Frequency-Tunable Antenna Using IFA-to-Loop Mode Switching for Compact Wireless Devices

This paper introduces a new approach to reconfiguring an antenna’s operating frequencies by switching between an inverted-F antenna (IFA) mode and a loop mode. This frequency agility is achieved by incorporating a switch at the end of the antenna trace, which connects or disconnects the trace from the antenna ground, thereby altering the antenna's resonant behavior depending on the selected mode. To validate the concept, a prototype antenna was fabricated, and the measured results showed strong alignment with simulation predictions. In the IFA mode, the antenna exhibits two resonant frequencies around 1 GHz and 2 GHz, while in the loop mode, it achieves two close resonances approximately at 1.4 GHz and 1.7 GHz. This ability to switch between modes and cover multiple frequency bands makes the proposed design particularly well-suited for LTE-enabled mobile devices that demand wide or multi-band operation.