Browsing by Author "Sajal, Sayeed Zebaul Haque"

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Conformal Antennas and Arrays with Layers Consisting of Copper and Graphene-based Conductors for Redundancy Properties
(North Dakota State University, 2017) Sajal, Sayeed Zebaul Haque
Graphene is a new promising material with unique electrical, mechanical, optical and thermal characteristics. The use of graphene in the design of an antenna and other electromagnetic passive devices would be beneficial for miniaturization, efficient dynamic tuning, monolithic integration with graphene RF nano-electronics, and even transparency, mechanical flexibility, andreliability. However, there are some challenges to fabricate and design an antenna with pure graphene embedded in the layout. Here, an advanced study on the electrical and mechanical properties of the graphene-based conductive material (not pure graphene), and how this material can be utilized in developing a first-ever graphene-based conformal antenna array for wireless communication systems has been done. More specifically, the important factors for antenna design, such as electrical and mechanical properties, will be studied here to ensure an effective and efficient design. Next, a graphene-based antenna array on a planar surface will be designed to validate the electrical and mechanical properties, and finally, the trade-off of the graphene-based antenna array on a conformal surface is investigated. To mitigate the challenges of designing a graphene-based conformal antenna array, proper care is needed to achieve the optimal performance of the antenna array system. These new mechanisms of the graphene-based conformal antenna arrays will bring new possibilities in conformal antenna usage and wearable antenna applications for the first time.
Low-Cost Passive UHF RFID Tags on Paper Substrates
(North Dakota State University, 2014) Sajal, Sayeed Zebaul Haque
To reduce the significant cost in the widespread deployment of UHF radio frequency identification (RFID) systems, an UHF RFID tag design is presented on paper substrates. The design is based on meander-line miniaturization techniques and open complementary split ring resonator (OCSRR) elements that reduce required conducting materials by 30%. Another passive UHF RFID tag is designed to sense the moisture based on the antenna's polarization. An inexpensive paper substrate and copper layer are used for flexibility and low-cost. The key characteristic of this design is the sensitivity of the antenna's polarization on the passive RFID tag to the moisture content in the paper substrate. In simulations, the antenna is circularly-polarized when the substrate is dry (ϵr = 2.38) and is linearly-polarized when the substrate is wet (ϵr = 35.35). It was shown that the expected read-ranges and desired performance could be achieved reducing the over-all cost of the both designs.