. Thereafter, the resist coating is removed thereby leaving the magnetostrictive material deposited on only one of the two resonators.