About

Stephen Campbell, M.S, is an Extension Educator specializing in Agronomy, with a focus on forages, soil health, cover crops, turfgrass, golf and sports turf. He works out of the Penn State Extension's Butler County office and covers the counties of Butler, Beaver, Armstrong, and Indiana. Stephen attended Penn State University, where he earned his Bachelor of Science degree in Turfgrass Science, with minors in Animal Sciences and Sociology. He further pursued his Master of Science in Turfgrass Science/Horticulture at Purdue University, with an emphasis on Agricultural Sciences Education and Communication, under the guidance of Dr. Cale Bigelow and Dr. B Allen Talbert. His master's project was titled "Evaluating and Assessing Needs of Turfgrass for Indiana High Schools." Stephen's expertise includes agronomy, forages, soil health, cover crops, and turfgrass management. He looks forward to working with stakeholders around the state to advance knowledge and practices in these areas.

Research topics

• Optics
• Physics

Selected publications

• Supplementary document for Realization of Arbitrary Biaxial Metamaterials Enabled by an Interleaved Metallic Patch-Rod Structure - 7819069.pdf

  Figshare · 2026-03-13

  articleOpen access

  Equivalent Circuit Model, Field enhancement, and angular sensitivity

  PublisherDOI

• Supplementary document for Realization of Arbitrary Biaxial Metamaterials Enabled by an Interleaved Metallic Patch-Rod Structure - 7819069.pdf

  Figshare · 2026-03-13

  articleOpen access

  Equivalent Circuit Model, Field enhancement, and angular sensitivity

  PublisherDOI

• Deep Learning for Real Time Antenna Array Failure Recovery

  IEEE Transactions on Antennas and Propagation · 2026-01-01

  article

  We present an exceptional AI-assisted framework for fast and robust recovery of phase failures in planar antenna arrays. Using a U-Net-based neural architecture trained to replicate the results of gradient descent optimization. Effectively, removing the reliance on time consuming optimization methods for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> recovery. Our approach is able to be adapted to any array geometry and provides failure recovery for up to 50% failure rate. Our method recovers on average over 90% of the performance achieved by an equivalent optimization—often matching or exceeding key directivity metrics. The model’s adaptability allows the user to dictate in the training process what array characteristics need recovered, such as null placement and sidelobe suppression, making it highly effective even in high-failure scenarios. Leveraging GPU-accelerated neural network predictions we reduce computation times dramatically, achieving a remarkable 67,127x <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> speedup over conventional optimization methods.

  PublisherDOI

• Supplementary document for Realization of Arbitrary Biaxial Metamaterials Enabled by an Interleaved Metallic Patch-Rod Structure - 7819069.pdf

  Figshare · 2026-03-13

  articleOpen access

  Equivalent Circuit Model, Field enhancement, and angular sensitivity

  PublisherDOI

• Realization of arbitrary biaxial metamaterials enabled by an interleaved metallic patch–rod structure

  Figshare · 2026-03-13

  otherOpen access

  This Letter describes a method for synthesizing arbitrary biaxial metamaterials based on an interleaved metallic patch–rod structure. By tailoring the patch lengths and rod spacing, the effective permittivity tensor (ε_x, ε_y, ε_z) can be independently engineered while maintaining μ≈1. The suggested structure exhibits nearly dispersionless, low-loss electromagnetic behavior by operating in the deeply subwavelength regime. The homogenization model is validated through full-wave simulations, which show excellent agreement between the synthesized and equivalent bulk media. Although our approach has been demonstrated in the microwave region, it is scalable to terahertz and optical frequencies and hence represents a general framework for designing anisotropic media with customizable biaxial response.

  PublisherDOI

• Circuit-Loaded Microwave Metadevices: Current State of the Art and Future Directions

  IEEE Microwave Magazine · 2026-02-27

  article

  A substantial body of research explores the microwave applications of metamaterial- and metasurface-enabled devices (i.e., metadevices). While traditional designs often achieve disruptive performances, integrating these devices with circuit components can enable multifunctional and actively tunable behaviors. This article offers a comprehensive, categorical review of circuit-loaded metadevices that achieve frequency-selective transmission, reflection, filtering, tunability and reconfigurability, surface wave suppression, harmonic generation, nonreciprocal scattering, and more. This topic will particularly interest the microwave community, as the linear and nonlinear devices discussed operate chiefly within the microwave frequency band. Therefore, this article focuses on applications that primarily utilize microwave and RF frequency bands.

