1 Introduction

Lately, wearable textile antennas have attracted a growing interest from researchers in academia and industry due to their wide range of applications in wireless body area network (WBAN) including areas such as sports, healthcare, security, intelligent garments, and military systems. (Hassan and Shehab 2015). The development of wearable antennas made of smart textiles, especially woven fabrics, is attractive for vital signs and detection systems because they provide significant benefits such as low production complexity, low cost, high flexibility, light weight, and easy integration into the garment (Shakhirul and Jusoh 2014). Wearable textiles are good choices for use as substrates due to their low-permittivity, for increasing the impedance bandwidth of the antenna (Salvado and Loss 2012; Mersani and Lotfi 2018). Among different fabrics, felt (Mohandoss and Palaniswamy 2019; Hong and Tak 2016) and denim (Gao and Yang 2018; Yalduz et al. 2019; Ashyap and Zainal 2019; Abdu and Zheng 2018) are broadly used kinds. For wearable applications, substrates that are flexible, include paper, polymer, Ninja Flex, PDMS, and Kapton have been suggested in the literature (Alqadami and Bialkowski 2019; Rizwan and Khan 2017; Hamouda and Wojkiewicz 2018). Conformal antennas are highly recommended in order to maintain mechanical agility while retaining the original shape and features of the antenna (Huang and Zhou 2021). The denim is commonly utilized for textile applications (Sundarsingh 2014).

Numerous geometries of the wearable textiles antennas have been constructed. The author of Arif and Zubair (2019) developed a fractal antenna for use at 2.4 GHz. An impedance mismatch in the operating frequency is caused due to the human body loading resulting in only 7.75% fractional bandwidth. The antenna is also not suitable for integration into a compact portable receiver. Ref. (Mohan and Florence 2019) presents a compact triangular patch antenna, but its operating bandwidth is significantly narrow. Another research (Agneessens and Lemey 2015a) describes a wearable antenna for medical applications using fabric as the substrate and knitted Copper as a patch and ground plane. The overall sizes of the antenna are too large for compact environments. A transparent flexible ultra-wideband (UWB) antenna was for imaging human breasts (Saeidi and Nozad 2020). The antenna is made of three layers of Kapton polyimide substrate with 3.5 dielectric constant. A transmission line connecting to three regularly spaced spiral patches provided abroad bandwidth ranging from 3.26 to 23.37 GHz.

On the other hand, (Mersani and Osman 2019), uses a compact antenna with an artificial magnetic conductor (AMC) for skin cancer detection. In (Saeidi and Ismail 2020), the construction of a monopole antenna for breast cancer detection uses flexible textile materials, with felt as the substrate. A wearable antenna is constructed using denim as a substrate and a conductive material for shielding (Jebali and Gharsallah 2020). The antenna contains eighteen met material unit cells and operates in the frequency spectrum of 5.2–22.2 GHz, with 5.85 dBi maximum gain and 78% radiation efficiency. However, these antennas suffer from either a narrow BW or a low gain.

When designing wearable devices with integrated antennas, it is crucial to take into account the potential radiation emitted when these antennas are in close proximity to the human body. To avoid radiation damage to human tissue, the radiation dose should be as low as possible. The level of radiation can be determined using SAR analysis. In (Govindan and Palaniswamy 2021) describes the progress of a wearable quad-port MIMO antenna utilizing commercially available, inexpensive silicone wristbands. Typically, these antennas are developed to be worn on the body. Despite this, the antenna performance metrics, such as efficiency and gain, are degraded when the antenna is closest to the body. Additionally, when an antenna is attached to human body, the electromagnetic–waves (EM) emitted by the antenna permeate deeper into the body, as a result of the system SAR increase.

