1. Introduction

Compact resonators and antennas are presented in [1, 2, 3, 4, 5, 6]. The efficiency of compact resonators is low. Several types of compact wearable antennas, such as printed dipoles and microstrip antennas, are presented in [2, 3, 4, 5, 6]. Printed metamaterial sensors are employed in wireless communication systems and were presented in several publications, see [2, 3, 4, 5, 6, 7]. Materials with periodic artificial structures are called metamaterials. The metamaterial structure and components define the electrical properties of the material. In [8, 9, 10, 11, 12, 13, 14] metallic posts structures and periodic split-ring resonators (SRRs) are used to produce structures with required permeability and dielectric constant. Metamaterials may be employed to develop efficient sensors for RF, medical and IoT wearable devices [12, 13, 14, 15, 16]. The bandwidth and gain of the antenna presented in [8] are like those of patch antennas. Materials with negative dielectric permittivity are described in [9]. A model and setup to compute and measure the polarity of SRRs are described in [10]. A dual-band transmission-line metamaterial antenna with two transmission-line arms is described in [14]. The radiation efficiency of the antenna at 3.3 GHz is around 60% with 2.6 dBi directivity, and 0.8 dBi gain. Antennas such as patches, loops, and FIPA antennas have low efficiency [2, 3, 4, 5, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]. In communication and healthcare systems, the system polarization may be vertical, horizontal, or elliptical. In these systems, the radiating elements must be circular or dual-polarized. In [15, 16, 17] compact metamaterials sensors for healthcare devices are presented. Measurements of wearable sensors are presented in [19]. Active antennas for communication, medical, and IoT devices are presented in [20]. As presented in [30] Wearable healthcare devices are used to increase disease cure and prevention. A wireless device with thermal-aware protocol is presented in [30]. Wearable sensors and antennas for healthcare and RF systems are presented in [31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41]. Dual-polarized wearable antennas for healthcare applications are presented in [41]. Dual polarized metamaterial antennas have significant advantages over regular printed antennas, such as high efficiency and gain. The sensors electrical parameters on and near the human body were evaluated, see [2, 3, 4, 5, 6], by employing RF CAD software [42, 43].

In this chapter, metamaterials technology is used to develop high-efficiency sensors and antennas with harvesting energy units for medical, communication, and IoT devices. The energy harvesting units connected to the system provide compact self-powered efficient sensors.

The antennas bandwidth is around 20 to 45%, for VSWR, better than 3:1. The gain of the antennas with CSRRs is around 7.5 dB. The sensors efficiency is higher than 90%.

2. Wearable technologies and devices

Wearable systems and devices will be in the next following years, an important part of individuals’ daily lives. Wearable healthcare systems may measure and record several medical parameters such as heartbeat rate, blood pressure, sweat rate, arterial blood pressure, body temperature, electrocardiograms, and electro-dermal activity. Wearable devices may provide monitoring and scanning features that are not provided by cellular phones and other computing devices. Wireless devices and technologies are employed to analyze and process the data collected by the healthcare devices. The collected medical information may be transmitted to the healthcare center to analyze the collected medical information. This process may send a message to the physician to call the patient that needs immediate medical treatment.

2.1 Features of wearable healthcare and sport devices

Healthcare wearable systems monitor healthcare centers daily activities.
Wearable systems monitor and operate companies’ daily activities and systems.
Healthcare wearable systems assist and help patients such as Asthma patients, Diabetes patients, Alzheimer’s disease patients and Epilepsy patients.
Healthcare wearable systems and devices may help to solve Obesity problems, Sleep disorders, and cardiovascular diseases.

Wearable healthcare systems may measure and record several medical parameters such as heartbeat rate, blood pressure, sweat rate, arterial blood pressure, body temperature, electrocardiograms, and electro-dermal activity. The application of WBANs in medical centers with energy harvesting units, where the medical parameters of a large number of patients are constantly being monitored, is presented in Figure 1.

Figure 1.
Green wireless body area network, WWBAN, health monitoring sensors and system with energy harvesting units.

