Preface

Chapter 7 **3D Holographic Millimeter-Wave Imaging for Concealed Metallic Forging Objects Detection 125**

**Section 4 Microwave Heating and Drying Technologies 141**

Chapter 8 **Microwave Technology in Freeze-Drying Process 143**

Chapter 9 **Microwave-Assisted Green Extraction Technology for**

Chapter 10 **From Field to Shelf: How Microwave-Assisted Extraction**

Roberto Rosa, Erika Ferrari and Paolo Veronesi

**Techniques Foster an Integrated Green Approach 179**

**Sustainable Food Processing 159**

Lulu Wang

**VI** Contents

Mohsen Kalantari

Ruhan Askin Uzel

This book is a self-contained collection of scholarly papers targeting audiences of practicing researchers, academics, postgraduate students, and other scientists whose works are related to microwave technologies. This book intends to provide readers with a comprehensive overview of the current state of the art in microwave technologies. This book is divided into 10 chapters. Chapter 1 is a general introduction that elucidates the principles of microwave and some of the microwave applications. Chapters 2 to 10 are written by several authors. These authors are researchers, scientists, and experts in specific research fields, which are related to microwave engineering. The editor would like to take this opportunity to thank all the authors for their valuable book chapter contribution. In fact, each chapter provides introduction on the specific microwave technology as well as detailed explanation of the methodology on how to solve the raised issues, which include both academic and industry aspects.

Chapters 2, 3, and 4 focus on the analytical models for fractal array antenna design, analyti‐ cal models of microwave resonance system for high-frequency material characterizations, and simulation modeling for biomedical devices and electromagnetic interference (EMI) measurement setup. Analytical analysis has played a very important role in the academic microwave engineering and industries. Engineers in microwave field will be able to under‐ stand the operating background of the microwave systems or devices through analytical analysis easily, as it is the fundamental knowledge in microwave system designs before en‐ tering into further application. Based on the analytical models, the time spent on microwave system (antennas, sensors, etc.) designs and measurement setup can be shortened.

Chapters 5, 6 and 7 include emerging microwave instruments and devices. Chapter 5 presents a potential of microwave energy for energy-efficient lighting application using elec‐ trodeless sulfur lamp. The electrodeless sulfur lamps with microwave excitation are durable and economical, and they can achieve photosynthetically active radiation (PAR) up to 70% to 80%, which is suitable for larger greenhouse complexes. Chapter 6 presents numerous examples of microwave passive devices made by 3D printing with metal plating. Recently, 3D printing integrated with computer-aided design (CAD) is able to provide relative high precision and rapid and significant cost saving (human resources and material cost) for mi‐ crowave device fabrication compared to the traditional machining. Chapter 7 presents the microwave imaging system for the concealed metallic forging object detection. The micro‐ wave imaging system is made up of Vivaldi antenna array (as sensors) and 3D holographic millimeter-wave algorithm (inverse scattering). In fact, microwave imaging has higher sensi‐ tivity with respect to metallic materials, which provides a high contrast of electrical proper‐ ties between metallic and nonmetallic materials.

#### XII Preface

Chapters 8, 9, and 10 cover the microwave heating/drying and extraction technologies. Re‐ cently, most of the industrial sectors have been using microwave energy in drying or heat‐ ing process for their products; it is due to the microwave energy, which does not change the structure, color, and nature of the product after the heating/drying process. Furthermore, the cost of the used energy can be saved and easily controlled as well as the heating time.

> **Kok Yeow You** Universiti Teknologi, Malaysia

**Section 1**

**Review of Microwave Applications**

**Review of Microwave Applications**

Chapters 8, 9, and 10 cover the microwave heating/drying and extraction technologies. Re‐ cently, most of the industrial sectors have been using microwave energy in drying or heat‐ ing process for their products; it is due to the microwave energy, which does not change the structure, color, and nature of the product after the heating/drying process. Furthermore, the cost of the used energy can be saved and easily controlled as well as the heating time.

VIII Preface

**Kok Yeow You**

Universiti Teknologi, Malaysia

**Chapter 1**

**Provisional chapter**

**Introductory Chapter: RF/Microwave Applications**

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

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

**Introductory Chapter: RF/Microwave Applications**

DOI: 10.5772/intechopen.73574

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

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

Additional information is available at the end of the chapter

and author's experience in microwave researches.

Additional information is available at the end of the chapter

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

Kok Yeow You

**1. Introduction**

2.45 GHz.

Kok Yeow You

**Provisional chapter**
