This paper presents an effective approach to a compact antenna system incorporating a single artificial magnetic conductor (AMC), designed to operate in the GSM and WiFi frequency bands. The proposed system features a dual-band AMC single element measuring 60 × 60 mm2 with
$\pm90^{\circ}$ bandwidths of 100 and 170 MHz. A comprehensive parametric study was conducted to optimize performance and determine the AMC phase while maintaining the compact size of the antenna system. Significant improvements in gain were observed, from −1.61 to 1.88 dBi at 0.9 GHz and from 3.33 to 5.66 dBi at 2.45 GHz. Additionally, the complete system achieves a compact electrical size of 0.18λ0 × 0.18λ0 × 0.048λ0, with an increased front-to-back ratio of 12.3 and 19.9 dB at both frequencies. Finally, measurements of the fabricated prototype show good agreement with the simulation results.