Bui Cao Ninh - postgraduate student of Department of Radiophysics, Antennas and Microwave Technique of Moscow Aviation Institute. E-mail: buicaoninh@gmail.com

The development of mobile telephony is the expansion of used frequencies. The popularity of mobile communication systems has increased remarkably during the last decade and the market demand still continues to increase. As a fundamental part of these systems, antenna is one of the most important design issues in modern mobile communication units. Antennas are dependent on frequency, which are designed to operate for certain frequency bands. The rapid growth of mobile communication systems has forced to the use of novel antennas for base and mobile station applications (mobile phone, notebook computer, personal digital assistants (PDA), etc.). Earlier, mobile systems were designed to operate for one of the frequency bands of 2G (second generation) systems, which are Digital Cellular System (DCS), Personal Communications Service (PCS) and Global System for Mobile Communications (GSM). Nowaday, many mobile communication systems use several frequency bands such as GSM 900/1800/1900 bands (890-960 MHz and 1710-1990 MHz); Universal Mobile Telecommunication Systems (UMTS) and UMTS 3G expansion bands (1885-2200 MHz and 2500-2690 MHz); and Wireless Fidelity (Wi-Fi) / Wireless Local Area Networks (WLAN) bands (2400-2484 MHz and 5150-5825 MHz). Currently, there are types of antennas, they answer many of the requirements and are used in the wireless communication. Microstrip antennas, whip antennas occupy large group, subsequently modified in spiral antennas to minimize size, but with preservation of the electrical length, antennas of inverse types: Inverted L-antenna (ILA), Inverted F-antenna (IFA), Planar Inverted F-antenna (PIFA), low profile antennas and chip antennas. Generally, a single antenna can-t operate at all of these frequency bands of mobile communication, so multiple different antennas covering these bands separately should be used. However, usage of many antennas is usually limited by the volume and cost of the applications. Therefore, multiband and wideband antennas are essential to provide multifunctional operations for mobile communication. Today, the most popular designs are multiform PIFA (low profile antennas), including integrated microstrip and dielectric resonant antennas. In my work multiband and wideband antennas are expected to consider and find the best options.