Co-designing a compact antenna with a variable matching network using varactors

In this paper, we present a compact antenna based on a spiral-shaped printed monopole integrated with a variable matching network. The designed antenna achieves the small size, while obtaining a high efficiency of 92.1 %, a gain of 2.1dB at 1.6 GHz. The variable circuit is built with varactors in order to sweep the resonance frequency of the antenna over a large frequency range from 0.9 GHz to 1.8 GHz. With the advantage of small size and the ability to operate at different frequencies, this can be a good candidate for any slim and light cell phone.