Compact textile antennas with a straightforward design are required by modern communication system architecture. The design of an antenna with such features is constantly a challenge problem. There have been many striving to minimize the size of the textile antenna, including: quarter-wave designs (Agneessens and Lemey 2015b) and shorting pins (Wong and Virtually shorted patch antenna for circular polarization. IEEE Antennas Wireless Propag. 2010). However, such techniques always degrade either the radiation performance or the impedance matching. Another challenge with the compact wearable antennas is waves absorbed by human tissue (Islam and Azam 2022; Samsuzzaman and Islam 2019; Prudhvi and Madhav 2020; Shazzadul and Kayser 2022; Kapetanakis et al. 2021).

In this study, we present a solution to address the aforementioned challenges by proposing a compact full-textile two elements UWB-MIMO antenna with orthogonal polarization for nearfield biomedical diagnostic applications such as breast cancer detection. The antenna is constructed using a cotton substrate and a copper-polyester conductor fabric, to further increase the impedance bandwidth (BW) with a partly grounded. A low-pass filter with extremely substantial out-of-band rejection is recognized to mitigate coupling of the constituents. The textile substrate used in the antenna is low cost, resulting in a low cost antenna design. Furthermore, the proposed antenna exhibits a stable temporal response and remains sustainable even after multiple washing cycles. Utilizing commercially accessible simulation software CST STUDIO SUITE ver. 2021, the performance of the antenna is assessed, it achieves a maximum gain of 6 dBi and a bandwidth extends from 2.5 GHz to 12 GHz.

2 Design geometry

The geometry of the prospective textile UWB flexible MIMO antenna with orthogonal polarization is depicted in Fig. 1. The feeding structure is suggested to be CPW-fed for fabrication and integration simplicity. The proposed wearable design mainly consists of a radiating corrugated half circle, feeding network and a partly grounded. Impedance-matching enhancement is achieved utilizes the partial ground plane. The CPW feeding structure signal line is tapered with \({{\text{W}}}_{{\text{t}}}=2.5\mathrm{ mm}\) for further impedance bandwidth improvement over the entire band. To mitigate the reciprocal coupling between the antenna radiating constituents, a strip line is incorporated to act as a LPF with a vast range of out-of-band rejection. This LPF consists of a conducting fabric material is positioned between the two monopole antennas. By aligning the stop band characteristics of the LPF with the operational frequency of the antenna, the induced signal is almost prevented from passing between the two elements, effectively reducing the mutual coupling. The prospective antenna is simulated and fabricated on a textile substrate with dielectric permittivity \({\upvarepsilon }_{\mathrm{ r}}\) = 1.8, a loss tangent of 0.025, and thickness \(h = 0.3 mm\). The suggested MIMO antenna has dimensions \(\mathrm{L }= 60\) mm and \(\mathrm{W }= 70\mathrm{ mm}\). The simulated operating bandwidth ranges from 3.5 GHz to 11.65 GHz as depicted in Fig. 2. The ultimate values of the suggested textile antenna design parameters are illustrated in Table 1.

Fig.1
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Geometric design of the proposed antenna

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Fig. 2
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Simulated S-parameters for the proposed textile antenna

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Table 1 Dimensional specifications of Cpw-Fed monopole antennas (mm)
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3 Antenna design

Numerous simulations have been carried out as a preliminary investigation to monitor how each alteration affects the antenna performance. Figure 3 shows the design procedure, which consists of five steps. According to Fig. 1, the suggested antenna is symmetrical with regard to its axis. The prospective wearable design emerged as a simple circular patch monopole antenna with CPW feed as illustrated in Fig. 3a, which evolves into a half disc monopole antenna as depicted in Fig. 3b. Equation (1) was used to select the radius of the radiating element.

$$a = \frac{{\text{f}}}{{\left( {1 + \frac{{2{\text{h}}}}{{\uppi \upvarepsilon_{r} {\text{f}}}}\left\{ {\ln \left( {\frac{{\uppi {\text{f}}}}{{2{\text{h}}}}} \right) + 1.7726} \right\}} \right){\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{$2$}}}}$$
(1)

where, f is the lower edge frequency of the antenna operating bandwidth. The operational bandwidth is then improved by modifying and blending the partially grounded, as depicted in Fig. 3c. To miniaturize the antenna, we increased the current path by increasing the radiating element length by cutting out a group of small circles from its boarders as shown in Fig. 3d. Finally, a tapering technique is used in the feeding structure to further impedance-matching improvement as illustrated in Fig. 3e. Comparisons for the reflection coefficient (\({S}_{11}\)) for the five antennas are illustrated in Fig. 4.

