**2.1 Double-layer printed wearable dipole antennas**

Single-layer printed dipole antennas have a narrow bandwidth less than 1% for VSWR better than 2:1. The length of the dipole may be between quarter wavelength to half wavelength. The antenna directivity is around 0 dBi and the beam width is around 90°–100°. The antenna bandwidth may be improved by printing the antenna feed network on a dielectric substrate and by printing the radiating dipole on a second layer. The electromagnetic fields are coupled to the radiating dipole. The bandwidth of the double-layer printed dipole may be between 1 and 5% for VSWR better than 2:1 as a function of the dipole configuration and the layers thickness. The printed dipole antenna consists of two layers. The first layer consists of a 0.8-mm substrate with 3.5 as dielectric constant. The second layer consists of a 0.8-mm substrate with 2.2 as dielectric constant. The substrate thickness

*Wideband Wearable Antennas for 5G, IoT, and Medical Applications DOI: http://dx.doi.org/10.5772/intechopen.93492*

determines the antenna bandwidth. However, thinner antennas are flexible. The antenna dimensions are designed to operate on the patient's body by using electromagnetic software [50]. The double-layer antenna is shown in **Figure 1**. The directivity of the antenna at 420 MHz is around 4 dBi as shown in **Figure 2**.

A double-layer 460 MHz dipole antenna is shown in **Figure 3**. The antenna dimensions are 20 4 cm. The directivity of the antenna at 460 MHz is around 5 dBi as presented in **Figure 4**. The antenna beamwidth is around 120°.

**Figure 1.**

portable RF antennas is studied in [16]. In this chapter, the authors determine that the antennas' length in free space is larger by 10–20% from the length of wearable antennas. Measurement of the antenna gain in this paper shows that a wide dipole (1.16 0.1 m) has 13 dBi gain. Wearable antennas for cellular applications are presented in [12–16]. Electrical specifications of medical devices are different from the electrical specifications for cellular devices. Medical wearable sensors are presented in [21–48]. Wearable devices support the development of personal medical sensors and systems with real-time response to help improve patient's health. Wearable medical sensors and devices can measure the sweat rate, body temperature, heartbeat, and blood pressure, perform gait analysis, and measure other body health parameters of the patient wearing these sensors, see Refs. [21–49]. In this chapter, novel wideband compact wearable antennas for 5G communication and medical systems are presented. Numerical results in free space and near the human

*Advanced Radio Frequency Antennas for Modern Communication and Medical Systems*

**2. Printed wearable antennas for 5G and medical applications**

Wearable antennas should be compact, have lightweight, are low cost, and are flexible. Microstrip antennas, printed loops, printed dipoles, slot antennas, and PIFA antennas are compact, low cost, conformable, and have lightweight. These antennas are a good choice to be employed as wearable antennas for IoT and medical applications.

Single-layer printed dipole antennas have a narrow bandwidth less than 1% for VSWR better than 2:1. The length of the dipole may be between quarter wavelength to half wavelength. The antenna directivity is around 0 dBi and the beam width is around 90°–100°. The antenna bandwidth may be improved by printing the antenna feed network on a dielectric substrate and by printing the radiating dipole on a second layer. The electromagnetic fields are coupled to the radiating dipole. The bandwidth of the double-layer printed dipole may be between 1 and 5% for VSWR better than 2:1 as a function of the dipole configuration and the layers thickness. The printed dipole antenna consists of two layers. The first layer consists of a 0.8-mm substrate with 3.5 as dielectric constant. The second layer consists of a

0.8-mm substrate with 2.2 as dielectric constant. The substrate thickness

body are presented.

