Calculation of radiated electromagnetic power from bulk acoustic wave resonators

Abstract

In this paper, a general technique for calculating the radiated electromagnetic fields from an electrically small bulk acoustic wave resonator in the vicinity of acoustic resonance is presented. The BAW resonator is analyzed as an electrically small microstrip antenna on a piezoelectric substrate. By the application of the surface equivalence principle, the device is replaced by equivalent sources. The radiated far fields found from the equivalent sources are integrated over the upper half plane to determine the total amount of radiated EM power as a function of frequency. The result is general enough to characterize the electromagnetic radiation from arbitrarily shaped metalizations, and the antenna pattern and polarization of the radiation may also be determined. The theoretical results are experimentally confirmed by measuring the radiated EM power spectrum from lithium niobate and quartz resonators.

Piezoelectromagnetic waves in a ceramic plate

“…The inclusion of electromagnetic waves as a special case is a fundamental difference between the piezoelectromagnetic theory and the quasistatic theory. This qualitative difference is essential when electromagnetic waves are involved, e.g., radiation [3]- [6]. • When the speed of light goes to infinity.…”

“…Therefore, it does not describe the wave behavior of electromagnetic fields. Electromagnetic waves generated by mechanical fields [2] need to be studied in the calculation of radiated electromagnetic power from a vibrating piezoelectric device [3]- [6], and they are relevant in acoustic delay lines [7] and wireless acoustic wave sensors [8] in which acoustic waves produce electromagnetic waves or vise versa. When electromagnetic waves are involved, the complete set of Maxwell's equations need to be used, coupled to the mechanical equations of motion.…”

Acoustic Gap Waves in Piezoelectromagnetic Materials

“…For example, for Bleustein-Gulyaev waves the difference is of the order of 10 57 and 10 516 for an electroded and unelectroded ceramic half space, respectively [20]. However, the fully dynamic nature of piezoelectromagnetic waves can describe electromagnetic radiation [3][4][5][6] but quasistatic piezoelectric waves cannot. Equation ( 25) reduces to the dispersion relation for the anti-symmetric quasistatic piezoelectric gap wave in [21] when the speed of light goes to infinity.…”

“…Therefore it does not describe the wave behavior of electromagnetic fields. Electromagnetic waves generated by mechanical fields [2] need to be studied in the calculation of radiated electromagnetic power from a vibrating piezoelectric device [3][4][5][6], and are also relevant in acoustic delay lines [7] and wireless acoustic wave sensors [8] where acoustic waves produce electromagnetic waves or vise versa. When electromagnetic waves are involved, the complete set of Maxwell's equations need to be used, coupled to the mechanical equations of motion.…”

Design and fabrication of a MEMS passive pressure sensor

“…In the case of a resonant structure, the change of resonant frequency is a good measure of capacitance change. An interesting novel method, which incorporates a Bulk Acoustic Wave (BAW) Resonator, senses the change of total radiated power as a function of capacitance [7] . The impedance sensing structure in the reference article utilizes a lossy R-C network, which lowers the Quality Factor, making wireless detection more difficult.…”