A Compact Tri-Band Antenna Based on Inverted-L Stubs for Smart Devices

We designed and constructed a novel, compact tri-band monopole antenna for intelligent devices. Multiband behavior was achieved by placing inverted-L shaped stubs of various lengths in triangular fed coplanar waveguide. The resonance frequency each band can be controlled varying the length corresponding stub. Three bands, at 2.4 (2.37–2.51), 3.5 (3.34–3.71), 5.5 (4.6–6.4) GHz, were easily obtained using three different lengths. For miniaturization, portion longest stub (at GHz) printed on opposite side substrate, connected to main via shorting pin. To validate concept, fabricated low-cost 1.6-mm-thick FR-4 substrate with dimensions 20 × 15 1.6 mm3. exhibited moderate average gain 2.9 dBi an omnidirectional radiations over bandwidths required RFID, Bluetooth, ISM, WiMAX, WLAN-band applications. These features make suitable smart