• Medical

• IoT

• WLAN

• GPS

**22**

• HIPER LAN

• Military Applications

**2.1 Double-layer printed wearable dipole antennas**

**Applications of wearable antennas:**

• 5G Communication Systems

• Wireless Communication

*Wearable double-layer 420 MHz printed dipole antenna.*

**Figure 2.** *Radiation pattern of a wearable double-layer printed dipole antenna.*

**Figure 3.** *Wearable double-layer 460 MHz printed dipole antenna.*

is around 2 dBi. The simulated S11 and S22 parameters are shown in **Figure 6**. **Figure 7** presents the antenna's measured S11 parameters. The simulated radiation patterns are shown in **Figure 8**. There is a good agreement between the measured and computed results. The co-polar radiation is in the yz plane. The cross-polar radiation is in the xz plane. The antenna cross-polarization value may be adjusted by varying the feed lines and matching stubs' locations. The dimensions and current distribution of the folded antenna are shown in **Figure 9**. The radiating element

*Current distribution of the dual-polarized wearable antenna.*

*Wideband Wearable Antennas for 5G, IoT, and Medical Applications*

*DOI: http://dx.doi.org/10.5772/intechopen.93492*

*Computed S11 and S22 results of the dual-polarized dipole on human body.*

*Measured S11 of the wearable dual-polarized dipole antenna on human body.*

**Figure 5.**

**Figure 6.**

**Figure 7.**

**25**

**Figure 4.** *Radiation pattern of a wearable double-layer printed dipole at 460 MHz.*

### **3. Printed wearable dual-polarized dipole antennas**

In several communication and medical systems, the polarization of the received signal is not known. The polarization of the received signal may be vertical, horizontal, or circular polarized. In these systems, it is crucial to use dual-polarized receiving antennas. Two wearable antennas are presented in this section; the first is a dual-polarized printed dipole. The second antenna is a dual-polarized, folded, printed microstrip dipole. The compact, printed, loaded dipole antenna is horizontally polarized. The antenna dimensions have been designed to operate on the patient's body by employing electromagnetic software [50]. The antenna consists of two layers. The first layer consists of a 0.08-cm dielectric substrate with 3.5 as relative dielectric constant. On this layer, the antenna feed network is printed. The radiating elements are printed on the second layer which consists of a 0.08-cm dielectric substrate with 2.2 as relative dielectric constant. Thicker antennas have a wider bandwidth. However, thinner antennas are more flexible with a narrower bandwidth. The printed slot antenna is vertically polarized. The printed dipole and the slot antenna provide dual orthogonal polarizations. The wearable antenna current distribution and dimensions are shown in **Figure 5**.

The radiating dipole dimensions are 21 4 0.16 cm. The wearable antenna may be employed in medical and IoT systems. The antenna may be attached to the patient clothes, in the front or in the back zone. The antenna has been analyzed by using Key-sight momentum software [50]. The antenna bandwidth is around 15% for VSWR better than 3:1. The antenna 3 dB beamwidth is 100°. The antenna gain *Wideband Wearable Antennas for 5G, IoT, and Medical Applications DOI: http://dx.doi.org/10.5772/intechopen.93492*

**Figure 5.**

**3. Printed wearable dual-polarized dipole antennas**

*Radiation pattern of a wearable double-layer printed dipole at 460 MHz.*

**Figure 4.**

**24**

rent distribution and dimensions are shown in **Figure 5**.

In several communication and medical systems, the polarization of the received signal is not known. The polarization of the received signal may be vertical, horizontal, or circular polarized. In these systems, it is crucial to use dual-polarized receiving antennas. Two wearable antennas are presented in this section; the first is a dual-polarized printed dipole. The second antenna is a dual-polarized, folded, printed microstrip dipole. The compact, printed, loaded dipole antenna is horizontally polarized. The antenna dimensions have been designed to operate on the patient's body by employing electromagnetic software [50]. The antenna consists of two layers. The first layer consists of a 0.08-cm dielectric substrate with 3.5 as relative dielectric constant. On this layer, the antenna feed network is printed. The radiating elements are printed on the second layer which consists of a 0.08-cm dielectric substrate with 2.2 as relative dielectric constant. Thicker antennas have a wider bandwidth. However, thinner antennas are more flexible with a narrower bandwidth. The printed slot antenna is vertically polarized. The printed dipole and the slot antenna provide dual orthogonal polarizations. The wearable antenna cur-

