Wireless communication has become ubiquitous and indispensable in modern society. The latest amendment of WLAN communication standard, IEEE 802.11ax, provides capabilities to efficiently utilize the unlicensed spectrum band (2.4 and 5GHz) and improve user experience. The new features in IEEE 802.11ax arise from novel system technology, but the gains from these are reaching fundamental limits. Further enhancements are possible through leveraging technologies such as phased array and advanced reconfigurable antenna. Specifically, beam-steerable antenna could greatly enhance the wireless systems since it can be used to increase SNR, reduce signal distortion, avoid interference, promote security and save power.

In this thesis, digital highly reconfigurable antenna technique is explored to...[ Read more ]

Wireless communication has become ubiquitous and indispensable in modern society. The latest amendment of WLAN communication standard, IEEE 802.11ax, provides capabilities to efficiently utilize the unlicensed spectrum band (2.4 and 5GHz) and improve user experience. The new features in IEEE 802.11ax arise from novel system technology, but the gains from these are reaching fundamental limits. Further enhancements are possible through leveraging technologies such as phased array and advanced reconfigurable antenna. Specifically, beam-steerable antenna could greatly enhance the wireless systems since it can be used to increase SNR, reduce signal distortion, avoid interference, promote security and save power.

In this thesis, digital highly reconfigurable antenna technique is explored to address the challenges in WLAN wireless communications. Firstly, a new planar pattern-reconfigurable antenna for IEEE 802.11ax applications is described. The feeding structure and main radiators are designed to provide an impedance bandwidth of 4.6 to 6.0 GHz while a reconfigurable beam-width of 300° in the azimuthal plane is implemented with optimized parasitic elements. The maximum achievable gain is close to 10 dBi and efficiency is measured to be 70%.

Secondly, the reconfigurable antenna technique aimed at MIMO applications is investigated, including the appropriate layouts of the structure and derivations of the multiport impedance network algorithm. Similar to the single-port version, a dual-port beam-steering antenna prototype is fabricated and the test results show that return losses lower than -10 dB and a mutual isolation of at least 15 dB has been satisfied for both ports across the frequency range of IEEE 802.11ax. Average antenna gain and total efficiency are measured to be 7 dBi and 65%, respectively, and a beam-scanning coverage of 300° can be realized.