**3.1 Medical UWB radar methodology**

normal tissue and low-reflection coefficient of cancerous tissue, as well as based on varying the ground patch width with respect to the value of SAR caused radiation. It is also noted that the antenna length will have an effect on the bandwidth produced,

In 2018, Wang [31] proposed an electromagnetic imaging for brain stroke detection based on the changes in the electrical impedance of human tissue in frequency 1–4 GHz with the use of scattered signal to produce a microwave image (MI). The main drawback is that when the stroke is near the skull, it causes an increase in the skull-induced

In 2018, Lee et al. [32] used an IR-UWB radar for monitoring heart rate and rhythms (noncontact). Also, their result's reliability and validity with ordinary ECG are compared. The percentage of mean error is 2.3% vs. 0.2% of normal ECG, which

In 2018, Shen [33] used a IR-UWB radar to measure the respiration and heart beat rate. The study is based on the autocorrelation, that is, applying fast Fourier transform (FFT) to obtain the respiration rate easily, while reapplying the autocorrelation method after dividing the received signal to the sets of bins and removing one block is the resulting the heartbeat rate signal detection, where the pleural periodical movement caused by the periodicity is displayed as a drawback.

In 2019, Shyu et al. [34] proposed a UWB radar sensor to detect breathing and heart rate. They used First valley peak of the energy function of intrinsic mode functions (FVPIEF) based two-layer ensemble empirical mode decomposition (EEMD). This technique serves the feature time index to detect the frequency of heart beat rate equal to about 1 Hz, which is affected by separating the heart rate from the large breath rate (respiratory). The drawback of this technique is that the breathing movement always masks off the heart beat rate and it is still hidden in the

In 2019, Alghanimi et al. [35] proposed noninvasive blood glucose measurement depending on the relatively changing in the blood dielectric properties by using one ultra-wideband transceiver with a frequency range of 5GHZ and calculating the reflection coefficient through the comparison between the transmitted and

reflected signals; the drawback of this study is that there are many factors that can have an effect on the readings of that device like body temperature, gender, blood

In 2020, Alghanimi et al. [36] proposed an ultra-wideband radar for angiography by using two different types of antennas. The first antenna is placed around the human body and the other is inserted into the blood vessel in front of the guidewire of catheterizing angiography. The distance between antennas will be measured by calculating the time of arrival and propagation direction, which will be depending on the ultra-wideband frequency, shape, and other specifications. This distance between the antennas includes the human tissue with its different layers, where each layer has certain dielectric properties enabling us to recognize the tissue type. The drawback of this study is the difficulty of manufacturing a small UWB antenna

Many commonly used medical imaging devices for cardiovascular imaging has been found such as X-ray angiography, cardiac MRI, cardiac CT, and cardiac ultrasound (echo). These devices have some limitations such as radiographic exposure,

where the length be 7 mm and the antenna is operated as narrowband.

distortion and the system is complicated multi-input multi-output (MIMO).

means the UWB radar is inaccurate comparing with the normal ECG. The researchers used MATLAB program to synchronize and store radar readings with

normal ECG readings.

*Innovations in Ultra-WideBand Technologies*

large harmonics and noise.

that can be inserted into the human vessels.

**3. UWB medical radar for angiography**

group, and others.

**78**

The medical cardiovascular imaging UWB radar is a new approach for medical multi-static radar which depends on the use of two different transceivers. The first transceiver is a horn type that has been built around the body of angiography (encloses the human body), while the other is a micro-strip which has been inserted into the human blood vessel with the angiography guidewire. The wave pulses of medical radar traveled through the human tissues and then arrived at the receiver. According to the high dielectric properties, differences among the human tissues, and the blood, the radar can recognize the blood in the vessels, where the high percentage of water tissues (like blood) has high dielectric properties in comparison with other tissues. Also, the reflection coefficients' amplitude and time of peaks have been affected by the depth of blood vessels, thus making the ultra-wideband radar so favorable for cardiovascular imaging. The formation of the medical image is required for the finding of the distance between the two antennas, the propagation direction (Ө), and the time of arrival (TOA), which will be different from one tissue to another, depending on the dielectric properties (permittivity) of the tissue. The wave pulses passing through tissues with high dielectric properties (like blood) will be faster than when it passes through tissues with low dielectric properties. Also, the layers (tissues) have been recognized, depending on the finding of reflection pulses at the time of arrival and propagation direction.

