An Ultrawideband MIMO Antenna With Dual Band-Notched Function

Abstract

A new technique to achieve both good isolation and dual band-notched functions for ultrawideband (UWB) multiple-input-multiple-output (MIMO) antennas was developed. The proposed antenna consists of the radiation patch connected through a via with the strip placed beneath the patch. The strip not only provides another coupling path, but also serves as the impedance transformer, resulting in good isolation (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> <; -15 dB) and dual band rejection at WiMAX (3.4-3.7 GHz) and WLAN (5.15-5.35 and 5.725-5.825 GHz) over the UWB system operation (3.1-10.6 GHz). Without decoupling element or resonator, which is often placed between the antennas to acquire good isolation or band rejection, the proposed UWB MIMO antenna requires an individual antenna element size of only 11.2 12 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (0.12λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.11λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> )and overall MIMO antenna size of 30 40 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (0.31λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.41λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ). The edge-to-edge separation between antennas is , and separation between feeds is 0.175λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 3.1 GHz. Detailed investigations of the parameters were performed, and the experimental results agree closely with the simulation results, demonstrating the feasibility of the proposed method.