This paper represents the design of an on-body patch antenna for biotelemetry made of multi-wall carbon nanotubes. The primary goal of this research is to use a new antenna and monitor changes in the S1,1 parameter to diagnose lung tumors. The substrate of the antenna is composed of FR-4, the ground is made of copper and the patch is built of MWCNT. The antenna is 1.08 mm thick overall, with the patch being 0.010 mm thick, the substrate being 1.06 mm thick, and the ground being 0.010 mm thick. The overall dimension of this antenna is 60 mm by 60 mm by 1.08 mm (3888 mm3). The antenna's performance was evaluated utilizing the lung tumor phantom model's two sizes and placements. The suggested antenna's resonance frequency was determined to be 7.529 GHz. Furthermore, in unoccupied space, we observed a VSWR of 1.2 and -20.75 dB S1,1. S₁₁ is -23.42 dB at 7.452 GHz in the normal lung and -20.77 dB in the tumor-affected lung. This antenna operates at frequencies ranging from 3 to 10 GHz. The proposed antenna has a SAR of 1.425 W/kg in 10 g of tissue.