**Figure 4** illustrates the possible scenarios for wave propagation (transmission) through the body layers; these scenarios are explained in the conclusion. The new medical radar has been worked instead of the X-ray angiography. To minimize the biological side effects of X-ray RF, which provides accurate real-time imaging which is necessary at catheterization angiography operation for clear imaging, the new medical radar is designed according to the standard model IEEE 802.15.3a channel parameters that consider a fifth derivative Gaussian pulse ultra-wideband with a frequency center of 5 GHz. These pulses have been passed through a hypothetical medium (which represent the human tissues); this medium has been represented by the additive white Gaussian noise (AWGN) and medium gain with a certain delay, where the delay and propagation direction in real cases will depend on the tissues that are passed through. Finally, the received signal will be compared with the transmitted signal by using a cross-correlator. **Figure 5** illustrates this simulation, which represents the MATLAB simulation for the new medical radar with all proposed components.

#### **3.2 Medical radar equations**

UWB waves transmit through the body tissue layers (mediums) under electromagnetic wave propagation laws, where the velocity of waves are different from one to another layer according to the dielectric properties (permittivity) of this medium [34, 37]:

$$\mathbf{Vi} = \frac{c}{\sqrt{\mathbb{E}i}} \tag{4}$$

where Өin is the incident angle which must be greater than the critical angle [37]:

Here, Ө<sup>c</sup> is founded only if the wave transmits from a denser to a less dense layer. And to find the one-way distance between the two transceivers of our radar, we need to find the one-way distance of each layer individually and the distance for the first layer (d1), second layer (d2), and any layer (di) as the following [20]:

**<sup>d</sup>**<sup>1</sup> <sup>¼</sup> *<sup>l</sup>*<sup>1</sup>

**d2** ¼ d1 þ

**di** ¼ *di*�<sup>1</sup> þ

where ω is the frequency of the wave. The vertical offsets between the two

*<sup>t</sup>***<sup>1</sup>** <sup>¼</sup> *<sup>d</sup>***<sup>1</sup>** *c*

> *d***<sup>2</sup>** � *d***<sup>1</sup>** *v***1**

> > *di*–*di*�**<sup>1</sup>** *vi*�**<sup>1</sup>**

where Vi is the velocity of wave in the medium. Also, the most important law in

**<sup>1</sup>** <sup>þ</sup> <sup>Ϭ</sup> *w*Ԑ � �**<sup>2</sup>** h i**<sup>1</sup>**

where μ is the permeability, Ԑ is the permittivity, Ϭ is the conductivity, and ω is

the frequency of wave. Considering the human body tissues as lossy mediums, μ = μo μr, Ԑ = Ԑo Ԑr, Ϭ 6¼ 0, where μo is the permeability of free space, μ<sup>r</sup> is the relative permeability, Ԑ<sup>o</sup> is the permittivity of free space, Ԑ<sup>r</sup> is the relative permittivity, and the dielectric properties of free space are: permittivity Ԑ<sup>o</sup> = 8.854 x 10�<sup>12</sup> (F/m), permeability <sup>μ</sup><sup>o</sup> = 4<sup>π</sup> � <sup>10</sup>�<sup>7</sup> (H/m), and conductivity <sup>Ϭ</sup> = 0 [38]. Finally, there are other parameters that can be obtained from the intrinsic impedance, and

ffiffiffiffiffi μ*=*Ԑ p

**4**

*t***<sup>2</sup>** ¼ *t***<sup>1</sup>** þ

*ti* ¼ *ti*�**<sup>1</sup>** þ

our calculations is the intrinsic impedance ƞ for each layer (medium) [38]:

