Design and Simulation of Flexible Wearable Dual-Band Filter with Felt Substrate for Use in Medical Systems

In this paper, a wearable dual-band filter is designed and simulated to operate on ISM frequency bands. For this reason, in addition to recognizing the mentioned frequency bands, the design process of wearable filters has also been studied. In this regard, first, the desired characteristics of a filter are examined. These characteristics include scattering parameters (S-Parameters) and group delay. In the following and in explaining the objectives, by defining numerical values for these characteristics, the framework of the paper is determined. Since the subject of this article is the design of wearable filters, a substrate that has this capability should be used. In this regard, a flexible substrate with felt, thickness 1.4 mm, dielectric constant of 1.45, and tan (δ) = 0.001 has been used. Using this dielectric, a proposed dual-band filter with dimensions of 29.4×33.4 mm2 was designed. The frequency bands covered include 2.4-2.5 GHz and 5.15-5.35 GHz. These bands are standard values covered by ISM. At all operating frequencies, the conditions S11 < -10 dB and S21 > + 0.5 dB are met.