Fig. 3
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Design procedures. a Step-1. b Step-2. c Step-3. d Step-4. e The proposed structure

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Fig.4
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Reflection coefficient of the five development stages of the antennas

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3.1 MIMO mutual coupling reduction

Generally, mutual coupling occurs when the electric or magnetic fields transfer from one antenna to the other which is in close proximity. This can lead to degradation of antenna radiation patterns, impedance matching, and overall system performance. The proposed MIMO structure consists of two antenna parts are positioned orthogonally; the vertical element is rotated \({90}^{o}\) clockwise from the adjacent part as indicated in Fig. 1. This organization is partly responsible for the improvement of the level of isolation for the achievement of good performance.

Figure 5 indicates MIMO surface current distribution construction without any decoupling configuration, when port (1) is excited and the port (2) is terminated. It can be seen that there is a certain amount of current at port (2), means that the coupling must be further minimized. For this reason, a simple decoupling construction is proposed to promote isolation between elements of the antenna. The concept of the decoupling configuration is based on the design of an LPF with out-of-band rejection that (Elsharkawy et al. 2022). A strip line is a type of transmission line that consists of a conductive strip embedded between two parallel conductive plates; the ground plane. This configuration allows it to be used as a low pass filter (LPF) by exploiting the principles of transmission line theory.

Fig. 5
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Surface current distribution for the MIMO elements without the decoupling structure when port 1 is excited a 3.7 GHz and b 5 GHz

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When an input signal is applied to the antenna port, it travels along the conductor between the ground plates. A strip line works as a LPF with vast out-of-band rejection. Figure 6 shows the electric current distribution after adding the decoupling struture. It is clear that the coupling is reduced between MIMO elements. The LPF cut off frequency is below the lower edge of the antenna operating frequency. Accordingly, at LPF stop band, the strip line exhibits significant attenuation. The cutoff frequency of a strip line LPF is determined by the physical dimensions of the strip line, such as the width and separation of the strip and the ground plates. Low pass filter characteristics can be further tuned by modifying the physical parameters. For example, changing the width and separation of the strip and the ground plates can shift the cutoff frequency and hence affect the mutual coupling.

Fig. 6
figure 6

When port 1 is excited at a 3.7 GHz or b 5 GHz, the surface current distribution for the suggested MIMO elements with the decoupling structure

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3.2 Parametric analysis

In this section, to provide better justifications for how we selected each dimension of the proposed textile MIMO antenna, numerous parametric analysis are investigated. By presenting the effect of each parameter on the antenna performance, the effectiveness of each part of the antenna and its capabilities will be more visible. In the First parametric in Fig. 7, the decoupling structure is studied for different values of its width. It is observed that with increasing the \({W}_{strip}\) value, the amount of isolation between the patches enhanced due to improving the out-of-band rejection of the LPF.

Fig.7
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The decoupling structure width effect on S21 versus frequency

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The effect of increasing the current path by varying the radius of the subtracted circles, \(rs\) from the radiating elements is illustrated in Fig. 8. The influence of changing the radius of the half circle radiator \(a\) is presented in Fig. 9. Figure 10, examines changes in parameter \({W}_{t}\) from 2.5mm to 4.5mm. It can be noticed that \({W}_{t}\) is mainly responsible for the impedance- matching between the structure and the feeding line. The obtimum value of the \({W}_{t}\) is 2.5 mm.