Ƞ ¼

where *l1, l2*, and *l*<sup>i</sup> are obtained from the following equations:

antennas (It) can be obtained by the equation:

**81**

Also, to find the time *t***1**, *t***2**, and *ti* for each layer:

ffiffiffiffiffiffiffiffiffiffiffiffi Ԑ*i* þ 1 Ԑ*i* ! r

*l*2

*li*

sin ð Þ *<sup>Ө</sup>in* (7)

sin ð Þ *<sup>Ө</sup>t*<sup>1</sup> (8)

sin ð Þ <sup>Ө</sup>*t*<sup>2</sup> (9)

*l***<sup>1</sup>** ¼ w0 tan ð Þ *Өin* (10) *l***<sup>2</sup>** ¼ w1 tan ð Þ *Өt***<sup>1</sup>** (11) *li* ¼ wi tan ð Þ *Өti*�**<sup>1</sup>** (12)

*lt* ¼ *l***<sup>1</sup>** þ *l***<sup>2</sup>** þ *l***<sup>3</sup>** … *:* þ *li* (13)

(6)

(14)

(15)

(16)

(17)

**<sup>Ө</sup><sup>c</sup>** <sup>¼</sup> *sin* �<sup>1</sup>

*Medical Application of Ultra-Wideband Technology DOI: http://dx.doi.org/10.5772/intechopen.93577*

**Figure 4.** *Distance between two antennas with the including layers.*

**Figure 5.** *MATLAB simulation for the proposed UWB medical radar.*

where Vi is the velocity in layer i, c is the velocity in free space, and Ԑ<sup>i</sup> is the permittivity of the medium. The transmitted angle between two layers will be different from medium to another depending on the intrinsic impedance of the two mediums ƞ<sup>o</sup> and ƞ<sup>i</sup> and as in **Figure 3** and in [20]:

$$
\Theta \text{ti} - 1 = \sin^{-1} \left( \frac{\eta o}{\eta i} \sin \left( \Theta \dot{m} \right) \right) \tag{5}
$$

*Medical Application of Ultra-Wideband Technology DOI: http://dx.doi.org/10.5772/intechopen.93577*

where Өin is the incident angle which must be greater than the critical angle [37]:

$$\boldsymbol{\Theta}\mathbf{c} = \sin^{-1}\left(\sqrt{\frac{\xi i + 1}{\xi i}}\right) \tag{6}$$

Here, Ө<sup>c</sup> is founded only if the wave transmits from a denser to a less dense layer. And to find the one-way distance between the two transceivers of our radar, we need to find the one-way distance of each layer individually and the distance for the first layer (d1), second layer (d2), and any layer (di) as the following [20]:

$$\mathbf{d1} = \frac{l\mathbf{1}}{\sin\left(\Theta in\right)}\tag{7}$$

$$\mathbf{d}\_2 = \mathbf{d}\_1 + \frac{l2}{\sin\left(\Theta \mathbf{t} \mathbf{1}\right)}\tag{8}$$

$$\mathbf{d}\_{i} = d\_{i-1} + \frac{li}{\sin\left(\Theta t2\right)}\tag{9}$$

where *l1, l2*, and *l*<sup>i</sup> are obtained from the following equations:

$$l\_1 = \mathbf{w}\_0 \cdot \tan \left(\Theta\_{\text{in}}\right) \tag{10}$$

$$l\_2 = \mathbf{w}\_1 \cdot \tan \left(\Theta\_{t\mathbf{1}}\right) \tag{11}$$

$$I\_{\mathbf{i}} = \mathbf{w}\_{\mathbf{i}} \cdot \tan \left( \Theta\_{\mathbf{i}\mathbf{i}-\mathbf{1}} \right) \tag{12}$$

where ω is the frequency of the wave. The vertical offsets between the two antennas (It) can be obtained by the equation:

$$l\_t = l\_1 + l\_2 + l\_3 \dots + l\_i \tag{13}$$

Also, to find the time *t***1**, *t***2**, and *ti* for each layer:

$$\mathbf{t}\_1 = \frac{d\mathbf{1}}{\sigma} \tag{14}$$

$$t\_2 = t\_1 + \frac{d\_2 - d\_1}{v\_1} \tag{15}$$

$$t\_i = t\_{i-1} + \frac{d\_{i-d\_{i-1}}}{v\_{i-1}} \tag{16}$$

where Vi is the velocity of wave in the medium. Also, the most important law in our calculations is the intrinsic impedance ƞ for each layer (medium) [38]:

$$\left[\mathbf{I}\right] = \frac{\sqrt{\mu\_{\hat{\mathcal{K}}}}}{\left[\mathbf{1} + \left(\frac{\mathbf{G}}{w\hat{\mathcal{K}}}\right)^2\right]^{\frac{1}{\pi}}} \tag{17}$$

where μ is the permeability, Ԑ is the permittivity, Ϭ is the conductivity, and ω is the frequency of wave. Considering the human body tissues as lossy mediums, μ = μo μr, Ԑ = Ԑo Ԑr, Ϭ 6¼ 0, where μo is the permeability of free space, μ<sup>r</sup> is the relative permeability, Ԑ<sup>o</sup> is the permittivity of free space, Ԑ<sup>r</sup> is the relative permittivity, and the dielectric properties of free space are: permittivity Ԑ<sup>o</sup> = 8.854 x 10�<sup>12</sup> (F/m), permeability <sup>μ</sup><sup>o</sup> = 4<sup>π</sup> � <sup>10</sup>�<sup>7</sup> (H/m), and conductivity <sup>Ϭ</sup> = 0 [38]. Finally, there are other parameters that can be obtained from the intrinsic impedance, and

where Vi is the velocity in layer i, c is the velocity in free space, and Ԑ<sup>i</sup> is the permittivity of the medium. The transmitted angle between two layers will be different from medium to another depending on the intrinsic impedance of the two

> <sup>ƞ</sup>*<sup>i</sup>* sin ð Þ <sup>Ө</sup>*in*

(5)

**<sup>Ө</sup>t**<sup>i</sup> � <sup>1</sup> <sup>¼</sup> *sin* �<sup>1</sup> <sup>ƞ</sup>*<sup>ο</sup>*

mediums ƞ<sup>o</sup> and ƞ<sup>i</sup> and as in **Figure 3** and in [20]:

*MATLAB simulation for the proposed UWB medical radar.*

*Distance between two antennas with the including layers.*

*Innovations in Ultra-WideBand Technologies*

**Figure 5.**

**80**

**Figure 4.**

these parameters are reflection (Γ) and transmission (Γ) coefficients between mediums [34, 39]:

$$\Gamma\_{\mathbf{1}/2} = \frac{\eta\_{\mathbf{2}} - \eta\_{\mathbf{1}}}{\eta\_{\mathbf{2}} + \eta\_{\mathbf{1}}} \tag{18}$$

$$\mathbf{T\_{1}}\_{1} = \frac{\mathbf{2}\mathbf{\eta\_{2}}}{\mathbf{\eta\_{2}} + \mathbf{\eta\_{1}}} \tag{19}$$

Finally, the amplitude of transmitted wave (*Ex*) will decrease (attenuate) exponentially and can be obtained from the equation:

$$E\_{\mathfrak{x}} = \mathfrak{e}^{a\mathfrak{x}} \tag{20}$$

where *x* is the crossing distance and *a* is the attenuation coefficient, while the equations of this wave after incidents at the boundary between the two mediums with different dielectric properties will be:

$$E\_t = T.E\_i \tag{21}$$

tissues which are listed in **Table 1**. The thickness of these layers (tissues) are taken

