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Simulation, Design and Transient Analysis of Spark-gap Integrated Dipole Antenna for Optimum PerformanceAuthor: Ratan Sanjay Doma Date: 2022-02-25 Report no: IIIT/TH/2022/14 Advisor:Azeemuddin Syed AbstractToday’s society cannot be visualized without the dependency of humanity on technology. Every walk of life in human survival today is linked to computers and electronic systems, which undoubtedly improve the quality of life. This comfort comes with a restriction because of the vulnerability of the electronic system to anti-electronic threats. Not orienting towards offensive, it is indeed the need of the hour to protect our systems by characterizing their susceptibility levels. Many researchers formulate the threat scenarios, and international committees constituted for this purpose. High power electromagnetic (HPEM) systems that could generate and radiate few gigawatts were developed worldwide. Likewise, an antenna also plays a crucial role in the HPEM systems in any transmitting system. However, there are more challenges in designing and developing antennas for HPEM systems. Among the categories of antennas developed for this purpose, wideband/Ultra-wideband (WB/UWB) antennas that are capable of transmitting transient impulse-like high voltage signals are potential contenders. A well-designed WB/UWB antenna should have high fidelity in transmitting the transient signal without altering its characteristic parameters. This thesis focuses on the design, analysis, development, and measurements of a wideband antenna, spark gap integrated dipole (SGID) antenna. The main focus is placed on transient analysis, its construction, and performance evaluation. Spark gap integrated dipole (SGID) are simple in construction, compact, and reliable transient wideband antennas for high power applications. They offer the promise of utilizing them to very high powers without any complications and can easily be fabricated with low-cost materials. This makes them a viable alternative to complex horn-based antennas that are generally used in high-power scenarios. Despite the aforementioned advantages, the bandwidth offered by these antennas is limited to mesoband, whereas Transverse Electromagnetic (TEM) based horn antennas can scale up to hyper bands. As a result, their use is limited to Directed Energy Weapon (DEW) applications that demand damped sinusoidal radiation and, to some extent, in UWB radars. While horn-based antennas have matured technology, both experimentally and theoretically, only a few researchers have reported the analysis of spark gap integrated dipole antennas. In this thesis, we mathematically modelled the SGID antenna based on Maxwell’s equations, and a theoretical transient response is generated. The performance of SGID is thoroughly analysed using computational electromagnetics for its transient response. The physical dimensions of the dipole are optimized for maximum radiation efficiency. The spark gap efficiency was also studied by evaluating the performance for various electrode profiles. Modifications are proposed to the existing designs in order to enhance the performance and increase the figure of merit. This includes optimal dimensions visà-vis input signal parameters which help not only for the maximum radiation but also its spectral occupancy. In addition to this, the selection of Bruce’s profile has ensured uniform electric field distribution and has allowed using the dipole for higher voltages. To further enhance the reliability of the antenna, hydrogen gas is selected as the spark gap medium due to its high recovery rate property. These proposed methods are mathematically formulated, simulated, and analyzed, and a considerable improvement in the overall SGID performance is reported. The theoretical analysis is validated by measurements by subjecting the antenna to a 100kV pulsed input voltage. A logical measurement procedure is proposed that removes the ambiguity in measurements as the radiation from the spark gap antenna is highly probabilistic. The proposed design and development methodology of the SGID has resulted in an efficient transient radiator with a figure of merit (FoM) significant compared to those reported in the literature. Full thesis: pdf Centre for VLSI and Embeded Systems Technology |
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