You can go through the following two papers for simple RLC circuit representation of metamaterial absorber:

1. Somak Bhattacharyya, Saptarshi Ghosh, and Kumar Vaibhav Srivastava, “Equivalent Circuit Modeling of an Ultra-thin Dual-Band Microwave Metamaterial Absorber,” accepted for presentation in IEEE Asia Pacific Microwave Conference (APMC) 2014, 4-7 November, 2014, Sendai, Japan.

2. Somak Bhattacharyya, Saptarshi Ghosh, and Kumar Vaibhav Srivastava, “Equivalent Circuit of an Ultra-thin Polarization-Independent Triple Band Absorber,” AIP Advances, Vol. 4, Issue 9, pp. 097127, 2014.

Thank you @somak   sir

Hi,

You can also figure it out taking a look to the following papers:

1. Fernández Álvarez, H.; de Cos Gómez, M.E.; Las-Heras, F. A Thin C-Band Polarization and Incidence Angle-Insensitive Metamaterial Perfect Absorber. Materials 2015, 8, 1666-1681.

2. Fernández Álvarez, H.; de Cos Gómez, M.E.; Las-Heras, F. A Six-Fold Symmetric Metamaterial Absorber. Materials 2015, 8, 1590-1603.

Best wishes