Meander Microwave Bandpass Filter on a Flexible Textile Substrate

Abstract

This paper presents an alternative process to fabricate flexible bandpass filters by using an embroidered yarn conductor on an electronic textile. The novelty of the proposed miniaturized filter is its complete integration on the outfit, with benefits in terms of compressibility, stretchability, and high geometrical accuracy opening the way to develop textile filters for wearable applications in sport and medicine. The proposed design consists of a fully embroidered microstrip topology with a length equal to quarter wavelength (λ/4) to develop a bandpass filter frequency response. A drastic reduction in the size of the filter was achieved by taking advantage of a simplified architecture based on meandered-line stepped impedance resonator. The e-textile microstrip filter was designed, simulated, fabricated, and measured with experimental validation at a 7.58 GHz frequency. The insertion loss obtained by simulation of the filter was substantially small. The return loss was greater than 20 dB for bands. To explore the relations between the physical parameters and filter performance characteristics, a theoretical equivalent circuit model of the filter constituent components was studied. The bending effect of the e-textile filter was also studied. The results showed that by raising the radius of bending to 40 mm, the resonance frequency was raised to 4.25 MHz/mm.

A Very Compact Quintuple Band Bandpass Filter Using Multimode Stub Loaded Resonator

“…The shifting of frequencies has been raised due to magnetic coupling between the resonators. Similarly, the equations for f even,2 and f odd,2 based on the design proposed in Figure 2 are calculated and given in Equations (25) & (26), respectively.…”

“…Based on Equations (25) & (26), the corresponding f even,2 = 1.92 GHz and f odd,2 = 2.08 GHz. Similarly, the rest of the passbands are predicted based on the physical dimensions of the stubs loaded in the proposed design and implementing Equations (11)-(22) on the designed filter.…”

“…Maximum transmission zeros are achieved in [25] by analyzing the loaded and unloaded Q-factor in triple bandpass filter. Also, a meander bandpass filter is designed in [26] to operate at 7.65 GHz.…”

E-Textile Metamaterials: Stop Band Pass Filter

“…On the other hand, metamaterials (MTMs) [3,4] are an attractive topic for researchers recently, which they have applied for improving microwave systems such as antennas, filters, and sensors [5][6][7]. Recently, MTMs have been integrated into textiles and have led to the development of MTM in a variety of reported fields, such as e-textile metamaterial transmission lines [8], MTM textile sensors [9], MTM microwave absorbers [10], double ring resonators garment antenna [11], and (in the field of filtering) e-textile band pass filters [12]. Furthermore, split-ring resonators (SRRs), which were introduced by [3,13], make an effective magnetic coupling with microstrip topology, that they don't need additional magnetic materials.…”

Wideband Band-Pass Filter Design Using Coupled Line Cross-Shaped Resonator

“…Based on U-shape DGSs, an ultra-wide stopband is achieved. In [10][11][12][13][14][15][16][17], the cross-shaped resonator and the coupled line have been proposed and studied. Open-circuit lines, short-circuit lines, and others are used to construct a good performance bandpass filter, which provides ideas for the design of this filter.…”