Printed Monopole Antennas with multiple bends for rfid wlan and UWB Applications

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Printed monopole antenna (PMA) with the microstrip feed line are an important class of broadband antennas. Because of the stripped ground plane on the back side of the substrate, these classes of antennas provide large bandwidth. Dual band operation can be achievable for these classes of antennas by creation of two independent resonating paths in the form of protruding stub in the ground plane and the radiating element printed on the top of the substrate. The major challenge in designing these antennas is the tuning of the protruding stub in the ground plane with the radiating element on the substrate to provide the dual-band operation for RFID, WLAN, etc. These antennas are light weight, low profile, less fragile and easily integrable with the hand held devices. UWB antennas are wideband antennas (3.1-10.6 GHz), widely used for application in modern wireless hand held devices. Miniaturization is a major challenge for the design of these UWB antennas. Apart from the compact size, consistent omni-directional radiation pattern, appropriate gain characteristics and suitable time domain characteristics are needed for designing a proper UWB antenna. In the UWB frequency region of 3.1-10.6 GHz, many narrowband wireless systems exist such as WiMAX (3.3-3.6 GHz) and WLAN (5-6 GHz), which interferes with the UWB operation. Hence, these narrowband wireless systemsD spectrum should be notched up for coexistence of UWB with the other existing narrowband devices. In our work, we have designed, simulated, fabricated and tested PMAs with multiple bends for applications in RFID, WLAN and UWB systems. Antennas are categorized depending upon the number of bends either in the radiating element or in the protruding strip in the ground plane. In this work, single, double, triple and quadruple bend PMAs for the dual-band WLAN and RFID applications are proposed. It has been observed that our proposed novel PMAs are considerably better than the existing planar antennas in terms of size compactness, bandwidth improvement and gain enhancement for dual band RFID/WLAN operations. Besides, rectangular PMA with multiple bends in the feed region with appropriate time and frequency domain characteristics, are proposed for single- and double-notched UWB communications for coexistence of UWB devices with other narrowband devices viz., WIMAX and WLAN. Keywords: Bend, F-shape, inverted L-strip, monopole antenna, protruding stub, UWB, double notch UWB PMA..
Supervisor: K. Rakesh Singh