Design of a Barque-Shaped Two-Port MIMO Antenna with Enhanced Isolation Characteristics for WLAN Applications

In this work, a compact two element MIMO consisting of a Barque-shaped antenna structure (BSA) is proposed for WLAN applications. The two element MIMO resonates at a 5.2GHz frequency. This structure was designed by using a pentagon patch with a V-shaped asymmetrical slot etched from the patch and an L-shaped DGS (Defective Ground Structure) for higher isolation improvement. The overall proposed antenna occupies a size is 44x32x1.6m3. The proposed structure uses a Rogers RT5880, which has a dielectric constant of epsilon r is 2.2. In this design, a U-shaped feed line is used for impedance matching. Initially, a two-element MIMO without DGS was developed, but the required isolation values were not achieved. To enhance isolation, a sequence of opposing L-shaped slot DGS structures is employed in series. The two radiating elements are separated by 1.8mm. It is taken into consideration that there is very short spacing. The antenna performance analysis parameters such as S-parameters, radiation patterns, and surface current distributions, and the MIMO antenna performance parameters are also studied, such as DG (Diversity Gain) and ECC (Envelope correlation Coefficient). The gain is achieved at the desired frequency and is 5.26dB. Without DGS, the S11 measures -14.15dB and the S21 measures -16.56dB. With L-shaped slot DGS, the S11 measures 18.38dB and the S21 measures 32.18dB. As a result of the observations, the isolation has been enhanced in doubles (-32.18dB). The proposed MIMO antenna has a simple structure and is well suited for WLAN applications. The proposed two element MIMO antenna S-parameter was measured using both the MITS eleven lab and the Rohde & Schwarz ZVL vector network analyzer, and then the prototype MIMO with DGS antenna was fabricated.