Using USB connector to generate 5th-resonant mode in loop antenna

Metallic components such as USB connectors used in mobile phones can easily affect the performances of antennas placed nearby. This paper illustrates the use of the metallic USB connector in a very compact loop antenna with a volume of 5×8×60 mm³ to generate an additional resonant mode at about 3.13 GHz. A standard metallic USB connector is placed inside the loop radiator of the antenna to generate a 5th-resonant mode (the 2.5-λ resonant mode). Studies show that the USB connector has little effects on the other four resonant modes. Moreover, the 5th-resonant mode generated can also been independently tuned using its location. The proposed antenna is studied using computer simulation. The final design is also fabricated and measured using the Satimo Starlab system. Measured results agree well with simulated results.