**Permittivity Ԑ (F/m)**

Skin 3.06 35.774 42.7032786 0.24488786 Fat 0.24 5.0291 138.539578 1.17884328 Muscle 4.04 49.54 36.9706969 0.21196925 Bone 0.96 16.05 72.5312559 0.74134990 Heart 4.86 50.27 34.2849767 0.88705125 Blood 5.4 53.95 32.6208079 0.17272680 Lung 3.94 44.859 37.7366007 0.06408701

Air 1E-20 1 376.734309

**Intrinsic impedance ƞ(Ω)** **transmission angle Өt**

From the results shown in **Table 2**, the variations in the times and speeds for the layers have been observed and are based on the dielectric properties of each layer. These differences will enable the medical image reconstruction depending on the

The reflection coefficient and transmission coefficient with different frequen-

From the results which are illustrated in **Figures 6** and **7**, note that the reflection and transmission coefficients have a directional relationship with the frequency of a transmitted wave; and from **Figure 6**, note that the blood has the lowest reflection coefficients, which means the ultra-wideband pulses spend shorter time passing through the blood. Also, the transmission coefficient of skin-air is smaller than the transmission coefficient of air-skin, so improving the reflection and transmission coefficients increases the ability of the radar imaging process in any direction either from the inside to the outside transceiver or from the outside to the inside trans-

The radar can make the two processes together for getting a very clear image, which makes the new radar pass the problems of previous radars, which have been

**Tissue type Thickness L Distance Time Velocity** Air 50 50 58.76 2E-07 3E+08 Skin 1.3 0.32 60.1 2.2E-07 5E+07 Fat 9.5 22.98 84.97 4.1E-07 1E+08 Muscle 13.5 2.91 98.78 7.3E-07 4E+07 Bone 6.6 6.04 107.7 8.5E-07 7E+07 Heart 5.65 6.93 117.9 1.1E-06 4E+07 Blood 1.2 0.209 108.9 8.7E-07 4E+07 Lung 5.7 0.37 123.6 1.2E-06 4E+07

in the thorax area and ordered as shown in **Figure 4**.

**Conductivity Ϭ (S/m)**

*Medical Application of Ultra-Wideband Technology DOI: http://dx.doi.org/10.5772/intechopen.93577*

*3.3.3 Reflection and transmission coefficient calculation*

speed of waves in the tissues.

*Dielectric properties of human tissues.*

**Tissue type**

**Table 1.**

**Table 2.**

**83**

cies are illustrated in **Figures 6** and **7**.

ceiver, as illustrated in **Figure 4**.

*Distance and time between the layers.*

$$E\_r = \Gamma.E\_i \tag{22}$$

where *Ei* is the incident wave, *Et* is the transmitted wave, *Er* is the reflected wave, T is the transmission coefficient, and Γ is the reflection coefficient.

The dielectric properties of human body tissue are estimated by Gabriel [40, 41], so the thicknesses of the tissues (layers) in any region of the human body are represented in [42]. The equations above can be applied on the human body layers depending on the characteristic properties of each tissue which are dependent on the transmitted wave frequency.

#### **3.3 Results and discussion**

The above equations have been applied on the human body tissues based on the characteristic properties of the tissues which are dependent on the frequency of transmitted wave.

#### *3.3.1 Intrinsic impedance and transmission angle calculation*

The transmission angle between the tissues and the intrinsic impedance of human tissues is calculated as shown in **Table 1**, using a frequency center of 5 GHz, the incident angle of π/4, and based on the permittivity and conductivity (dielectric properties) of all tissues. Here, the intrinsic impedance has a directional relationship with the transmitted wave frequency, while the transmission angle has an inverse relationship with the frequency of the transmitted wave, and also it is based on the intrinsic impedance and the incident angle.

The results in **Table 1** are essential for time, distance, and speed calculation, which are essentially for the tissue recognition needed for image reconstruction, as mentioned in Section 3.2.

#### *3.3.2 Distance and time calculations*

The velocity, time, and the distance between the two transceivers (one-way distance) have been calculated by using the characteristic properties of human
