The objective of this research is to develop an equivalent circuit model for a compact multiband antenna capable of operating at six frequency bands. The antenna that is being demonstrated is built on an FR4 substrate (1.6 mm thick) which consists of a ground plane on the rear side. It is easily integrated into a variety of RF front-end systems due to its compact size (24 mm \(\times \) 19 mm \(\times \) 1.6 mm). The antenna that has been evaluated operates in the C as well as L bands across 6 distinct frequency ranges: 2.54, 2.65, 3.53, 4.35, 5.28, and 5.68 GHz, which supports 5G as well as IoT services. Under reviewed antenna demonstrates frequency (very low) ratios among 2 consecutive bands, with values of 1.04/1.3/1.23/1.22/1.08, respectively. The hexa-band antenna was modeled in ADS with an equivalent circuit. The accuracy of this model was evaluated by comparing its simulated reflection coefficient to that derived from HFSS simulations, which demonstrated a strong correlation.