Wideband ceiling mount omnidirectional antenna for indoor distributed antenna system applications

A wideband omnidirectional vertical polarised antenna is presented. By incorporating a shorted coupling top loading structure over two cross-connected monopole antennas, an enhanced impedance bandwidth of 152% is achieved. The prototype antenna operates from 650 to 4500 MHz, with a reflection coefficient <;-15 dB, a 2-6 dBi antenna gain with a very stable vertical radiation pattern and <;3.5 dB horizontal pattern ripples. The proposed antenna can be widely used in indoor distributed antenna systems (DASs), such as GSM900, GSM1800, UMTS2100 and the enhanced TD-LTE (up to 3.5 GHz) bands. The simulated and the measured return loss and radiation pattern results show good agreement.