**1. Introduction**

Compact size printed multiband monopoles are of interest for a variety of applications such as WLAN, RFID and mobile terminals. If the antennas can be fabricated with a planar structure using PCB techniques, the cost can be kept low and the fabrication process is greatly simplified.

It is well-known that the size reduction will decrease the radiation efficiency of the antenna especially when its size is very small compared to the free space wavelength at its lowest resonant frequency. Conventional high permittivity substrates can be employed to reduce the size of the microstrip antenna (e.g. printed microstrip patch) but raises other design issues. When using this approach the bandwidth of the antenna is decreased and the surface wave propagations are excited, which can lead to the scan blindness if a beam-steerable phased array is built based on this antenna element. Therefore, it is important to investi‐ gate techniques for the design of compact and low cost microstrip antennas with promis‐ ing radiation characteristics.

This chapter discusses various techniques of designing low cost, small-size printed monopole antennas and it is organized as follows. In section 2, antenna miniaturization techniques, based on fractal geometries and the use of lumped elements into the radiating element are discussed. In section 3, a low cost multiband printed planar monopole for mobile terminals is presented. This printed monopole exhibits five resonant frequencies and covers the desired frequency bands for mobile, WiMax and WLAN operations. Then in section 4, the design of a small size printed monopole array is addressed and two examples are given, one of which can be employed to increase the gain of the antenna and the other is suitable for MIMO applications of portable devices. Finally, recent developments in the field of low cost compact printed monopoles and arrays are discussed in section 5.

© 2014 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, and reproduction in any medium, provided the original work is properly cited.
