A Reconfigurable Multiband Monopole MIMO Antenna with Wideband Sensing Capability for Cognitive Radio

• Main Authors: Shuo-peng Cheng, 鄭碩鵬
• Other Authors: Ken-Huang Lin
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/04928024500876707688

碩士 === 國立中山大學 === 電機工程學系研究所 === 103 === Recently, radio spectrum is in high demand as the usage of the spectrum increases day by day at an enormous rate; there is a need to find a solution to efficiently utilize these insufficient resources. Cognitive radio is a huge step towards this goal. Cognitive radio has become a promising technology thanks to its inherent spectrum sensing capability and frequency-agile radio functions for efficient spectrum utilization. In order to achieve a cognitive radio antenna system, we have to design a frequency reconfigurable antenna and a wideband sensing antenna. On the other hand, a multiple-input-multiple-output (MIMO) antenna system is a well-known technique to enhance the performance of wireless communication systems. Quite a few research has been available in each individual field but very few approaches are found in literature where both are combined and utilized. A cognitive radio MIMO antenna is presented in this paper. The proposed antenna consists of two reconfigurable printed monopole antennas and a coplanar waveguide (CPW) fed wideband sensing antenna located between the two antennas. The structure is specially designed for antenna miniature. For multi-channel wireless communication systems, it is essential that the designed multi-antenna would have high isolation between the antenna ports. To this end, the wideband antenna at the middle is utilized as a structure to enhance the isolation of two monopoles. When properly designed, the MIMO antenna can be electronically tuned over the lower ultrawideband (UWB) frequency band (2300–6300 MHz) using two pairs of varactor diodes. The wideband sensing antenna is used to cover a wide range frequency band from 2.2 GHz to more than 7 GHz. The proposed antenna elements develop a complete antenna platform for cognitive radio (CR) applications. The overall size of the antenna is set to be 60 × 40 mm2.