**Introductory Chapter: RF/Microwave Applications**

**Introductory Chapter: RF/Microwave Applications**

DOI: 10.5772/intechopen.73574

#### Kok Yeow You Additional information is available at the end of the chapter

Kok Yeow You

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.73574

**1. Introduction**

Owing to the rapid development of microwave technology, the microwave components and devices are increasingly common and relative low price compared to 10 years ago. Nowadays, microwave devices are often used and become an indispensable necessity in our daily routines, such as microwave ovens, mobile phones, and Internet. This introductory chapter reviews the microwave applications in this era based on a detailed literature survey and author's experience in microwave researches.

Radio waves and microwaves are a form of electromagnetic radiation with operating frequencies ranging from 30 to 300 MHz and 300 MHz to 300 GHz, respectively [1]. Different microwave applications and technologies will use certain frequency band to avoid frequency interference. These frequencies are grouped into several smaller bands. The most commonly used frequency spectrum classification today is created by the Institute of Electrical and Electronics Engineers (IEEE), which is listed in **Table 1**. Microwave applications for heating and crushing normally use high microwave power which is up to megawatts. In contrast, low microwave power (less than milliwatts) is widely used for domestic wireless communication or high-frequency electronic devices. Microwave applications can be categorized into two groups, namely, communication and noncommunication. Industrial, scientific, and medical (ISM) applications are normally classified as noncommunication group. Several scopes of microwave applications are listed in **Table 2**. The first three industrial, scientific, and medical (ISM) frequency allocations (at 13.66 MHz, 27.32 MHz, and 40.98 MHz) were designated by US Federal Communications Commission (FCC) in 1945 [2]. Recently, there are two microwave frequencies allocated by the FCC for ISM usage, namely, 915 MHz and 2.45 GHz.

Currently, most of the applications are devoted to the 2.45 GHz point, since it provides a suitable compromise between power deposition and penetration depth. The ISM bands defined

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© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons


**Table 1.** Institute of Electrical and Electronics Engineers (IEEE) frequency spectrum.

by the International Telecommunication Union (ITU) are listed in **Table 3** [1]. However, during recent years, ISM bands have also been shared with license-free error-tolerant communications applications, such as wireless LANs. In addition, now is the era of the fourth industrial revolution, so-called Industry 4.0, which most operation systems in the industry are in cyber based. Hence, the combination between communication (Internet) and noncommunication (microwave things) technologies is increasingly popular in order to produce smart devices, so-called Internet of Things (IoT), in which the devices are embedded with electronics, software, sensors, actuators, and network connectivity that are capable of covering a variety of protocols, domains, and applications, which include the automotive industry, public safety, emergency services, and medical field [3].

Within the past 40 years, microwave technology using frequency operation exceeding 300 GHz to 3 THz also existed, so-called Terahertz technology. In fact, operating frequency of 300 GHz to 3 THz occupies a middle ground between microwaves and infrared light waves. The corresponding range of the wavelength for the Terahertz frequencies is 0.1–1 mm; thus, it is a denominated submillimeter wave [27]. The Terahertz technology is widely utilized in the field of astronomy, medical, and security, such as space-based remote

sensing and medical diagnostic imaging [28–31], due to the submillimeter waves that are nonionizing, and it can penetrate a wide variety of nonconducting materials. Recently, high operating frequency requirements for microwave test instruments are increasing, such as recent commercial vector network analyzer which is capable of achieving 1.1 THz. Hence, in future, these microwave components and devices are expected to be very small

**Table 2.** Microwave applications for communication and noncommunication technologies.

8 Radiation for agricultural pest control

intrusion of persons

**Communication [3–8] Noncommunication [9–26]**

1 Sensors for industrial, agricultural/food, and medical processing, such as moisture measurement, ripeness/storage period determination, fruit sweetness detection, control of milk of lime, monitoring of nitrogen/phosphorus content in fertilizer, medical diagnostic, moisture soil testing, metal crack detector, and storage

Introductory Chapter: RF/Microwave Applications http://dx.doi.org/10.5772/intechopen.73574 5

pasteurization) in food industry to control pathogenic and spoilage

3 Industrial heating applications, such as casting waxes, sintering ceramics/metal powders, melting of glass/rubber, metal coating,

4 Medical applications, such as hyperthermia treatments, bioimpedance instrumentation, and medical diagnostic imaging (to detect a location or movement of objects within a human body or

5 Material characterization fixtures (materials including graphene, metamaterials, carbon nanotube, conductive polymer, hightemperature superconductor, aerogel, ceramics, semiconductor, polymer insulation, fibers, gases, and chemical liquids)