Fig.8
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The effect of changing radius of circle subtracted from the main patch perimeter

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Fig.9
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The influence of changing the radius of the main radiator \(a\)

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Fig. 10
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The effect of tapering width on the impedance matching

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3.3 MIMO performance assessment

To confirm that the chosen MIMO antenna is appropriate for a range of biomedical applications, it is imperative to evaluate the envelope correlation coefficient (ECC), diversity gain, Antenna Mean Effective Gain (MEG), and minimal total average reflection coefficient (TARC). A reduction in the correlation factor denotes greater diversity. These metrics are used to assess the effect on signal transmission capacity as it travels via various radio frequency signal propagation channels. For MIMO to function at its best, an ECC of less than 0.1 is required; better performance is associated with reduced correlation. In the far field, the ECC (ρe) of a MIMO antenna is written as (El-Nady and Abd El-Hameed 2023).

$${\rho }_{e}=\frac{{\left|\iint \left[\overrightarrow{{E}_{1}} \left(\theta ,\varphi \right)\overrightarrow{{E}_{2}} \left(\theta ,\varphi \right)\right]d\Omega \right|}^{2}}{\iint {\left|\overrightarrow{{E}_{1}} \left(\theta ,\varphi \right)\right|}^{2}d\Omega \iint {\left|\overrightarrow{{E}_{2}} \left(\theta ,\varphi \right)\right|}^{2}d\Omega }$$
(2)

Here, ϕ, θ, and Ω stand for azimuth, elevation, and solid angles, respectively. When the excitation is given from either port 1 or port 2, the radiation pattern in the far field is represented by the variables azimuth, elevation, and solid angles and \({E}_{2}\). Using the S-parameters of the antenna elements, the ECC can be computed using the equation that follows:

$$ECC=\frac{{\left|{s}_{11}^{*}{s}_{12}+{s}_{21}^{*}{s}_{22}\right|}^{2}}{\left(1-{\left|{s}_{11}\right|}^{2}+{\left|{s}_{21}\right|}^{2}\right)\left(1-{\left|{s}_{22}\right|}^{2}+{\left|{s}_{12}\right|}^{2}\right)}$$
(3)

Although this method is simple, compared to a far-field calculation, its simplicity comes at the expense of accuracy. The ECC curves derived from the modeled far-field radiation patterns of the suggested MIMO antenna are shown in Fig. 11. It is significant to note that the ECC's peaks are continuously less than 0.1. These results highlight the recommended design's excellent ECC performance.

Fig. 11
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The ECC of the proposed MIMO antenna

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One important component of MIMO antennas is the DG. Roughly 10 dB of DG value is required for the MIMO system. In terms of ECC, the DG is expressed as (Sarfraz 2023; Al-Ani and Abd-Alhameed 2020):

$$DG=10\sqrt{1-{ECC}^{2}}$$
(4)

The good diversity performance of the planned antenna can be ensured by adjusting the DG within the required range of 0.999 to 10, as seen in Fig. 12.

Fig. 12
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The simulated and measured DG of the proposed MIMO antenna versus frequency

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The ratio of the total reflected power to the total incident power is squared to obtain the minimal TARC, a statistic used in MIMO antenna systems as expressed in Eq. (5).

$${\Gamma }_{a}^{t}=\frac{\sqrt{\sum_{i=1}^{N}{\left|{b}_{r}\right|}^{2}}}{\sqrt{\sum_{i=1}^{N}{\left|{a}_{i}\right|}^{2}}}$$
(5)

The incident and reflected signals are denoted by the parameters \({a}_{i}\) and \({b}_{r}\), respectively. The TARC curves are shown in Fig. 13. Phase angles diverge when feeding port #1 with source \(1{e}^{j0}\), even though the other ports show equivalent magnitudes. The operational bandwidth of the proposed antenna is essentially unaffected by the modest change in feeding phases of the remaining ports.