2.2 IoT systems

IoT devices are wireless communication modules of interrelated computing systems, mechanical machines, personal devices, healthcare sensors, and digital machines that possess unique identifiers (UIDs). IoT devices and systems consist of wireless communication modules, processors, sensors, and radiating elements. IoT devices and systems transmit, receive, and process data from networks connected to the Internet web. IoT devices and systems are connected to an IoT gateway network where they gather data that is analyzed online or sent to information centers to be processed and shared with specific IoT modules and devices. The polarization of the receiving channel of IoT and medical devices should match the polarization of the transmitting channel. In several communication devices, the polarization is not defined. In these cases, the receiving antenna should be dual-polarized. IoT systems are significant in daily work and treatment in healthcare centers. IoT modules and systems may connect several healthcare devices and healthcare information centers to improve healthcare treatment. Efficient medical and IoT systems result in low-cost healthcare treatment.

Efficient medical and IoT systems and devices are used to automate healthcare systems and procedures, to minimize organization and healthcare centers facilities and to lower labor costs.
IoT systems may transmit data through a communication system without the need of human to computer interaction or human-to-human involvement.
IoT systems can provide complete control over daily tasks and services in healthcare centers and organizations. IoT systems improve people’s daily life and help companies to function more efficiently and smarter.

A block diagram of IoT medical device is presented in Figure 2.

Figure 2.
IoT medical system block diagram.

IOT Devices and Systems Major Disadvantages-

In several IoT devices and systems modules and information are shared between several machines and devices. This fact increases the threat that hackers can steal confidential data and corrupt devices connected to this IoT system.
A bug in the IoT devices and system may corrupt devices and modules connected to this IoT system.

2.3 Wireless communication devices and cellular phones features

The first generation of cellular phones began in the 1980s and used 1G technology. 1G technology of mobile phones uses analog radio systems. In the last decade, communication technology was improved rapidly and is employed in modern mobile phones. Table 1 presents the improvement of mobile phone communication technologies.

Technology	1G	2G	3G	4G	5G
Data Speed	2.4 kbps	64 Kbps	3 Mbps	1Gbps	20 Gbps
Electronic Technology	Analog	Digital	Audio and video	Wi-Fi	Wi-Fi, wireless
Battery life	Few hours	Longer life cycle	Longer life cycle	Better life cycle	Power savings
Dimensions	Big and large	Smaller	Size reduction	Compact	Compact
Security	Low security	call and text encryption	Improved security	High security	High security
Capacity	Limited	Improved	Large	Large	High capacity

Table 1.

Comparison of cellular phone technologies.

5G Technology Main features

High data transmission speed and high capacity.
Connected and supportable to Wireless World Wide Web.
Large broadcasting of data in Gbps.
Observe TV programs with HD Clarity and read newspapers.
Improved information transmission than that of 4G Generation.
Better phone memory, improved dialing speed, improved clarity in audio and video features.
5G technology provides high resolution to cellular phone users and large bandwidth sharing.

3. Compact wearable dual polarized antenna for IoT and medical applications

The antenna with CSRR and metallic strips is presented in Figure 3a. The printed dipole matching network and the metallic strips are etched on the first layer with thickness of 0.16 cm. The radiating element with CSRR is printed on the second layer with thickness of 0.16 cm. The size of the antenna network with the energy harvesting module is 21.5×4.5 cm. The printed slot antenna is vertically polarized. The printed dipole is horizontally polarized. The resonant frequency of the dipole with CSRR is around 0.33GHz, which is lower by 15% than the resonant frequency of the printed dipole without CSRR. Many communications, IoT and healthcare systems operate in the frequency range between 0.1 and 0.55 GHz. The computed S11 and antenna gain are shown in Figure 4. The measured antenna bandwidth is around 45% for S₁₁ lower than -6 dB. The dipole and the slot radiate in the z axis direction. The measured directivity and gain of the antenna with CSRR are around 5.5 dBi, as presented in Figure 5. The feed network of the antenna in Figure 3a was optimized, see Figure 3b, to yield S11 lower than -6 dB in the frequency range from 0.18 to 0.4 GHz, around 60% bandwidth, as presented in Figure 6. The dimensions of the antennas presented in this chapter are given in Table 2.

Figure 3.
(a). Antenna with CSRR and with energy harvesting unit, (b). optimized sensor with CSSR and metallic strips.

Figure 4.
Gain and S11 of the dual-polarized antenna with metallic strips and CSRR.

Figure 5.
Radiation pattern and gain of the antenna with metallic strips and CSRR.

Figure 6.
S11 of the optimized dual-polarized antenna with metallic strips and CSRR on human body.

