Convetionally, the operating frequency of an antenna strictly dictated by its electrical size. Our work circumvent the limitation  by introducing electron spin precession effect at ferromagnetic resonance (FMR) frequency to design electrically small antennas.

• Resonance Frequency Indepent from Electrical Size: The FMR frequency is dominated by the bias magnetic field. Therefore, the FMR allows antenna to resonate at a extremely small electrical size.

• Reducing Radiation Q Factor: High material permeability effectively push the stored energy out of the ferrite, lowering the radiation quality factor and liberating low-profile elements from efficiency-killing ground plane interactions.

• Wide Magnetic Tunability: Because the operating frequency depends on the FMR rather than the physical structure, the antenna can be dynamically tuned across a broad frequency spectrum simply by altering an external DC bias field.

S. -M. Huang, J. Yu, A. Geiler, F. Hussain and Y. E. Wang, "An Electrically Small Antenna Leveraging on Circularly Polarized Radiation of Electron Spin Precessions," in IEEE Transactions on Antennas and Propagation, June 2026.

We developed a systematic design methodology for millimeter-wave (mmWave) magnetic bandpass filters utilizing M-type barium hexaferrite (BaM). This research bridges traditional microwave filter theory with the distinct physics of magnetic materials. The contribution of this work includes:

• Equivalent Circuit Modeling: The study introduces a novel equivalent circuit model that accurately quantifies the coupling efficiency between electromagnetic (EM) waves and ferrimagnetic resonance (FMR).

• Planar PCB Integration: Instead of complex thin-film deposition on costly substrates like sapphire, this method integrates standalone bulk BaM spheres directly into non-through drilled vias on standard Rogers 4003C printed circuit boards (PCBs). This offers high substrate flexibility and eliminates complex microfabrication processes. 

• Static Biasing Architecture: The design utilizes a compact, permanent NdFeB static magnet to align the material's internal anisotropy field. This successfully eliminates the need for bulky, power-consuming external electromagnets and highly practical for real-world applications.

Q. Gao, L. K. Yeung, Y. Liu, A. Geiler and Y. E. Wang, "Systematic Design of Planar Millimeter-Wave Filters Based on Hexagonal Barium Ferrite (BaM)," in IEEE Transactions on Microwave Theory and Techniques, vol. 73, no. 5, pp. 2499-2511, May 2025.

• A novel stacked magnetic pendulum array (MPA) is proposed as an antenna for efficient transmission at a resonance frequency of 715 Hz. The MPA structure consists of an array of magnets rows and a solenoid that encompasses the array.

• The radiation fo the MPA is created by rapidly rotating the magnets array.  A comprehensive analysis to study the performance of the MPA, including field strength, resonance frequency, and transmission efficiency are presented in this work. 

• To demonstrate broadband transmission with the MPA, a binary frequency shift keying (BFSK) signal is transmitted through MPA at a data rate of 18 bps.

F. Fereidoony, S. P. M. Nagaraja, J. P. D. Santos and Y. E. Wang, "Efficient ULF Transmission Utilizing Stacked Magnetic Pendulum Array," in IEEE Transactions on Antennas and Propagation, vol. 70, no. 1, pp. 585-597, Jan. 2022.

This work introduces a powerful and versatile 3-D Finite-Difference Time-Domain (FDTD) multiphysics modeling method designed for simulating arbitrarily shaped RF magnetic devices. By jointly solving Maxwell’s equations (electrodynamics) and the Landau-Lifshitz-Gilbert (LLG) equation (micromagnetics), the framework delivers a physically intuitive solution for devices where full full-wave electrodynamic effects cannot be ignored.

L. Li and Y. E. Wang, "Versatile Modeling With FDTD of Maxwell’s and LLG Equations," in IEEE Transactions on Antennas and Propagation, vol. 74, no. 6, pp. 5609-5622, June 2026.

Frequency-selective limiters (FSLs) are critical components for protecting sensitive RF receivers from high-power Interference. 

However, simulation of ferrite-based coplanar waveguide (CPW) FSLs suffers from extreme magnetic field nonuniformity across their width and thickness, meaning electron spins at the corners behave entirely differently than those in the center. Until now, researchers had to choose between ultra-slow full-wave electromagnetic simulators or oversimplified models that ignored this spatial reality.

This work presents a novel, physics-based nonlinear circuit model implemented in Advanced Design System (ADS) that bridges the gap between raw physics and fast circuit simulation. The proposed circuit model was validated by the actual measurement of a CPW FSL.

Q. Gao, M. E. Fordham, H. Cui and Y. E. Wang, "A Compact Circuit Model for Frequency-Selective Limiters With Strong Field Nonuniformity," in IEEE Transactions on Microwave Theory and Techniques, vol. 71, no. 12, pp. 5124-5134, Dec. 2023.