Fig. 13
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The TARC of the anticipated MIMO antenna

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The MEG, defined as the ratio of the average power received at the microwave circuit to the total average power of the vertically and horizontally polarized waves received by an isotropic antenna, is presented in Fig. 14. The MEG, depicted as less than -3 dB, can be calculated using the following equation:

$${\text{MEG }} = { }0.5\left[ {1 - \mathop \sum \limits_{j = 1}^{N} \left| {Sij} \right|} \right]$$
(6)
Fig.14
figure 14

The antenna mean effective gain versus frequency

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where N is the number of antenna elements.

4 Time domain analysis

Time domain analysis presents the system response to various inputs over time and demonstrates its transient and steady-state behavior. In time domain analysis, the input to the system is typically represented as a time-varying function or signal (Abd and Wahab 2019). The output of the system is then analyzed to determine its characteristics, such as its amplitude, frequency, and phase. A setup, depicted in Fig. 15, is evaluated to study the proposed antenna time domain performance. The structure includes a receiver / transmitter antennas. The transmitting antenna rotates in a circular perimeter with azimuth angle of (\({0}^{0}\),\({45}^{0}\),\({90}^{0}\)), while remaining the receiving antenna in a fixed position. To extend the UWB range under investigation, a first-order Gaussian pulse input signal is used for the transmitting antenna. This section looks into two distinct cases. The first case, when both the transmitting and receiving antenna have same polarization. The opposite situation is when the the transmitting and the receiving antennas have perpendicular polarization. As presented in Fig. 16, the received signal in both cases demonstrates good time domain effectiveness at various angular positions with little pulse decay, making it advantageous to be incorporated into numerous UWB nearfield biomedical diagnostic applications such as breast cancer detection.

Fig. 15
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Time domain analysis setup

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Fig. 16
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Time domain analysis. a The transmitting and receiving antennas are horizontally polarized. b While the receiving antenna is vertically polarized, the transmitting antenna is horizontally polarized

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5 Experimental results

The proposed design is fabricated on a textile substrate with conductive copper nanoparticles using a laser cutting machine. The employed conductive copper nanoparticles has surface resistivity of 0.05 Ohm/Square. The DAK 3.5 (200 MHz—20 GHz) device at the ERI laboratory in Egypt was utilized to measure the dielectric constant and loss tangent of the cotton substrate, ensuring high measurement repeatability (typically within ± 1% accuracy). The measurement setup is illustrated in Fig. 17a, while Fig. 17b display the measured dielectric constant and loss tangent. The measured relative permittivity is approximately 1.8, with a corresponding loss tangent of around 0.05 across a significant portion of the frequency spectrum. The wearable textile antenna prototype is depicted in Fig. 18a. The conductive fabric, which includes an adhesive layer, can be ironed directly onto the dielectric fabric that is intended for incorporation. In addition, the textile-based MIMO wearable antenna completely avoids heat when connecting the SMA connector. Instead, conductive adhesive, also known as epoxy glue, is used to attach the suggested antenna for measurement. Figures 18b, c compare reflection coefficient data from simulation and experiment. Good impedance matching were achieved with the simulated and fabric textile antenna. The suggested textile antenna covers the whole simulated 3.5–11.65 GHz UWB spectrum with a reported -10 dB impedance bandwidth from 2.5 to 12 GHz. On the other hand, there are some slight inconsistencies due to factors not considered in the simulations, as the SMA connectors, manufacturing tolerances and soldering errors. The radiation patterns are measured using anchoic chamber at the ERI laboratory in Egypt as shown in Fig. 19a. The simulated and measured polar radiation patterns are provided for the y–z and x–y sectors at frequencies of 4.7 GHz, 6 GHz, and 10 GHz, respectively, as shown in Fig. 19b, c, d, e, f, g. The radiation is almost omnidirectional. Observing a divergence between the measured and simulated results reveals some discrepancies. These variations can be attributed to factors such as fabrication tolerances, the omission of solder paste in the simulation phase, and the impact of connectors. As illustrated in Fig. 20, the suggested MIMO wearable antenna achieves a measured gain of 6 dBi, and efficiency about 96%.

