Printed Sleeve Monopole Antenna

Abstract

Sleeve antenna dates back to 1947 with its applications in high frequencies by [Bock 1947]. A series of consequent designs and rigorous analysis for such kind of antennas was extensively carried in the preceding years [Norgorden, 1950, King 1965, Poggio, 1966]. Furthermore, [Rispin, 1988] discussed thin-wire analysis for sleeve antennas by studying the standing wave current on the antenna surface. The impedance and pattern of the sleeve monopole antenna was studied in detail by [Wunsch 1998] with the help of Fourier series representation of its surface current. Since then, sleeves have widely been used in multiband communication systems to achieve multi-resonances, miniaturization and wide impedance bandwidth. The sleeve, when applied as extension of ground plane behaves like an additional parasitic element that generates extra resonant mode. The additional resonant mode offered by the sleeve can either be used for dualband/multiband operation or if the extra mode is in close proximity then it combines with the fundamental mode to improve overall bandwidth. On the other hand, ground shorted inset sleeve leads to formation of a virtual feed to excite low resonant mode and is simple tool for antenna miniaturization. Although UWB antennas have been the interest of engineers over the decade but the recent attraction in the design of such antennas was initiated after the official bandwidth allocation by (FCC, 2002). In addition, after the growth of telecom industry, more and more high speed devices are emerging in the competitive telecom markets with many different built in communication systems working at different frequencies requiring more and more bandwidth to perform those operations. This requires antennas with ultra-wide impedance bandwidth. On the technical side, UWB systems provide high data rates along with large channel capacity, immunity to multipath interference, low complexity, low power consumption and coexistence with other wireless systems [Zhong, 2010]. The real efforts toward UWB antenna design started when [Honda et. al., 1992] proposed a circular disk monopole antenna for the first time to be used for indoor TV systems in Japan. After that, several novel techniques have been introduced by many researchers to achieve ultra widebandwidth requirement. The traditional method is to use a thicker substrate with small relative permittivity substrate. The thickness and permittivity of the substrate is comparison among its availability, usage and price. Therefore, it is not an open choice for the antenna designer. Although, the thicker substrate can improve the impedance bandwidth up to 10%. However, the surface waves are generated for thicker substrate and degrades antenna performance. The other methods include use of different shapes of radiator, optimization of