  PublisherDOI

• Realization of arbitrary biaxial metamaterials enabled by an interleaved metallic patch–rod structure

  Figshare · 2026-03-13

  otherOpen access

  This Letter describes a method for synthesizing arbitrary biaxial metamaterials based on an interleaved metallic patch–rod structure. By tailoring the patch lengths and rod spacing, the effective permittivity tensor (ε_x, ε_y, ε_z) can be independently engineered while maintaining μ≈1. The suggested structure exhibits nearly dispersionless, low-loss electromagnetic behavior by operating in the deeply subwavelength regime. The homogenization model is validated through full-wave simulations, which show excellent agreement between the synthesized and equivalent bulk media. Although our approach has been demonstrated in the microwave region, it is scalable to terahertz and optical frequencies and hence represents a general framework for designing anisotropic media with customizable biaxial response.

  PublisherDOI

• Analytical framework for angular dispersion engineering of metasurface optics

  Optics Express · 2025-12-12

  articleOpen access

  This work presents a method for modeling and designing phase gradient metasurface profiles to account for varied response dependent on field incidence angle or angular dispersion, a phenomenon of significant recent interest. This method not only can improve existing metasurface design through informed selection of meta-atoms, but enables designs through more generalized metasurface placement, rather than the traditional limitation to being the first or functionally sole element of a given optical system. This work demonstrates the benefits of the method through sample designs demonstrating size, weight, and power (SWaP) reduction, field curvature control, and aberration correction.

  PublisherDOI

• Multiphysics Inverse‐Design of Multifunctional Freeform Meta‐Radomes

  Small Structures · 2025-10-08 · 1 citations

  articleOpen access

  Modern multifunctional antenna systems are critical for next‐gen wireless communications, including 5G/6G and beyond. Whether deployed in dense urban environments or in remote areas, these systems must be protected from environmental hazards and electromagnetic interference while also being inconspicuous to the lay person. Radomes, which protect antennas have been investigated as a solution to address the multitude of potential operational threats. Successfully mitigating this protective covering's impact on antenna performance has long been thought to be a suitable implementation of a radome device. However, to meet the escalating demands for systems that surpass current state‐of‐the‐art performance, the radome structure itself is now emerging as a critical focal point for multifunctional enhancement. To meet this need, a multiphysics inverse‐design strategy is introduced for realizing bespoke multifunctional meta‐radomes. Here it is demonstrated that by exploiting physics‐informed adjoint optimization to generate subwavelength meta‐structures one can simultaneously target user‐defined mechanical and electromagnetic performances in a freeform additively manufacturable structure. The optimized design provides 9.9 dB gain enhancement of the base antenna system while being able to survive over 4400 N (≈1000 lbs) of force. Subsequent testing of the fabricated structure shows excellent agreement with simulation.

  PublisherOA PDFDOI

• Multi-Band Wide Field-of-View Directivity Enhancing Dielectric Rod Medium

  2025-07-13

  article1st authorCorresponding

  Dielectric rods can realize large scattering cross sections when interacting with electromagnetic waves. By optimizing multiple layers around the rod its scattering cross section can be tailored to realize enhanced and multi-band performance. Moreover, aperiodic arrangements of multi-layer dielectric rods can be optimized to enhance the gain of existing antenna systems similar to lenses, albeit with significantly reduced size and weight. A multiobjective optimized mutli-layer aperiodic multi-band rod enhancement medium is presented.

  PublisherDOI

Frequent coauthors

• Douglas H. Werner

  Pennsylvania State University

  163 shared

• Pingjuan L. Werner

  Pennsylvania State University

  64 shared

• Eric B. Whiting

  50 shared

• Lei Kang

  Pennsylvania State University

  33 shared

• R. Jenkins

  Pennsylvania State University

  31 shared

• Jogender Nagar

  Pennsylvania State University

  29 shared

• Galestan Mackertich-Sengerdy

  Pennsylvania State University

  18 shared

• Donovan E. Brocker

  Milwaukee School of Engineering

  16 shared