*Advanced Radio Frequency Antennas for Modern Communication and Medical Systems*

The radiating dipole dimensions are 21 4 0.16 cm. The wearable antenna may be employed in medical and IoT systems. The antenna may be attached to the patient clothes, in the front or in the back zone. The antenna has been analyzed by using Key-sight momentum software [50]. The antenna bandwidth is around 15% for VSWR better than 3:1. The antenna 3 dB beamwidth is 100°. The antenna gain

*Current distribution of the dual-polarized wearable antenna.*

is around 2 dBi. The simulated S11 and S22 parameters are shown in **Figure 6**. **Figure 7** presents the antenna's measured S11 parameters. The simulated radiation patterns are shown in **Figure 8**. There is a good agreement between the measured and computed results. The co-polar radiation is in the yz plane. The cross-polar radiation is in the xz plane. The antenna cross-polarization value may be adjusted by varying the feed lines and matching stubs' locations. The dimensions and current distribution of the folded antenna are shown in **Figure 9**. The radiating element

**Figure 7.** *Measured S11 of the wearable dual-polarized dipole antenna on human body.*

**Figure 8.** *Radiation pattern of the dual-polarized wearable antenna.*

**Figure 9.** *Current distribution of the folded wearable dipole antenna, 6 5 0.16 cm.*

dimensions are 55 40 1.6 mm. **Figure 10** presents the antenna's simulated S11 and S22 parameters. The folded dipole radiation pattern is shown in **Figure 11**. The antennas' radiation characteristics on human body were measured by using a phantom. The phantom liquid presents the body tissue's electrical characteristics. The phantom diameter is 40 cm and has 1.5 m length. The phantom liquid is a mix of 55% water, 44% sugar, and 1% salt. The wearable antenna was placed on the phantom during the measurements of the antenna's electrical characteristics. S11 and S12 parameters were measured on the patient's body by using a network

**4. Wearable microstrip antennas for 5G, medical, and IoT applications**

Printed antennas are usually low profile, compact, flexible, light weight, and low-cost relative to wired antennas. Microstrip antennas may be used as wearable antennas. Printed antennas have been widely presented in the literature in the last 20 years, [1–19]. The most popular type of printed antennas is the microstrip

analyzer. Photo of wearable antennas is shown in **Figure 12**.

**Figure 11.**

**Figure 12.**

**27**

*Photo of wearable antennas.*

*Radiation pattern of the folded dual-polarized antenna.*

*DOI: http://dx.doi.org/10.5772/intechopen.93492*

*Wideband Wearable Antennas for 5G, IoT, and Medical Applications*

**Figure 10.** *Folded antenna's computed S11 and S22 results on human body.*

*Wideband Wearable Antennas for 5G, IoT, and Medical Applications DOI: http://dx.doi.org/10.5772/intechopen.93492*

**Figure 11.** *Radiation pattern of the folded dual-polarized antenna.*

**Figure 8.**

**Figure 9.**

**Figure 10.**

**26**

*Radiation pattern of the dual-polarized wearable antenna.*

*Advanced Radio Frequency Antennas for Modern Communication and Medical Systems*

*Current distribution of the folded wearable dipole antenna, 6 5 0.16 cm.*

*Folded antenna's computed S11 and S22 results on human body.*

**Figure 12.** *Photo of wearable antennas.*

dimensions are 55 40 1.6 mm. **Figure 10** presents the antenna's simulated S11 and S22 parameters. The folded dipole radiation pattern is shown in **Figure 11**. The antennas' radiation characteristics on human body were measured by using a phantom. The phantom liquid presents the body tissue's electrical characteristics. The phantom diameter is 40 cm and has 1.5 m length. The phantom liquid is a mix of 55% water, 44% sugar, and 1% salt. The wearable antenna was placed on the phantom during the measurements of the antenna's electrical characteristics. S11 and S12 parameters were measured on the patient's body by using a network analyzer. Photo of wearable antennas is shown in **Figure 12**.
