DESIGN AND ANALYSIS OF PLANAR INVERTED-F ANTENNA (PIFA) FOR 5G APPLICATIONS

Abstract

This thesis investigates the PIFA antenna along with some other antennas and the role of periodic structures over the antennas to fulfil the fifth-generation (5G) requirements. The 5G wireless technology is the next step towards the evolution of cellular communication systems. There are three broad categories of 5G bands – the low (600-850 MHz), the mid (3.4-3.6 GHz), and the high (millimeter wave) and all of them have their own pros and cons. The previous wireless technology used the antennas not having high gain, wide bandwidth, and beam steering capability for directional transmission and reception of the signal. However, 5G technology requires antennas with high-speed data rate, high gain for a wide coverage of the network with beam steering capacity (efficient coverage), and should also occupy less area (compactness). To get the high gain required for 5G communications in millimeter frequencies, beam forming technology plays a major role. There are different types of large networks used for beamforming, such as Butler matrix, Rotman lens, phased array antenna because beam steering requires it. However, these methods increase the complexity, weight, and cost of the design. In order to overcome these issues, disruptive beamforming can be used. Disruptive beamforming does not require phase shifters, power dividers to steer the beams. Disruptive beamforming uses some structures like an artificial magnetic conductor (AMC), metasurfaces, superstrate, and RF absorbers through which high gain, wide bandwidth, beam steering can be achieved. Different types of antennas can be used for the purpose of beamforming/beam steering such as monopole antenna, PIFA antenna, microstrip patch antenna, etc. In the second chapter, compact planar inverted-F antenna (PIFA) is designed. It is found that the gain and bandwidth of the antenna are low while the SAR value is high which may not be useful for 5G and other applications. To counter low gain, the gain enhancement of the PIFA antenna is explored by applying AMC and this also helps to reduce SAR. In the third chapter, a coplanar waveguide fed monopole antenna is designed where three superstrate structures have been explored for gain enhancement. The low gain problem is investigated in a systematic manner. Hence, to achieve high gain, AMC is used with superstrate for enhancing the forward radiation from the antenna. Finally, low dielectric superstrate is fabricated with the combination of monopole and AMC.

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In the fourth chapter, beam steering capability is developed in monopole antenna with the help of non-uniform metasurface superstrate and AMC as beam steering with low scan loss is going to be a necessity for 5G communications. In the fifth chapter, Eccosorb MCS absorber is used which is used to transform the radiation pattern of a slotted PIFA and producing a radiation beam in the desired direction while also increasing the antenna's gain. Extending the work in the fifth chapter, we designed a planar inverted-F multi-beam antenna using RF absorbers in the sixth chapter. The proposed antenna provides multiple beams from a single antenna with wide angular coverage. The designed antenna achieves a multi-beam behaviour by six slabs of absorbers placed periodically between the PIFA patch and substrate. In the seventh chapter, circular polarized MIMO antenna for the 5G band is designed. The MIMO antenna incorporates SIW structure which is used to perform beamforming. The eighth chapter conclude the work and future scope of the thesis. In this way, this thesis will discuss gain enhancement, beam splitting, and beamforming techniques using AMC, superstrate, RF absorbers, and metasurface superstrate with different antennas.