Dual-band Patch Antenna Design with Pattern Diversity

In this paper, a novel design of a dual-band dual-mode slotted circular patch antenna design has been proposed. The differential and common mode feeding of the slotted patch are utilized to excite the two modes having broad-side and omni-directional radiation characteristics. A Wilkinson Power Divider is used to feed the slotted patch antenna for 180 and 0 degrees phase shift at the lower and upper-band respectively. The proposed antenna operates in two frequency bands centered at 3.31 GHz (Impedance Bandwidth=4.80%, Broadside pattern) and 5.86 GHz (Impedance Bandwidth=6.87%, Omni-directional pattern). The electrical size of slotted patch along with the feed network is $0.73 \lambda \times 0.55 \lambda \times 0.44 \lambda$ ($\lambda$ corresponds to 3.3 GHz). The array of four slotted patches are further arranged in a $2 \times 2$ configuration to arrive at the design of pattern and spatial diversity multiple-input multiple-output (MIMO) antenna system. The ports of the MIMO system have isolation level better than −20 dB, while the far-fields show an envelope correlation coefficients (ECCs) lower than −22 dB in both the operating bands of antenna. The performance characteristics of the single and $2 \times 2$ antenna elements have been validated by measurement carried out on their fabricated prototypes.