Antenna	Frequency (GHz)	BW %	Computed Gain dBi	Measured Gain dBi	Dimension (cm)	Efficiency %
Printed dipole with CSRR [2]	0.35	10	5.5	5.7	19.8×4.5	95
Dipole no CSRR [2]	0.4	10	2.5	2.5	21×4.5	90
Printed Loop	0.4–0.5	2	0	0	5 Diameter	Low
Active receiving loop	0.35–0.58	40	23 ± 2.5	22 ± 3	7 Diameter	50
Active transmitting loop	0.36–0.6	45	13 ± 3	12 ± 3	7 Diameter	50
Stacked circular patch without CSRR [15]	2.7	8	5.5	5.3	4.8 Diameters	90
Circular patch with CSRR [15]	2.63	8	7.5	7.8	3.6 Diameters	85
Circular patch without CSRR [1, 2]	2.63	1.5	4.5	4.3	4.8 Diameters	85

Table 2.

Electrical performance comparison between wearable antennas without and with CSRR.

The sensors electrical parameters, presented in this chapter, on and near the human body were evaluated, see [2, 3, 4, 5, 6, 7], by employing RF CAD software [42, 43]. The theoretical and equations used to design the sensors presented in this chapter are given in previous publications, see [2, 3, 4, 5, 6, 7]. The energy harvesting module is connected to the antenna network feed line, as presented in Figure 3. The energy harvesting module can charge the battery when the switch is connected to the harvesting unit. Electromagnetic AC power is converted to DC power by employing a rectifying diode. The rectifier may be a half-wave rectifier or a full-wave rectifier. As shown in Figure 3, the harvesting module has an antenna, a rectifying circuit, and may recharge the device battery.

4. Wearable self-powered active sensor

A receiving self-powered active sensor is presented in Figure 7. The energy harvesting module acts as a dual-mode electromagnetic harvesting module. A switch may connect the LNA to the energy harvesting module. The energy harvesting module charges the battery. The Low Noise Amplifier is matched to the receiving antenna via a matching network. The LNA TAV541 is a linear PHMET amplifier. At 2 GHz, the amplifier has 0.45 dB Noise Figure and 18.5 dB gain. The LNA P1dB, at 2 GHz, is 19 dBm at the output port. The LNA specifications are listed in Table 3. A DC bias network supplies the required voltages to the amplifiers. The Low Noise Amplifier is matched to the receiver via an output-matching network. The sensor dimensions are around 21.5×5×1.9 cm. Gain and reflection coefficient of the metamaterial sensor is presented in Figure 8. The receiving active sensor gain as presented in Figure 9 is 12 ± 3 dB, and the noise figure is better than 1 dB, for frequencies from 0.1GHz to 1GHz. The active metamaterial antenna was evaluated with Triquint LNA TQP3M9028. The amplifier specifications are given in Table 3. The active antenna gain with TQP3M9028 LNA is 11.1 ± 2.5 dB from 0.15 to 0.9GHz, as presented in Figure 10. The sensor noise figure, with TQP3M9028 LNA, for frequencies from 0.15GHz to 1GHz is better than 1.9 dB. The measured performance of the sensors with different LNAs is listed in Table 4. The active antennas with LNA TAV541 has better noise figure and higher gain. The sensor with LNA TQP3M9028 has a better 1dBc compression point and gain flatness.

Figure 7.
Dual polarized receiving sensor with CSRR and with energy harvesting unit.

Figure 8.
S11 and gain of the dual-polarized antenna with CSRR and matching network.

Specification	TAV541, Mini Circuit	TQP3M9028, Triquint
Frequency, GHz	0.4–3	0.05–4
Gain at 2 GHz	18.5 dB	14.5 dB
N.F at 2GHz	0.45 dB	18 dB
P1dB at 2GHz	18.5 dBm	20.5 dBm
OIP3 at 2GHz	32 dBm	35 dBm
Operating Temp.°C	−40 – 80	−40 – 80
Max. Input power	17 dBm	17 dBm
Vgs, Volt	0.4	0.4
Vds	3 V, Ids = 60 mA	5 V, Ids = 85 mA
Supply voltage, V	±5	±5
Package type	Surface Mount	Surface Mount

Table 3.

Comparison of the specification of the S-band low noise amplifiers.

Figure 9.
Active receiving dual polarized receiving sensor gain, with LNA.

Figure 10.
Active receiving dual polarized receiving sensor gain, with TQP3M9028 LNA.

