In this paper, a simple and efficient method to increase the gain and bandwidth of the wearable antennas used in several medical/communications systems is presented. To increase the gain and bandwidth simultaneously, the triple transmission lines (TTLs) method has been used. With this method, the frequency ranges of 1.7–2.5 and 5.4–5.95 GHz are covered with dual-band responses. Also, the simulated maximum gain at 2 and 5.8 GHz is equal to 8.26 and 9.86 dB, respectively. Using the TTLs method, the second frequency band (5.4–5.95 GHz) is achieved. Also, the gain improvement in operating frequencies is more than 4 dB compared to the conventional antenna. The dimensions of the proposed wearable high-gain antenna are 80 × 92 × 2 mm3 or 0.57 × 0.67 × 0.01 λg3 at 2 GHz. Finally, a dual-band sample antenna for use in medical systems was fabricated with a flexible felt substrate and its characteristics were measured. There is a good fit between the measurement and simulation results.
