Design and development of multiband microstrip patch anthenna for tablet PC

Abstract

With the increasing demand of using multiple services in a single device, instead of using multiple antennas, current trend is to use single antenna capable of communicating in multiple frequency bands. For the devices like tablet PC, the need of accommodating the physical infrastructure through single multiband antenna is greatly useful. For the multiband operation, two monopole structures are modified and proposed for tablet PC. Embedded resonant structure and Gamma shaped monopole structure are designed and simulated using the Computer Simulation Technology (CST) Microwave Studio. The modified embedded parallel resonant monopole patch is implemented by removing the inductor chip from the embedded parallel resonant monopole patch. The antenna is resonant at six frequencies of 0.768 GHz, 2.236 GHz, 2.608 GHz, 2.932 GHz, 3.296 GHz and 3.496 GHz. The radiation efficiency varied from 80.12% to 94.46%. The peak gains are also found to be above 2.1dBi with a range varying from 2.6648dBi to 5.9652dBi. The fifth resonant frequency is having the closest matching with the 50 ohms line impedance with the lowest return loss at -44.22dB. The modified Gamma shape monopole is derived from the T shaped monopole and the first three resonant frequencies are found to be well improved than the T shaped one. The typical frequencies at 789.5MHz, 988.1MHz, 2.088GHz and 2.376GHz are having peak gain of 2.94dBi, 2.11 dBi, 5.81 dBi, 4.84 dBi and radiation efficiency of 95.57%, 87.32%, 96.67% and 95.36%, respectively. Compared to the T shaped monopole antenna, the Gamma shaped monopole antenna is performing better for the first three resonant frequencies in terms of return loss. This work has achieved to accommodate the multiple frequency bands of GSM750, LTE2500, WiMax2 and IEEE802.11y with the modified embedded parallel resonant structure and the frequency bands of GSM750, GSM850, GSM900, LTE800, LTE2300, PCS-1900 and UMTS are achieved with the multiband antenna using the Gamma shaped monopole structure. Proposed antenna sizes are 60mm x 12mm and 40mm x 15mm that are suitable to fit inside the commercially available tablet PCs. Both the embedded parallel resonant monopole and the Gamma shaped monopole are fabricated using FR4 copper clad board and tested using the Programmable Network Analyzer in the Microwave Lab. The fabricated and the simulated results are in agreement with slight variations due to the line impedance mismatch and other material properties varying from the simulation environment.