Dual frequency microstrip patch antenna for WLAN/Bluetooth and HIPERLAN applications

The subject of this paper is a dual frequency microstrip patch antenna operating at 2.45 GHz and 5.2 GHz ISM (industrial, scientific and medical) band. The IEEE 802.11b WLAN (wireless local area network) and Bluetooth standards utilise the 2.45 GHz band and 5.2 GHz is specified as an operating frequency in HIPERLAN (High PErformance Radio Local Area Network) standard. Antenna design was based on the previously developed dual frequency microstrip patch antenna. Adjustment for the desired frequencies, 2.45 GHz and 5.2 GHz, was achieved by using two different multiplying factors and setting the gaps between the two patches so that the return loss would be under 40 dB. Although the antenna was fabricated of a high-loss FR4 substrate material, it performed well having a matching of 32 dB for the lower and 13 dB for the upper resonant frequency. The bandwidth was over 100 MHz for both of these frequencies. FR4 was chosen as a substrate material for cost savings.