This paper presents the design of a quad-port orthogonal ultra-wideband (UWB) monopole antenna backed with an electromagnetic band gap (EBG) structure. The EBG structure provides band stop/band reject characteristics in the entire UWB range. The overall dimension of the diversity antenna is 70 × 70 × 1 m m 3 ( 0.68 λ 0 × 0.68 λ 0 × 0.01 λ 0 ), where λ 0 corresponds to the lowest resonating frequency. The proposed monopole antenna offers good impedance bandwidth of 8.67 GHz (2.93-11.6 GHz). The estimated diversity characterization metrics observed over the obtained frequency range are envelope correlation coefficient < 0.11, mean effective gain (MEG) < 1 dB, effective diversity gain < 9.88 dB, apparent diversity gain < 9.99 dB, channel capacity loss < 0.19 bits (s Hz)−1, and total active reflection coefficient < −20.95 dB. Also, specific absorption rate analysis is realized for the antenna in seven different tissues of the body (forehead, forearm, upper arm, chest, abdomen, thigh and lower leg) to check radiation exposure towards the human body.