Parameter	Sensor with TAV541	Sensor with TQP3M9028
Frequency	0.1–1 GHz	0.15–0.9 GHz
VSWR	3:1	3:1
Gain	11 ± 2.5 dB	12 ± 3 dB
N.F at 1GHz	1 dB	2 dB
P1dB at 1GHz	19.0 dBm	20 dBm
Max Input power	17 dBm	17 dBm
Vgs, Volt	0.5	0.5
Vds	3 V, Ids = 55 mA	5 V, Ids = 80 mA
Dimensions	21.5×5×1.9 cm	21.5×5×1.9 cm

Table 4.

Comparison of the sensors measured performance with different LNA Amplifiers.

5. Wearable self-powered active transmitting antenna

A transmitting self-powered active sensor is presented in Figure 11. The energy harvesting module acts as a dual-mode electromagnetic harvesting module. The harvesting module can be part of a healthcare, IOT, and cellular phone. A switch may connect the transmitter battery to the energy harvesting module. The energy harvesting module charges the battery. Two power amplifiers were used to develop the metamaterial active sensor. The first amplifier is an MMIC GaAs MESFET VNA25, the second amplifier is an MMIC GaAs PHEMT HMC459. The amplifier specification is listed in Table 5. A DC bias network supplies the required voltages to the amplifiers. The sensor dimensions are around 21.5×5×1.9 cm. The active transmitting sensor VSWR, computed and measured, is better than 3:1 for frequencies from 0.25 to 0.45GHz. The computed and measured antenna gain are around 5.8 dBi, as presented in Figure 12. The active computed and measured antenna gain with HPA VNA25 is 13 ± 3 dB 1 for frequencies from 0.1 to 0.8 GHz. The transmitting sensor S21 parameter is shown in Figure 13. The active computed and measured antenna gain with the HMC459 HPA is 12 ± 4 dB for frequencies from 0.1 to 1 GHz, as shown in Figure 14. The transmitting sensor output power is around 19.5 dBm. The measured electrical performance of the sensors with the HPAs is listed in Table 6. The active antenna with VNA25 HPA has better gain flatness, higher gain, and lower DC power consumption. The transmitting antenna with HMC459 HPA has higher input and output power, and higher 1 dBC compression point. The HPA HMC459 has wider bandwidth from 1 to 18GHz. Photos of the metamaterial sensors, with CSSR and metallic strips, are shown in Figure 15.

Figure 11.
Dual polarized transmitting sensor with CSRR and with energy harvesting unit.

Specification	VNA25, Mini Circuit	HMC459, Triquint
Frequency GHz	0.4–2.5	DC–18
Gain dB at 1.8 GHz	17.5	16.5
N.F at 1.8 GHz	5.0 dB	3.8 dB
P1dB at 1.8 GHz	18.5 dBm	24 dBm
Max Input power	10 dBm	16 dBm
OIP3 at 1.8 GHz	28 dBm	29 dBm
Vgs, V	0.5	0.5
Vds	5 V, Ids = 85 mA	8 V, Ids = 290 mA
Supply voltage, V	±5	±8
Package	Surface Mount	Surface Mount
Temp. Range °C	−40 – 80	−40 – 80

Table 5.

Electrical Specification of the HPA Amplifiers.

Figure 12.
Radiation pattern and gain of the dual-polarized antenna with metallic strips and CSRR.

Figure 13.
Active transmitting dual polarized sensor gain, with HPA VNA25.

Figure 14.
Active transmitting dual polarized sensor gain, with HPA HMC459.

Parameter	Sensor with VNA25	Sensor with HMC459
Frequency	0.1–1GHz	0.15–0.9 GHz
VSWR	3:1	3:1
Gain	13 ± 3 dB	12 ± 4 dB
N.F at 1 GHz	6 dB	5 dB
P1dB at 1 GHz	19.0 dBm	24 dBm
Max Input power	10 dBm	16 dBm
Vgs	0.50 V	0.50 V
Vds	5 V, Ids = 85 mA	8 V, Ids = 290 mA
Dimensions	21×6×2cm	21×6×2cm

Table 6.

Comparison of the sensors performance with different HPA amplifiers.

Figure 15.
Photos of the metamaterial antenna. a. Feed layer b. antenna with CSSRs c. CSSR.

