Kaushik Patra

Multiport network model (MNM) of microstrip patch antennas is an extension of cavity model analysis. In MNM, electromagnetic fields present under and outside patch are modeled separately and the patch is considered as a planar element with multiple ports at its edges. The MNM approach was previously used for the analysis of different patches such as rectangular and circular. However, MNM analysis for irregular‐shaped hexagonal patch antenna is not studied yet. Analysis of hexagonal patch antenna is required for its several advantages over other patches such as equivalent surface current distribution with less size compared to circular patch and higher bandwidth. In this work, the irregular‐shaped hexagonal patch antenna is analyzed using MNM technique. The antenna is decomposed into rectangular and right‐angle triangular segments. Multiport impedance (Z) matrices are calculated for all elements based on Green’s functions of corresponding shapes. Finally, the current distribution of the complete patch is obtained by connecting these elements using Z matrices. The irregular‐shaped patch antenna is fabricated, and its responses are measured to verify the results obtained from MNM analysis. MNM can estimate antenna performance with ~3.5% average error with respect to simulated responses in terms of antenna performance parameters.

Shielded wires are widely used in electric and hybrid electric vehicles. Estimation of the radiated emissions from these cables require an appropriate description of the transfer impedance. The Kley Model describes this transfer impedance analytically as a function of geometrical parameters of the shield. The shield parameters are too intricate to be characterized and specified in datasheets, hence, the parameters have an uncertainty associated with them which does not allow unique modelling of the cable. These uncertain parameters generally influence the radiated emission characteristics of a given cable. Conventional techniques to analyze the parameters' impact are usually through several simulations or measurements based upon certain approximations of the uncertain parameters. In this article, we use Polynomial Chaos Expansion to construct a surrogate model of the radiated field in the frequency range from 10 MHz to 1 GHz as a function of all geometrical parameters of the shield. Surrogates are developed for Shielded Twisted Pairs and coaxial cables. We subsequently use the developed surrogate models to study the impact of variations of the shield parameters on the radiated electric fields.

This work presents a novel technique for miniaturization and bandwidth enhancement of a Rectangular Microstrip Antenna (RMA) operating at higher order TM03-like mode. The resonant length of a conventional RMA supporting the TM03 mode is reduced by λ/4 (λ is the operating substrate wavelength) by this design at the operating frequency. Consequently the conventional resonant length of 1.5λ for this mode is reduced to 1.25λ. Excitation of this TM03-like mode increases gain as well as antenna efficiency at the design frequency of 5.8 GHz. A wide slot is placed on the patch to reduce the side-lobes of the radiation pattern. Three meandered line linkages are placed inside the slot to miniaturize the structure maintaining current continuity. Resonance behaviour of the antenna is studied using Theory of Characteristic Modes and the impedance bandwidth is enhanced by controlling the excitation of the next higher order mode in the vicinity of TM03-like mode by appropriately choosing dimensions of the meander lines. The antenna is fed by a coaxial probe and is easy to fabricate. Measurement shows an impedance bandwidth of 8.5% and a peak gain of 10.5dBi. The overall size of the designed antenna is 1.31λ0λ1.31λ0λ0.03λ0 (λ0 is free-space wavelength at 5.8 GHz).

A single layer simple feed reduced side lobe gain-enhanced microstrip antenna array using higher-order modes is analyzed and designed in this work. The relationship between the relative magnitude of equivalent magnetic currents and directivity are studied. Modal analysis for rectangular patch is considered for broadside and non-broadside radiation. Comparative investigations on antenna radiation and impedance characteristics for fundamental and higher-order modes are presented. It is observed that an array can be designed to operate in TM(03)mode for enhanced gain with broadside radiation. Parametric optimization is carried out to attain low side lobe level. The proposed theory is validated by designing and fabricating a single layer single feed 2 x 2 microstrip patch array in the K band operating in TM(03)mode. The simulated and measured realized gain of the fabricated TM(03)mode array is 16.1 and 15.5 dBi, respectively, at 22 GHz with consistent broadside radiation pattern and linear polarization.

Propagation channel characterization and modeling is an important aspect in wireless communication domain prior to design and implementation of any RF system especially in mmWave band for 5G ecosystem. Several methods have been proposed in the literature for different environments where the antenna effects present inherently in the measured results caused ambiguous channel characterization and model. The results are antenna specific and unreliable for other antennas. In this work, the standalone channel response (frequency and time domain) excluding the antenna effects has been derived using a two port network approach. Identical horn antennas operating in C band have been used to measure the channel transfer function and impulse response. A comparative investigation of the measured results with and without antenna effects is presented. It is observed that measuring channel characteristics without excluding the Transmitting and Receiving antenna effects adds additional time delays and reduced coherence bandwidth of the channel.