Inverted LFL Antenna for Dual‐Band Operation

A dual‐band antenna called the inverted LFL antenna (InvLFL) is made of a thin conducting film, where both the top radiation element and the ground plane lie in the same plane, that is, the InvLFL has a card antenna structure. The card structure differs from the layered antenna structure for dual‐frequency operation, where the ground plane backs a radiation element. It is emphasized that the InvLFL is intended for installation in mobile equipment. In such a case, polarization purity is not required; however, an appropriate frequency response for the voltage standing wave ratio (VSWR) is important. This chapter presents the steps involved in reaching the InvLFL configuration. The analysis for the design is performed using the finite‐difference time‐domain method (FDTDM) based on Yee's algorithm and the antenna excitation is modeled by a delta‐gap voltage source V
_in
(t), which is defined by a sine function modulated by a Gaussian function.