Optimization Design of Isolation for a Dual-band Dual-port Antenna

This paper presents a dual band dual port microstrip array antenna which consists of two parallel rectangular patches. A rectangular slot is created on the larger size patch corresponding to the low frequency band, and the small patch corresponding to the high frequency is integrated into the slot. The nested structure brings serious coupling between two ports, and the mutual coupling is one of the main factors that affect the performance of array antenna. In order to improve the mutual coupling of the nested parts, two parallel microstrip lines connected by a grounded disk are loaded between the two radiation patches to reduce coupling current, and two slots located on the vertical edges of the nested small patch further reduce the coupling current to improve isolation. After the optimization design, the final isolation of the antenna in the working band is greater than 20 dB. The working bands of the proposed antenna are 15. 2 GHz and 5. 8 GHz, the maximum gains in two bands are 7. 8 dBi and 6. 8 dBi. The two patch sizes of the proposed antenna are respectively 0. 36λ(15. 2 GHz) and 0. 37 λ(5. 8 GHz), and the radiation patches are nested in each other which meet the requirements of miniaturization design.