Quartz MEMS Resonator Antenna With Magnetostrictive RF Coupling
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Solution Overview
Problem
Traditional wire-based RF antennas have low efficiency for wavelengths larger than their physical size due to high reactance and low radiation resistance, limiting their effectiveness in handheld communication systems, particularly for VLF to UHF frequencies, and existing piezoelectric resonators with low Q values and high temperature sensitivity are inadequate for compact commercial and military applications.
Innovation Solution
The development of quartz MEMS piezoelectric resonators with high Q values (≥10,000) and improved frequency stability, integrated with magnetostrictive films, allowing for the conversion of electromagnetic waves to acoustic signals and enabling the creation of compact, high-efficiency RF antennas that can be fabricated at the chip scale and connected in arrays for enhanced signal strength and frequency hopping capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional wire-based antennas are used for wavelengths larger than their physical size, then the antenna structure is simple, but the efficiency is low due to high reactance and low radiation resistance
Solution Approach 1:
The patent replaces traditional electromagnetic wire-based antennas with a piezoelectric resonator system that converts electromagnetic signals to mechanical vibrations and back. The piezoelectric element transforms the RF electrical signal into mechanical vibrations at its resonant frequency, which are then converted back to electrical signals by the magnetostrictive material, enabling efficient energy transfer without requiring large physical dimensions proportional to wavelength
Solution Approach 2:
The patent changes the operating parameter from direct electromagnetic radiation to mechanical resonance. By operating the piezoelectric resonator at its mechanical resonant frequency, the system achieves high Q-factor (quality factor) energy storage and transfer, dramatically improving efficiency compared to traditional antennas operating below their resonant frequency
2Reliability
If PZT or AlN piezoelectric elements are used, then the antenna can be made compact, but the Q value is low (≤1000) and frequency drift over temperature is high (≥3000 ppm)
Solution Approach 1:
The patent uses a composite structure combining piezoelectric material (for electromechanical conversion) with magnetostrictive material (for mechanical-to-electrical conversion). This composite approach enables the resonator to function as both transmitter and receiver while achieving high Q values and temperature stability through the synergistic properties of the combined materials
3Loss of energy
If high Q piezoelectric resonators are used for RF antenna, then the efficiency is improved, but the device complexity increases due to integration requirements
Solution Approach 1:
The patent merges the transmitter and receiver functions into a single piezoelectric resonator device. The same piezoelectric element with magnetostrictive coating that converts electrical to mechanical energy for transmission also converts mechanical vibrations back to electrical signals for reception, eliminating the need for separate transmit and receive antenna structures
Solution Approach 2:
The piezoelectric resonator serves multiple functions: it acts as both the transmitting antenna and receiving antenna, provides frequency selection through its resonant properties, and enables signal amplification through its high Q-factor. This multi-functionality reduces overall system complexity despite the sophisticated material composition
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 quartz MEMS piezoelectric resonators achieve magnetic field sensitivities of <10−14 T/√Hz with improved temperature stability and order-of-magnitude better performance compared to existing technologies, enabling efficient RF energy transmission and reception without additional antenna elements, and provide directional and polarization information through unique frequency signatures.
Implementation Method 1
a piezoelectric element, thus converting the magnetic field energy to strain energy and then strain into a voltage in the piezoelectric element. At the piezoelectric element's mechanical resonance, this voltage is increased by the mechanical Q of the resonance.
Implementation Method 2
thru a combination of a magnetostrictive material added to a piezoelectric element, thus converting the magnetic field energy to strain energy
Data Source
AI summary
A RF antenna having a magnetostrictive film may be made by patterning selected portions of a top surface of the quartz wafer for deposition of electrode metal and deposition of the magnetostrictive film and depositing the electrode metal and the magnetostrictive film; temporarily bonding the quartz wafer to a handle wafer; thinning the quartz wafer to a desired thickness; etching the quartz wafer to define the outlines of at least one quartz resonator bearing the electrode metal and the magnetostrictive film; patterning selected portions of a bottom surface the at least one quartz resonator for deposition of electrode metal and at least one bond pad and depositing the electrode metal and the at least one bond pad; bonding the at least one quartz resonator to a substrate wafer; and releasing the at least one quartz resonator from the handle wafer.