Theses and Dissertations

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    ItemOpen Access
    Compact Circularly Polarized Tri-, Dual- and Single-Band Dielectric Resonator Antennas
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2021) Chaudhary, Pankaj Prabhubhai; Ghodgaonkar, Deepak K.; Gupta, Sanjeev
    The Dielectric Resonator Antennas (DRAs) have received wide attention due to low loss, high radiation efficiency, small size, wider bandwidth and simple feed network as compared to the microstrip antennas. Microstrip antennas have many challenges such as low radiation efficiency, high conductor loss, poor polarization purity, multiple frequency bands and multiple polarizations with a large footprint area of the antenna, low gain and narrow bandwidth. The existing design techniques for tri-, dual- and single-band DRAs reported in the literature have various limitations such as ground plane area of DRA, volume of Dielectric Resonator (DR) and DRA not sufficient for small physical area applications, realization of Circular Polarization (CP) over large ground plane area and unavailability of single DR geometry with multi-mode for multi-band applications. In this thesis, compact CP tri-band (L5, L1 and S-bands) staired Rectangular Dielectric Resonator Antennas (RDRAs) (two port, single port) using tri-, dualand single-sections Wilkinson Power Dividers (WPDs) with wide-band 90◦ phase shifters are designed, analyzed, fabricated and tested. These tri-band RDRAs are used in Indian Regional Navigation Satellite System (IRNSS) and GPS-Aided GEO Augmented Navigation (GAGAN) applications. The ground plane footprint areas of tri-band RDRAs and volumes of staired Rectangular Dielectric Resonators (RDRs) are significantly reduced by using high dielectric constant of DR materials and high dielectric constant of dielectric substrates. The broadside radiation patterns of triband RDRAs are produced by TEy 111, TEy 113 and TEy 112 modes for L5, L1 and S-bands, respectively. Various parameters of tri-band RDRAs like return loss, Right Hand Circularly Polarized (RHCP) - Left Hand Circularly Polarized (LHCP) radiation patterns, RHCP gains and axial ratios are analyzed and measured. Compact CP dual-(L5 and L1) and single-band RDRAs are designed, analyzed, fabricated and tested using feed networks of dual- and single-sections WPDs with wide-band 90◦ phase shifters. The miniaturized volumes of RDRs and ground plane areas of dual- and single-bands RDRAs are achieved using high dielectric constant of DR materials and high dielectric constant of dielectric substrates. The broadside radiation patterns of dual-band RDRA are produced by TEy 111 and TEy 113 modes for L5 and L1-bands, respectively. The TEy 111 modes are produced in three single-band RDRAs for L5, L1 and S-bands. The simulated and measured parameters of dualand single-band RDRAs are return loss, RHCP-LHCP far field radiation patterns, RHCP gain and axial ratio. The design and analysis of finite ground plane single-band CP RDRAs using WPD with wide-band 90◦ phase shifter for L1 and L5-bands are carried out by using high dielectric constant of DRs and dielectric substrates. Also, the effect of different radii of finite circular ground planes of single- and dual-band RDRAs are investigated by using the Method of Moments (MoM). The effect of different radii of circular ground plane on single- and dual-band RDRAs are analyzed for return loss and gains.
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    ItemOpen Access
    Novel circular fractal antenna array
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2018) Chauhan, Rahul; Gupta, Sanjeev
    Traditional antennas work well only for one resonant frequency and using multiple antennas for different frequencies is a complex task, therefore multiband circular fractal antenna was designed which have a small size and multiple resonating frequencies for UltraWideband Applications (UWB). For designing and fabrication of the antenna the substrate used is FR4 which have dielectric constant 4.4 and whose dimensions are 48 96mm2. For the excitation of the antenna microstrip feed line of 50W is fed to the circular fractal patch for impedance matching. The UWB characteristics can be achieved using fractal concept. Also to increase the bandwidth, slots of different dimensions are etched out from the ground plane from the basic fractal configuration. Slots dimensions are adjusted in each iteration to achieve the desired results. In the later part of the work, different array configurations of the circular fractal antenna are analyzed. The various arrays design configurations are 1 2, 1 4, 2 2 and 2 4. The substrate used is FR4 whose dimension is varied according to the array configurations. Similar to basic antenna design a 50W microstrip feedline is used to excite the antenna for all the configurations. The antenna shows stable radiation patterns and good return loss values i.e better than 10dB at multiple frequencies. All the analysis is done in HFSS 2014.
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    ItemOpen Access
    Radiation analysis of microstrip active (amplifier) and passive (antenna) structures
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2010) Dhoot, Vivek; Gupta, Sanjeev
    Analysis of radiation from a microstrip amplifier and a newly proposed microstrip antenna is presented. Microstrip amplifier is analyzed replacing the MMIC structure by an equivalent S2P model and remaining portion being constructed with the original dimensions. A printed monopole antenna using multifractal technique is proposed. This antenna has multiband characteristics covering various wireless applications including WLAN 2.4 GHz and 5.8 GHz applications