A multiband fractal co-planar waveguide (CPW)-fed slot antenna loaded with a dielectric resonator conforming to multiple wireless standards is presented in this paper. The Minkowski fractal geometry is utilized to generate multiple frequency bands as well as to provide a miniaturized design compared to its Euclidean counterpart. The idea behind placing the dielectric load is to serve a dual purpose of enhancing the impedance bandwidth of the antenna at the upper frequency band as well as improving the overall gain of the antenna. The slot loop acts as a hybrid antenna performing the task of both an antenna as well as a feed mechanism for the dielectric slab to radiate. Design guidelines involving closed form formulae and equivalent model consisting of lumped resonators, distributed resonators and impedance transformers of the dielectric-loaded fractal slot antenna are provided to present an insight into the functioning of the antenna. The reflection coefficient parameters of the antenna yield a close match between the circuit model and those obtained from full wave simulator. The proposed antenna exhibits a heptaband performance with a maximum gain of 3.1 dBi.

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).

The realisation of an electronically tuned polarisation reconfigurable dielectric resonator antenna with multiple switchable states is described in this study. The antenna is fed by a microstrip line through a cross‐slot aperture placed in the ground plane to achieve circular polarisation. PIN diodes have been placed across the cross slots to control their effective dimensions and thereby its sense of polarisation. The antenna is connected to a microcontroller (ARDUINO‐UNO) to switch between corresponding polarisation states. Simulated results of the antenna are verified with experimental data. The antenna has an impedance bandwidth of about 20% for all four states of polarisations. The antenna also radiates with a gain of 4 dB over the entire band.

This paper deals with miniaturization of wearable electro-textile antennas by the use of Minkowski fractal geometries. Two electro-textile materials namely Flectron and Zelt are considered for the design of flexible microstrip antennas. In both cases, polyester fabric material has been employed as dielectric medium. In the basic design both the antennas are designed for WLAN applications. The Flectron antenna provides a gain of 6.54 dB with an impedance bandwidth of 132 MHz whereas, the Zelt antenna offers a gain of 7.4 dB and an impedance bandwidth of 104 MHz. By applying Minkowski fractal geometry to the antennas, miniaturization is achieved. In its first iteration, antenna designs are optimized and tuned to WiBro band and in the second iteration, antennas are further miniaturized in order to make them suitable for GSM 1900 applications. In these two bands, the gain and efficiency of both Flectron and Zelt antennas conform to their respective wireless standards. The simulation studies reveal that Zelt antenna yields better results compared to Flectron antenna.

Two arms of double-sided printed dipole antenna (DSPDA) are printed on opposite faces of a dielectric material. The antenna is fed by the printed version of two-wire parallel transmission line. This configuration has the advantages of high impedance bandwidth and low cross polarization. The width of each dipole arm is generally kept below 0.05(0) to achieve high cross polar discrimination. However, it is observed that, in case of DSPDA the resonating length is different from that of the conventional half-wave dipole antenna. In this paper, we have proposed a semi-empirical but accurate formula to predict the resonant frequency for a given length of DSPDA. A prototype antenna is fabricated using the proposed formula which is validated against experimental results. Measured resonant frequency of the fabricated DSPDA matches closely with the theoretical one.

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.