Ultra-wideband design of sleeve monopole antenna

Recently, ultra-wideband (UWB) communication system is becoming attractive for high-capacity wireless communications applications. UWB systems have been allocated to the frequency band of 3.1 to 10.6 GHz (3.4:1 bandwidth ratio). To meet the UWB bandwidth requirement, the search for antenna configurations with the wide operation bandwidth has been a dominant feature of the system performance. Sleeve monopole antennas have been demonstrated with a broadband characteristic . However, the impedance bandwidths for these related designs are generally less than 2:1, which is obviously inadequate in UWB systems. In this paper, we present a simple CPW-fed sleeve monopole antenna. The proposed antenna is particularly simple in manufacturing owing to its single metal layer and no via hole required in short circuiting the sleeves to the ground plane. In addition, this antenna can achieve very broadband impedance behavior. Its bandwidth far exceeds the achievable bandwidths using conventional sleeve monopole antennas. Details of the proposed design and obtained experimental result are presented and discussed.