Triple Band Compact Monopole Antenna for Applications Like Bluetooth, WiMAX and WLAN

In this work, a novel triband antenna is developed for wireless local area network (WLAN), worldwide interoperability for microwave access (WiMAX), and Bluetooth application. The proposed antenna is printed on a low-cost FR-4 substrate and has an overall size of 25 mm x 40 mm x 1.6 mm. Coplanar waveguide (CPW) line with characteristic impedance of 50 ohm is used as feed for the designed antenna. A prototype of this antenna is fabricated and tested to validate the simulation results. The measured result shows that the antenna has the triple-band response with frequency bands that correspond to S-11<-10 dB 2.36 - 3.17, 3.8 - 4.35, and 5.69 - 6.02 GHz. The measured gains of the antenna at resonant frequencies of 2.61, 4.115 and 5.85 GHz are 0.756, 0.925 and 1.589 dBi, respectively. Maximum decrement in measured gain is only 0.671 dB which is attributed to losses from connectors and cables. A novel approach, based on a combination of a cap-shaped ground plane and gap coupling technique in the form of an interdigital capacitor (IDC), is used to achieve the characteristic of triple frequency bands. Finally, the utility of the proposed antenna is checked with a four-element MIMO antenna.