Chapter 1
Introduction
This chapter provides a short overview on widely used microwave and RF applications and the denomination of frequency bands. We will start out with an illustrative case on wave propagation which will introduce fundamental aspects of high frequency technology. Then we will give an overview of the content of the following chapters to facilitate easy orientation and quick navigation to selected issues.
1.1 Radiofrequency and Microwave Applications
Today, at home or on the move, every one of us uses devices that employ wireless technology to an increasing extent. Figure 1.1 shows a selection of wireless communication, navigation, identification and detection applications.
In the future we will see a growing progression of the trend of applying components and systems of high frequency technology to new areas of application. The development and maintenance of such systems requires an extensive knowledge of the high frequency behaviour of basic elements (e.g. resistors, capacitors, inductors, transmission lines, transistors), components (e.g. antennas), circuits (e.g. filters, amplifiers, mixers) including physical issues such as electromagnetic wave propagation.
High frequency technology has always been of major importance in the field of radio applications, recently though RF design methods have started to develop as a crucial factor with rapid digital circuits. Due to the increasing processing speed of digital circuits, high frequency signals occur which, in turn, create demand for RF design methods.
In addition, the high frequency technology's proximity to electromagnetic field theory overlaps with aspects of electromagnetic compatibility (EMC). Setups for conducted and radiated measurements, which are used in this context, are based on principles of high frequency technology. If devices do not comply with EMC limits in general a careful analysis of the circumstances will be required to achieve improvements. Often, high frequency issues play a major role here.
Table 1.1 shows a number of standard RF and microwave applications and their associated frequency bands [1–3]. The applications include terrestrial voice and data communication, that is cellular networks and wireless communication networks, as well as terrestrial and satellite based broadcasting systems. Wireless identification systems (RFID) within ISM bands enjoy increasing popularity among cargo traffic and logistics businesses. As for the field of navigation, GPS should be highlighted, which is already installed in numerous vehicles and mobile devices. Also in the automotive sector, radar systems are used to monitor the surrounding aresa or serve as sensors for driver assistance systems.
Table 1.1 Wireless applications and frequency ranges
| Cellular mobile telephony |
| GSM 900 | Global System for Mobile Communication | 880 … 960 MHz |
| GSM 1800 | Global System for Mobile Communication | 1.71 … 1.88 GHz |
| UMTS | Universal Mobile Telecommunications System | 1.92 … 2.17 GHz |
| Tetra | Trunked radio | 440 … 470 MHz |
| Wireless networks |
| WLAN | Wireless local area network | 2.45 GHz, 5 GHz |
| Bluetooth | Short range radio | 2.45 GHz |
| Navigation |
| GPS | Global Positioning System | 1.2 GHz, 1.575 GHz |
| Identification |
| RFID | Radio-Frequency Identification | 13.56 MHz, 868 MHz, |
| | 2.45 GHz, 5 GHz |
| Radio broadcasting |
| FM | Analog broadcast transmitter network | 87.5 … 108 MHz |
| DAB | Digital Audio Broadcasting | 223 … 230 MHz |
| DVB-T | Digital Video Broadcasting - Terrestrial | 470 … 790 MHz |
| DVB-S | Digital Video Broadcasting - Satellite | 10.7 … 12.75 GHz |
| Radar applications |
| SRR | Automotive short range radar | 24 GHz |
| ACC | Adaptive cruise control radar | 77 GHz |
1.2 Frequency Bands
For better orientation, the electromagnetic spectrum is divided into a number of frequency bands. Various naming conventions have been established in different parts of the world, which often are used in parallel. Table 1.2 shows a customary classification of the frequency range from 3 Hz to 300 GHz into eight frequency decades according to the recommendation of the International Telecommunications Union (ITU) [4].
Table 1.2 Frequency denomination according to ITU
| 3 … 30 kHz | VLF - Very Low Frequency |
| 30 … 300 kHz | LF - Low Frequency |
| 300 kHz … 3 MHz | MF - Medium Frequency |
| 3 … 30 MHz | HF - High Frequency |
| 30 … 300 MHz | VHF - Very High Frequency |
| 300 MHz … 3 GHz | UHF - Ultra High Frequency |
| 3 … 30 GHz | SHF - Super High Frequency |
| 30 … 300 GHz | EHF - Extremely High Frequency |
Figure 1.2a shows a commonly used designation of different frequency bands according to IEEE-...