A high-gain, wide-beamwidth, six-loop-antenna MIMO system suited for wireless access points in the concurrent WLAN 2.4 and 5 GHz bands is presented. The antenna system mainly comprises an antenna ground plane and single-band loop antennas, among which the three antennas are designated for 2.4 and 5 GHz operation respectively. The antennas are set in a sequential, rotating arrangement on the ground plane with an equal inclination angle of 60° to form a symmetrical structure, and the 2.4 and 5 GHz loops are facing each other one by one. The experimental results show that good port isolation can be obtained between antenna ports. High-gain, directional radiation patterns with wide 3-dB beamwidth in elevation planes are also observed. Details of a design prototype are described and discussed in the paper.

1. Concurrent 2.4/5-GHz Multi-Loop MIMO Antennas with Wide 3-dB Beamwidth Radiation for Access-Point Applications * Saou-Wen Su, Ph.D. Network Access Strategic Business Unit Lite-On Technology Corp., Taipei, Taiwan *E-mail: stephen.su@liteon.com

5. MIMO AP/Router on the Market More and more antennas required From dual-radio to concurrent dual-band D-link wireless N series U4EA Fusion 50 HiveAP 300 series

7. Concurrent Dual-Band Antennas 1 US patent no. 6535170 B2, Mar. 2003/Sony Corp. single-feed, dual-band antenna: achieve concurrent operation by adding extra diplexer component two-antenna system is self-diplexered

8. Concurrent Dual-Band Antennas 2 US/TW/CN patent pending swivel-type AP antenna coaxial cable is arranged to first go through monopole ground and then center of dipole ground MOTL, vol 51, May 2009 bottom end two coaxial cables in two-antenna system can affect mutual coupling between antennas

12. Design Consideration 2- Design example US/TW/CN patent pending MADE of a 0.4-mm-thick alloy plate with only one set of mold for tooling; the ground can be circular as long as 6 loops are set thereon symmetrically

17. Related Designs 1- Dual-band single-radio antennas MOTL, vol 50, May 2008 IEEE AP, to appear in 2010 BW: 2400-5850 MHz (10 dB RL); isolation < – 20 dB 2.4 and 5 GHz bands (10 dB RL); isolation < –15 and –20 dB over the 2.4 and 5 GHz bands

18. Related Designs 2- Dual-band dual-radio antennas very-low-profile < 6 mm; isolation < – 15 and – 20 dB over the 2.4 and 5 GHz bands for high-gain, short-circuited AP antennas; isolation < – 25 dB MOTL, vol 51, Nov 2009

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