**2. Microstrip antennas: types, applications, and design methodology**

### **2.1 Types and applications**

Since the concept of microstrip radiators was introduced by Deschamps in 1953, microstrip antennas only were manufactured in the 1970s with the use of the printed circuit technology (PCB) by Byron, Munson, and Howell [13–16]. Since then, microstrip antennas have been a subject of extensive research and development for military and commercial applications.

The most common type of microstrip antenna is the so-called patch antenna, which is fabricated with PCB technology by etching the shape of radiating patch above a dielectric substrate backed by a ground plane. Conventional patch shapes that result in narrowband and wide-beam antenna include square, rectangular, circular, and elliptical. Patch antennas have a low profile and can be mechanically robust and shaped to conform to the curving surfaces or embedded into portable terminals.

From the initial concept introduced in [13], a variety of MSA has been proposed to meet the operating requirements in modern wireless applications. **Figure 1** illustrates some examples of these antennas fabricated using PCB technology for different types of excitation: microstrip, CPW, coupled, and coaxial.

The operating bandwidth of an antenna is an initial design specification of paramount importance to the antenna designer. The frequency bands defined for some

**151**

[6–10].

**Table 1.**

**Figure 1.**

*Fractal and Polar Microstrip Antennas and Arrays for Wireless Communications*

wireless applications are shown in **Table 1**. Conventional patch antennas suffer with narrow impedance bandwidth, low gain, and low power handling capability [6]. However, patch antennas have been applied for portable devices and base stations. A challenge for the designer is to enhance the patch antenna impedance bandwidth without compromising its radiation properties. A variety of broadband techniques

The microstrip antennas (IFA, Inverted-F Antenna, and PIFA, Planar Inverted-F Antenna) are widely used in wireless communication terminals [2–4]. Printed monopole antennas are very popular in ultra-wideband applications [3]. Discrete patch or monopole radiators can be arranged in versatile arrays to improve bandwidth and directivity or to synthesize a given radiation pattern

for patch antennas can be found in the literature [3, 4, 9].

*Frequency bands of wireless communication services.*

*DOI: http://dx.doi.org/10.5772/intechopen.83401*

*Antennas manufactured using the PCB technology.*

*Fractal and Polar Microstrip Antennas and Arrays for Wireless Communications DOI: http://dx.doi.org/10.5772/intechopen.83401*

### **Figure 1.**

*Wireless Mesh Networks - Security, Architectures and Protocols*

for antenna designers to take into account.

**2.1 Types and applications**

ment for military and commercial applications.

information and communication technology permeate the society and are increasingly important to their development [3, 4]. Modern wireless applications demand esthetic, multifunctional, portable terminals (laptops and smartphones) that operate in multiple frequency bands and can integrate different wireless services: 4G, Wi-Fi, Bluetooth, NFC, GPS, etc. Future trends toward 5G systems also require enhanced mobile broadband for emergent applications, as wireless sensors network [5].

With the rapid advance of wireless communication systems, the use of antennas in base stations and portable terminals must meet increasingly stringent criteria, such as miniaturization, integration with other systems, and multiband or broadband operation [1–4]. Due to its attractive features, low-profile microstrip antennas (MSA) and arrays are well suitable to meet the demands of fixed or mobile wireless applications [6–10]. Antenna parameter specifications change according to application. Indeed, fixed

A trend in the application of antennas for modern wireless systems is the use of compact antennas with stable radiation coverage over a wideband [2–4]. An antenna must be compact in many situations: embedded antennas, wearable antennas, camouflaged antennas, etc. However, most often an antenna electrically small narrows the impedance bandwidth, reduces gain, and limits control of the resulting radiation pattern [6, 10]. This chapter discusses the design of innovative microstrip antennas with fractal and polar shapes, which has been optimized for wireless sensors network applications. To show the advantages and disadvantages of proposed antennas, their resonant and radiation properties are compared with that presented by conventional MSAs. The antenna types addressed include patches and printed monopoles. Further developments include microstrip feeding techniques, dielectric resonator

antennas must have high gain, stable radiation pattern, and bandwidth tolerance; embedded antennas should be efficient in radiation and possess larger beam width [3]. In short-range UWB wireless systems, the antenna bandwidth exceeds the lesser of 500 MHz or 20% of the center frequency [11, 12]. Thus, impedance bandwidth, gain, radiation pattern, and polarization are fundamental parameters

antenna (DRA), esthetic wearable antennas, and antenna arrays.

**2. Microstrip antennas: types, applications, and design methodology**

Since the concept of microstrip radiators was introduced by Deschamps in 1953, microstrip antennas only were manufactured in the 1970s with the use of the printed circuit technology (PCB) by Byron, Munson, and Howell [13–16]. Since then, microstrip antennas have been a subject of extensive research and develop-

The most common type of microstrip antenna is the so-called patch antenna, which is fabricated with PCB technology by etching the shape of radiating patch above a dielectric substrate backed by a ground plane. Conventional patch shapes that result in narrowband and wide-beam antenna include square, rectangular, circular, and elliptical. Patch antennas have a low profile and can be mechanically robust and shaped to conform to the curving surfaces or embedded into portable terminals.

From the initial concept introduced in [13], a variety of MSA has been proposed

The operating bandwidth of an antenna is an initial design specification of paramount importance to the antenna designer. The frequency bands defined for some

to meet the operating requirements in modern wireless applications. **Figure 1** illustrates some examples of these antennas fabricated using PCB technology for

different types of excitation: microstrip, CPW, coupled, and coaxial.

**150**

*Antennas manufactured using the PCB technology.*


### **Table 1.**

*Frequency bands of wireless communication services.*

wireless applications are shown in **Table 1**. Conventional patch antennas suffer with narrow impedance bandwidth, low gain, and low power handling capability [6]. However, patch antennas have been applied for portable devices and base stations. A challenge for the designer is to enhance the patch antenna impedance bandwidth without compromising its radiation properties. A variety of broadband techniques for patch antennas can be found in the literature [3, 4, 9].

The microstrip antennas (IFA, Inverted-F Antenna, and PIFA, Planar Inverted-F Antenna) are widely used in wireless communication terminals [2–4]. Printed monopole antennas are very popular in ultra-wideband applications [3]. Discrete patch or monopole radiators can be arranged in versatile arrays to improve bandwidth and directivity or to synthesize a given radiation pattern [6–10].

Fractal antennas have a natural multiband behavior and compact design and can be used as a reconfigurable microstrip antenna [17–19]. Optimized fractal antennas in size and performance are suitable for wireless applications [20]. Currently, fractal antennas have several commercial applications, and international companies such as Fractal Antenna Systems, Fractus, Rayspan, and Ficosa International, among others, explore the unique properties of fractals for the manufacture of commercial antennas. Recently, polar shape commercial antennas inspired by the Gielis formula have also been proposed [21].