Fig.17
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Dielectric constant measurement of the cotton substrate. a Measurement setup. b Reltaive permittivity versus frequency

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Fig.18
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Fabricated prototype on conductive fabric and scattering parameters measurements. a Measurement setup. b Reflection Coefficient. c Transmission coefficient

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Fig.19
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Simulated and measured radiation patterns of the proposed wearable MIMO antenna a Measurement setup. b y–z cut at 4.7 GHz, c x–y cut at 4.7 GHz, d y–z cut at 6 GHz, e x–y cut at 6 GHz, f y–z cut at 10 GHz, () x–y cut at 10 GHz

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Fig.20
figure 20

Gain and efficiency of proposed MIMO wearable antenna. a Simulated and measured gain vesus frequenct. b Simulated efficiency

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The benefits of the suggested wearable antenna over the existing wearable antennas are illustrated in a comparison table (Table 2). The proposed antenna size, bandwidth, and gain are compared to related work that is already published in the literature. As opposed to other antennas, our suggested one has the lowest profile that provide lower SAR and greater fractional bandwidth and gain, making it suitable candidate for wearable technology.

Table 2 Performance evaluation in compared to other wearable antennas
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6 Specific absorption rate evaluation

To ensure safety, it is important for the patient to avoid any potential health risks. SAR is measured to assess the wearable antenna safety by measuring the quantity of this radiation that human tissue absorb. The tools used for this measurement composed of the left and right side of the SAM head phantom as well as a flat phantom for measurements worn on the body that satisfies the requirements of the IEC and FCC for tissue imitating medium. According to IEC62209-1, IEEE1528, FCC OET65, and other standards, Speag Switzerland is used to do incredibly accurate SAR measurements (cSAR3D) from equipment worn on the body. Measurements made by cSAR3D are quick 0.3 s and reproducible 0.1 dB extend from 0.65 to 6 GHz (Rydholm and Fhager 2018). The entire SAR measurement setup for the wearable antenna is illustrated in Fig. 21. The antenna is assessed at the central laboratories of the Electronics Research Institute using instruments for the measurements of SAR at various power settings. If the maximum SAR emission of the antenna does not exceed 1.6 W/kg, it can be regarded as safe (Rydholm and Fhager 2018; Romeo and Donato 2011; Shah and Basir 2023; Shah and Zada 2023). Table 3 display the measured SAR values at 4 GHz and 6 GHz for the suggested antenna textile.

Fig.21
figure 21

SAR measurements of the proposed conductive textile antenna. a SAR at 4 GHz and 5 dBm. b SAR at 6 GHz and 5 dBm. c SAR at 4 GHz and 10 dBm. d SAR at 6 GHz and 10 dBm. e SAR at 4 GHz and 15 dBm. f SAR at of 6 GHz of 15 dBm. g Measurement setup

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Table 3 Comparing measured SAR values for the suggested wearable MIMO antenna
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7 Bending and wash ability effects

7.1 Bending effect

Due to the planned positioning of the antenna around specific body parts, there will be limitations related to curvature. To assess how these curvatures affect the performance of the proposed antenna, we have designed the antenna in a cylindrical and spherical form to investigate its capability to maintain the desired operating bandwidth. Figure 22a and b depict the scenarios of the antenna bent in a cylindrical shape and the corresponding outcomes. Different cylinder radii are considered for this test; 50 mm, 70 mm and 90 mm. The simulated S-parameters are depicted as a function of curvature in Fig. 22c and d. The antenna exhibits a bandwidth between 3.5 and 11.65 GHz in the flat case. Within the frequency range of 2.4 GHz to 4.5 GHz, a minor mismatch is seen when a simulated cylinder is bent with a radius of 50 mm. On the other hand, in measurement results, the effect of bending has lower effect on both reflection coefficients and transmission coefficients as depicted in Fig. 22e and f. The robustness of the proposed textile antenna to the effects of bending is demonstrated by the relatively slight bandwidth fluctuations before and after bending.