6. Wearable metamaterial antennas for communication, healthcare, and IoT systems

The antenna’s electrical parameters performance near the human body were computed by employing the antenna and human body model presented in Figure 16a. The dielectric constant and conductivity of human body tissues are given in Table 7 [21, 22]. The effect of the antenna location on the human body is simulated by evaluating the antenna’s electrical parameters on human body. The variation of the dielectric constant of the body tissues affects the electrical performance of the antenna. The antenna resonant frequency may be shifted up to 10% at different locations of the antenna on the patient’s body. As shown in Table 7, the dielectric constant of fat tissues is 4.7, 41 in the skin tissues, 43 in the stomach area, and up to 128.1 in the small intestine tissues. The antennas may be placed inside a belt, as shown in Figure 16b. The antenna’s electrical characteristics were computed and measured for air spacing between the sensors and human body up to 25 mm at different locations on the human body. Measurements of wearable sensors and antennas are done by using a phantom with sugar, salt, and water that represent the dielectric constant and conductivity of human body tissues [2, 3, 4, 5, 19]. The antenna’s electrical and mechanical characteristics were optimized to achieve the best antenna electrical and mechanical performance. Wearable antennas and sensors measurements and setup are discussed in [2, 3, 4, 5, 19].

Figure 16.
(a) Model of wearable antenna environment; (b) wearable medical system on human body.

Tissue	Parameter	440 MHz	600 MHz	1 GHz	1.25 GHz
Fat tissues	σ	0.047	0.05	0.054	0.06
Fat tissues	ε	5.00	5.00	4.72	4.55
Stomach tissues	σ	0.71	0.75	0.96	0.98
Stomach tissues	ε	42.7	41.40	39.66	39.00
Blood	σ	1.76	1.78	1.91	1.99
Blood	ε	57.2	56.5	55.40	55.00
Skin	σ	0.58	0.6	0.63	0.77
Skin	ε	41.6	40.45	40.25	39.65
Lung tissues	σ	0.27	0.27	0.27	0.28
Lung tissues	ε	38.4	38.4	38.4	38.4
Kidney tissues	σ	0.90	0.90	0.90	0.91
Kidney tissues	ε	117.45	117.45	117.45	117.45
Colon tissues	σ	1.00	1.05	1.30	1.45
Colon tissues	ε	63.5	61.9	60.00	59.40
Small intestine	σ	1.74	1.74	1.74	1.74
Small intestine	ε	128.1	128.1	128.1	128.1

Table 7.

Electrical parameters of human body tissues [16, 17].

Table 2 presents a comparison between computed and measured results of sensors without and with CSRR. Table 8 presents a comparison of computed and measured results of compact wearable antennas.

Input Power dBm	Efficiency %	Remarks
−4−−6	8–12	Low Efficiency
−3−−2	28–32	Low Efficiency
−1 − +1	48–52	Good Efficiency
2–3	52–56	Good Efficiency
4–5	52–56	Good Efficiency
6–8	56–58	Good Efficiency
9–11	60–65	Best Efficiency

Table 8.

Measured harvester efficiency as function of input collected power.

Tables 2 and 8 verify that there is a good match between computed and measured results. Electrical performance of several passive and active antennas (such as dipoles, loop, slot and other antennas) is discussed in [2, 3, 4, 5, 6]. Medical, wearable wireless BAN, IoT, and monitoring systems with wearable BAN systems are shown in Figure 17. Hospitals, Health care centers and medical staff can be contacted from everywhere at any given time.

Figure 17.
Green medical, WWBAN, and IoT monitoring system with WBAN networks with energy harvesting units.

7. Electromagnetic energy harvesting concept

As presented in Figure 3, the energy harvesting unit consists of an antenna, rectifying diode and circuit, and a rechargeable battery. The energy harvesting unit and the radiating element provide a self-powered device. The rectifier diode converts electromagnetic energy, AC energy, to direct current (DC energy). Two types of diode rectifiers are usually used a half-wave rectifier or a full-wave rectifier [44, 45, 46, 47]. A half-wave rectifier is presented in Figure 18. A half-wave rectifier converts only the half cycle of the positive voltage. It allows harvesting only one-half of the electromagnetic wave. The efficiency of the half-wave rectifier is around 41%. A full-wave bridge rectifier is shown in Figure 19. The bridge full-wave diode rectifier circuit converts electromagnetic energy to DC energy. The bridge rectifier consists of four diodes D1 through D4, as shown in Figure 19. The rectifier output DC voltage, VODC=2Vm/π. By connecting a capacitor in shunt to the resistor, as shown in Figure 19, the rectifier output voltage may be improved. The full-wave rectifier efficiency is around 81%. Electromagnetic power amount in public centers, stadiums, hospitals, and malls may range from 1 μW/cm² to 5 mW/cm². The harvesting system efficiency increases as function of the electromagnetic power collected by the harvesting system, as listed in Table 8. The amplifier amplifies the input power collected by the energy harvesting system and improves the efficiency of the harvesting system. Results listed in Table 8 are also presented by companies that manufacture commercial RF energy harvesting systems, see [2, 3, 4, 5, 6, 7, 44, 45, 46, 47]. If the RF radiating sources are close to the harvesting system, the RF power collected by the harvester will be higher.

