More Like this

1. Thin Film Enabled Tunable Engineered Substrate for Reconfigurable RF and Microwave Applications

   https://doi.org/10.1109/IWS49314.2020.9360202  

   Ge, Jinqun; Peng, Yujia; West, David; Wang, Guoan (September 2020, 2020 IEEE MTT-S International Wireless Symposium (IWS))

   null (Ed.)

   This paper presents a methodology in the development of miniaturized and electrically tunable RF and Microwave passives with engineered substrate which has high and electrically tunable effective permeability. The perspective substrate is implemented with multiple layers of 100 nm thick Permalloy (Py) thin film patterns embedded on Silicon substrate, and each Py layer consists of an array of 15μm×40μm Py patterns with 5 μm gaps among them to suppress the magnetic loss. The effective permeability of the single layer and ten layers of Py enabled substrate is tunable by the static magnetic field produced from the applied DC current providing a tunability of 3.3% and 18.8%, respectively. Passives are developed on the proposed engineered substrate with a single layer embedded Py to demonstrate the efficacy of the engineered substrate on the design of arbitrary tunable components. Results show that the developed transmission line-based phase shifter provides continuous 90° phase shift from 0.956 GHz to 1.01GHz, and the center frequency of the bandpass filter shifts from 2.42GHz to 2.56GHz continuously. 

   more » « less
2. Characterization of Thin Film Enabled Engineered Substrate for RF Applications

   https://doi.org/10.1109/IEEECONF35879.2020.9330159  

   Ge, Jinqun; Wang, Guoan (July 2020, 2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting)

   null (Ed.)

   Engineered substrate enabled by Permalloy (Ni 80 Fe 20 , Py) thin films has been well developed for RF applications with high and tunable permeability and moderate loss. A full investigation on the characteristics of the engineered substrate is presented in this paper. The loss and equivalent permeability generated by the Py patterns are characterized through a microstrip line model. Multiple factors of Py patterns are taken into consideration to define the performance of the engineered substrate, including filling density, thickness, dimensions, and locations. The analytical results give a detailed guideline for the design of engineered substrate. 

   more » « less
3. Interface induced uniaxial magnetic anisotropy and modified domain patterns in crosslinked silica aerogel/Ni80Fe20 heterostructures

   https://doi.org/10.1007/s00339-025-08449-3  

   Islam, K_Z; Timsina, D.; Sabri, F.; Pollard, S_D (March 2025, Applied Physics A)

   Abstract Silica aerogels have emerged as promising candidates as platforms for a variety of devices, including those used for magnetic logic and sensing. However, their non-planar structure also poses challenges for their use as substrates for thin film devices. For example, substrate disorder is established to strongly influence anisotropy in thin film magnetic materials. Here, we evaluate the substrate effect on induced uniaxial anisotropy in permalloy (Py) thin films and patterned structures, wherein the uniaxial anisotropy is clearly linked to a directionality of the magnetization hysteresis and modifications to zero field domain structures relative to a standard thermally oxidized Si substrate. The strength and direction of this anisotropy vary with location, indicating its non-uniform nature, and is estimated to be as large as 700 J/m³for 25 nm thick permalloy films, and decreases with increasing Py thickness. This substrate induced anisotropy is strong enough to modify the domain structures present in patterned magnetic elements and can have significant implications for the development of magnetic devices on aerogel substrates. Results are compared and found to be consistent with micromagnetic modelling of expected domain structures. 

   more » « less
4. Conformal Wideband Microstrip Patch Antennas on Cylindrical Platforms

   Mitha, Tanzeela; Pour, Maria (November 2018, Progress in electromagnetics research)

   A conformal wideband antenna is investigated and compared with its planar counterpart. First, a planar U-slot patch with about 43% fractional impedance bandwidth is designed. Then, it is mounted on a conformal cylindrical structure. It is observed that the fractional impedance bandwidth of the resulting conformal antenna increases to 50%, when it is bent along the H-plane. It is also found that the cross polarization discrimination of the antenna is improved. The effects of the arc angle and radius of the cylinder on the impedance bandwidth and radiation characteristics of the antenna are extensively studied. The conformal antenna was fabricated on a thin film of Kapton and tested. The measured and simulated results closely resembled each other. 

   more » « less
5. A MIMO Monopole Antenna for Harsh Conditions

   https://doi.org/10.1109/USNC-URSI52151.2023.10238318  

   Mertvyy, Aleks; Razumovskiy, Elesey; Stelmakh, Daniel; Karacolak, Tutku (July 2023, IEEE)

   In this paper, a Multi-Input Multi-Output (MIMO) antenna of 4 monopole elements is presented on Zirconia Ribbon Ceramic (ZRC) substrate. Utilization of this substrate material allows an implementation of an antenna system that is able to withstand harsh environments and high temperatures due to inherent substrate characteristics. The proposed MIMO design supports an operational antenna bandwidth from 2.44 GHz to 2.55 GHz with a center frequency around 2.5 GHz covered by all 4 antenna elements. High antenna isolation below -15 dB is obtained among the ports. The antenna also provides a peak gain over 3 dB through the entire band of interest (3.34 dB at 2.5 GHz) and low cross-polarization. 

   more » « less