Investigations on Printed UWB Antennas for Indoor High Data Rate Communications

Abstract

Wireless communication is becoming a necessary component for modern living. The communication limitations have been completely removed with the introduction of wireless communication. Wireless communication has provided us with a variety of time-saving opportunities. Wired gadgets have been replaced with cordless ones. Wireless devices with bigger antennas have been replaced with smaller antennas. Bluetooth, Wi-Fi, and WPAN are examples of wireless networking technologies that have improved connectivity for portable devices. The need for high-speed communications continues to increase day by day as people's requirements increases. UWB technology is an ideal method for achieving high data rate transmission. Ultra￾Wideband (UWB) technology has emerged as a transformative wireless communication paradigm with broad-ranging applications across industries. The ultra-wideband radio spectrum, often known as UWB or ultra-band, is envisioned for short-range high-bandwidth communication. Ultra-Wideband (UWB) technology has garnered significant attention due to its ability to transmit and receive signals over an extensive range of frequencies with low power consumption. Since the 7.5 GHz frequency spectrum from 3.1-10.6 GHz opened for use, the field of ultra wideband communications has expanded due to its many inherent benefits, which include high data rates, low average power consumption, reduced susceptibility to multipath revocation, improved range accuracy and low cost. The key difference among UWB and traditional radio transmission is that the traditional one transmits data by altering the frequency, phase, or power level of a sinusoidal wave, while the UWB transmits data by creating radio pulses at specific time intervals and occupy an enormous bandwidth. Because the system uses power deficit, short bursts of radio signals, it has much less interference than other narrow band systems, so it can coexist with other narrow band conventional wireless technologies that already exists, such as Bluetooth, WLAN, and Wi-Fi. However, extremely strong interference may result from narrow band systems when located very close to a UWB system. This imposes very strict limitations on the linearity and filters of the UWB frontend. Thus in order to lessen the interference, a notch at the interferer frequency is necessary. All this led to the motivation behind this thesis work.This thesis aims to accomplish four objectives: all the designs are segregated with respect to the objectives achieved. The first and second designs are based on first two objectives, the first objective is to analyse and design UWB antenna and the second objective is to implement the notch characteristics in UWB antenna. The first design is an infinite length slotted UWB antenna achieved 2.5 ~ 12 GHz bandwidth, exhibiting notch characteristics for 3.5 GHz. The design is fabricated on a cost-effective FR4 substrate. The second design is a step feed Ultra-Wideband quarter elliptical monopole antenna exhibits band notch characteristics at 5.8 GHz. Two inverted L-shaped slots, accompanied by a pair of circular slots are carved on the area of the patch for band notch features. The third objective is to design and implement a novel tapering technique for proposed UWB/notched UWB antenna. The proposed antenna is squiggly shaped tapered feed antenna. This antenna is two-layered, in which one layer is of dielectric material and the top layer is a copper layer containing a circular patch, CPW-fed tapered feed. The measured impedance bandwidth is extended to 20.3 GHz ranging from 3.3 GHz. The designed antenna is made by a uniquely designed tapered feed circular patch antenna excited through a CPW feeding mechanism. The proposed antenna design is a novel as no one has ever proposed a squiggly shaped tapered feed. The fourth objective is to design and implement a DR-based antenna. The two different DR￾based antennas were designed on this objective. In the fourth design, the antenna is a QWT based CDRA is obtained by pasting the cylindrical DR on the FR-4 substrate having QWT feedline used for excitation and DGS at the back as ground. The antenna presented in fifth design is a QWT based RDRA which is obtained by pasting the rectangular DR on the Arlon AD255C rogers substrate having QWT feedline used for excitation and defected ground structure (DGS) at the back as ground. Both the fourth and fifth designs are patch-less DRA antennas.