Figure 18.
Diode voltage rectifier with a capacitor, half wave.

Figure 19.
Diode bridge voltage rectifier with a capacitor, full wave.

Energy harvesting units provide green renewable energy and may eliminate the usage of power cords and the need to replace batteries frequently. Wearable medical devices with energy harvesting modules for wireless communication, IoT, and medical applications are presented in Figure 20. As presented in Figure 20, the medical device and harvesting module with a compact battery charger are located on the patient’s shirt.

Figure 20.
Wearable RF system with energy harvesting unit for IoT, 5G, and healthcare systems.

In 2022 almost everyone uses cellular phones, communication networks, tablets, and other RF communication systems. There is a huge increase in the amount of RF energy in the air. The expected amount of radio waves in the air in 2022 was around 60 Exa-bytes, EB, per month. The expected amount of RF energy in the air in 2025 is expected to be around 170 Exa-bytes per month. In RF energy harvesting modules, the radio frequency waves propagating in air can be received by the antennas and converted to DC power that is employed to charge batteries, sensors, and other wearable devices.

8. Conclusions

The active and passive sensors and metamaterials antennas presented in this chapter are wideband, efficient, compact, and low-cost. RF energy harvesting modules are connected to the antennas and sensors. Electromagnetic waves propagating in the air can be collected by the antennas and converted to DC power that may recharge the healthcare, computing system batteries, wearable sensors, and other RF modules. Evaluation of efficient active and passive wearable antennas and sensors is one of the most significant goals in the evaluation of wearable healthcare devices, medical sensors, IoT, wireless communication and medical systems. Passive and active metamaterial compact antennas and sensors characteristics such as gain, matching, noise figure, efficiency, bandwidth, and radiation pattern are presented in this chapter. The directivity and gain of the sensors with CSRRs are higher by 2.5 dB than the sensors without CSRRs. For S11 lower than -6 dB the bandwidth of the novel metamaterial sensors may be around 15 to 55%. The directivity and gain of the new metamaterial passive sensors are around 5 to 7.5 dBi. The receiving active sensor gain is 12 ± 3 dB. The transmitting active sensor gain is 13 ± 3 dB.

The metamaterial antennas and sensors discussed in this research may be used in wireless communication devices, computing networks, IoT devices, sport, and medical applications. Metamaterial technology is employed to design compact, efficient antennas and sensors. The receiving dual-polarized antenna network with the energy harvesting module, size is 21.5×4.5 cm. The printed slot antenna is vertically polarized. The printed dipole is horizontally polarized. The resonant frequency of the dipole with CSRR is around 0.33 GHz, which is lower by 15% than the resonant frequency of the printed dipole without CSRR. The measured antenna bandwidth is around 45% for S11 lower than -6 dB. The measured directivity and gain of the antenna with CSRR are around 5.5 dBi. The S11 of the optimized receiving metamaterial antenna is lower than -6 dB in the frequency range from 0.18 to 0.4 GHz, around 60% bandwidth. The receiving active sensor gain with TAV541 LNA is 12 ± 3 dB, and the noise figure is better than 1 dB, for frequencies from 0.1 to 1GHz.

The active computed and measured transmitting antenna gain with HPA VNA25, is 13 ± 3 dB 1 for frequencies from 0.1 to 0.8 GHz. The transmitting sensor output power is around 19.5 dBm.

Electromagnetic power amount in public centers, stadiums, hospitals, and malls may range from 1 μW/cm² to 5 mW/cm². The harvesting system efficiency increases as function of the RF power collected by the harvesting system. The efficiency of the harvesting system is around 50% for 0 dBm input power. However, the efficiency of the harvesting system is around 60% for 10 dBm input power.

The antennas and sensors presented in this chapter may be used in medical devices that improve the daily health of patients. Wearable antennas and healthcare devices are an important choice for healthcare organizations, hospitals, and patients. The wearable sensors presented in this chapter support the development of personal healthcare systems with online immediate medical staff responses to treat and improve patients’ health.

Basil M. Al Hadithi

Chapters authored

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