6 Image scan systems to detect the images of buried objects, location of objects contained within a wall, location or movement of persons or objects which are located on the other side of a wall, as well as the

7 Civil engineering applications (rock crushing, tar road comminuting)

2 Heating/drying or freeze-drying process (sterilization /

tank measurement devices

microorganisms in packaged foods

brazing, and paper/wood drying

animal body)

1 Communication network systems, such as high-speed home and business networking devices (modem and router), device-to-device communication (D2D) system, massive MIMO technology, cloud technologies,

and small cell access points

analyzer

2 Communication devices and test instruments, such as spectrum analyzer, RF power meter, frequency counter, signal generator, and vector network

3 Navigation systems such as maritime navigation, Global Positioning System (GPS), air traffic control, airborne radars,

and satellite communication

4 Wireless remote control for security and healthcare systems such as automatic gate/door, automatic barrier systems, burglar alarms, and industrial automation systems (Industry 4.0)

5 Vehicular radar systems to detect the location and movement of objects near a vehicle, enabling features such as near collision avoidance, improved airbag activation, and suspension systems that better respond to road conditions

6 Entertainment and information communication devices/systems such as television broadcast, FM broadcast, radio beacons, maritime radio, walkietalkie, coast guard communication, satellite communication, and weather

7 Domestic communication devices, such as 4G/5G smart phone, computer, Bluetooth, Wi-Fi devices, wireless webcam, and wireless microphones

and sensitive.

radars


**Table 2.** Microwave applications for communication and noncommunication technologies.

by the International Telecommunication Union (ITU) are listed in **Table 3** [1]. However, during recent years, ISM bands have also been shared with license-free error-tolerant communications applications, such as wireless LANs. In addition, now is the era of the fourth industrial revolution, so-called Industry 4.0, which most operation systems in the industry are in cyber based. Hence, the combination between communication (Internet) and noncommunication (microwave things) technologies is increasingly popular in order to produce smart devices, so-called Internet of Things (IoT), in which the devices are embedded with electronics, software, sensors, actuators, and network connectivity that are capable of covering a variety of protocols, domains, and applications, which include the automotive industry, public safety,

**Millimeter waves Extremely high frequency (EHF) (30–300 GHz) (10–1 mm)**

**Table 1.** Institute of Electrical and Electronics Engineers (IEEE) frequency spectrum.

**Electromagnetic wave spectrum Frequency band Wavelength Radio waves Very high frequency (VHF) (30–300 MHz) 10–1 m Microwaves Ultrahigh frequency (UHF) (300–3000 MHz) (100–10 cm)**

4 Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing

P band (230 MHz–1 GHz) 130–30 cm L band (1–2 GHz) 30–15 cm S band (2–4 GHz) 15–7.5 cm **Super high frequency (SHF) (3–30 GHz) (10–1 cm)** S band (2–4 GHz) 15–7.5 cm C band (4–8 GHz) 7.5–3.75 cm X band (8–12.5 GHz) 3.75–2.4 cm Ku band (12.5–18 GHz) 2.4–1.67 cm K band (18–26.5 GHz) 1.67–1.13 cm Ka band (26.5–40 GHz) 1.13–0.75 cm

Ka band (26.5–40 GHz) 1.13–0.75 cm V band (40–75 GHz) 7.5–4 mm W band (75–110 GHz) 4–2.73 mm Millimeter band (110–300 GHz) 2.73–1 mm

Within the past 40 years, microwave technology using frequency operation exceeding 300 GHz to 3 THz also existed, so-called Terahertz technology. In fact, operating frequency of 300 GHz to 3 THz occupies a middle ground between microwaves and infrared light waves. The corresponding range of the wavelength for the Terahertz frequencies is 0.1–1 mm; thus, it is a denominated submillimeter wave [27]. The Terahertz technology is widely utilized in the field of astronomy, medical, and security, such as space-based remote

emergency services, and medical field [3].

sensing and medical diagnostic imaging [28–31], due to the submillimeter waves that are nonionizing, and it can penetrate a wide variety of nonconducting materials. Recently, high operating frequency requirements for microwave test instruments are increasing, such as recent commercial vector network analyzer which is capable of achieving 1.1 THz. Hence, in future, these microwave components and devices are expected to be very small and sensitive.


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s17051123

**119**:14-16

\* Subject to local acceptance

\*\*Only Europe, Africa, the Middle East/Middle West of the Persian Gulf, the former Soviet Union, and Mongolia \*\*\*Only Americas, Greenland, and some of the eastern Pacific Islands

**Table 3.**Industrial, scientific, and medical (ISM) operating frequency band defined by the International Telecommunication Union (ITU).