Fig. 22
figure 22

The results of various bending radii with cylinder modes in terms of S-Parameters, both measured and simulated. a Simulation Setup. b Measurement Setup. c Simulated \({{\text{S}}}_{11}\). d Simulation \({{\text{S}}}_{21}\). e Measured \({{\text{S}}}_{11}\). f Measured \({{\text{S}}}_{21}\)

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The spherical bending instance and the accompanying outcomes are shown in Fig. 23a and b. For this test, three different spherical radii 75 mm, 100 mm, and 125 mm are considered. The simulated Scattering-parameters are depicted as a function of curvature in Figs. 23c and d. The antenna bandwidth in the flat casing ranges from 3.5 to 11.65 GHz. A small mismatch is depicts the simulated spherical curvature when bent with a radius of 75 mm in the spectrum of frequency extends to 4.8 GHz and 5.7 GHz. The reflection coefficient for spherical bending is < 8.7 dB in these frequency ranges. However, the measurement outcomes demonstrate that the effect of bending has less influence on both the reflection coefficient and the transmission coefficient, as illustrated in Fig. 23e and f.

Fig. 23
figure 23

Results of S-Parameter measurements and simulations for various bending radii with sphere modes. a Simulation Setup. b Measurement Setup. c Simulated \({{\text{S}}}_{11}\). d Simulated \({{\text{S}}}_{21}\). e Measured \({{\text{S}}}_{11}\). f Measured \({{\text{S}}}_{21}\)

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7.2 Washing tests

The four washing factors, often referred to as the Sinner factors, encompass parameters like time, temperature, mechanical agitation, and the chemistry or biology involved. These factors are applied to items subject to washing in every laundering process (Wagner 2017; Ellmer and Wäsche-Cluster in Konsumentenhaushalten 2016; Rotzler and Kallmayer 2020). The favorable results pertaining to hygiene and cleanliness, as well as the undesirable, secondary effects of washing, such as physical damage, aging, alterations in shape, or color shifts, are contingent upon the extent to which these interconnected elements are implemented. A textile may indicate any or all of the subsequent secondary wash effects as a result of the influence of the four elements combined with the wash water. After 1, 2 and 3 cycles of machine washing with powder or liquid detergent using the following settings:, \({40{\text{C}}}^{o},\) speed 400 rpm and 30 min for each cycle the performance of the suggested antenna was then examined. The prototype was tumble dried but not ironed after each wash cycle. It is important to note that the antenna is safeguarded within a textile cover to prevent the connectors from being misplaced. Figure 24 illustrates the outcomes of the prototype, demonstrating that the proposed textile antenna maintains its effective functionality.

Fig. 24
figure 24

The measured reflection coefficient results of different cycles wash ability. a Antenna wash ability. b Measured \({{\text{S}}}_{11}\). c Measured \({{\text{S}}}_{21}\)

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8 Conclusion

A two port dual-polarized flexible UWB MIMO wearable antenna design with a compact size is fully analyzed for use in nearfield biomedical diagnostic applications. It comprises a broad band from 2.5 GHz to 12 GHz. The antennas employ polarization diversity to reduce the required array size while preserving high image accuracy, which makes them suitable for wearable breast imaging applications. There is a consensus between the results obtained from simulation and measurement. The textile suggested antenna has maximum gain of 6 dBi, and a 96% efficiency. In order to ensure flexibility, a range of bending conditions were analyzed, and the durability of the textile antenna prototype was assessed through wash ability testing. Safety was confirmed by measuring SAR. Furthermore, time domain analysis and MIMO performance were lead to investigate the antenna's suitability for use in an imaging system.