VSWR
Symbols
| Ae | effective antenna aperture | |
| c | speed of light | |
| D | directivity | |
| D = max[D(ϑ, ϕ)] | directivity function | |
| η | effciency | |
 |
unit vector along the r axis | |
 |
electric field in space frequency | |
| f | frequency | |
| G | gain | |
| G = max[G(ϑ, ϕ)] | gain function | |
| Γ | reflection coeffcient | |
| I p | input current antenna | |
| k | coverage factor | |
| L | length of the radiating aperture | |
| λ 0 | wavelength in free space | |
| Mv | measurement value | |
| Pin | input power | |
| Pt | total radiated power | |
| P(ϑ, ϕ) | normalized radiation power | |
| R | radial distance from the antenna | |
| Ra | resistive | |
| RL | radiated losses | |
| Rr | radiated resistance | |
| Rv | reference value | |
| μ sys | system uncertainty | |
 |
Poynting vector | |
| V p | input voltage antenna | |
| X a | reactance | |
| Z 0 | characteristic impedance | |
| Z a | input impedance | |
| Z g | generator impedance = Rg |
1 Introduction
Yueping Zhang
School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore
1.1 Background
As the technology of choice for integration of digital circuitry, a complementary metal oxide semiconductor (CMOS) was proposed for the integration of analog circuitry for radio frequency (RF) applications in the mid‐1980s, aiming for the ultimate goal of full integration of an entire wireless system on a chip [1]. In the mid‐1990s, the first fully integrated CMOS transceiver for data communications in the 900‐MHz industrial, scientific and medical (ISM) band was successfully demonstrated [2]. Since then, CMOS has been the enabler for wireless systems on chip (SoCs) operating from a few to tens of gigahertz. Figure 1.1 shows the die micrograph of the first wireless SoC, a 2.4‐GHz CMOS mixed RF analog–digital Bluetooth radio announced at the International Solid‐State Circuits Conference (ISSCC) 2001 [3]. The die size is 40.1 mm2. It integrates on the same substrate a low intermediate frequency (IF) receiver, a Cartesian transmitter, a baseband processer, an advanced reduced‐instruction set‐computer machine (ARM) processor, flash memory, and random‐access memory (RAM).
Full SoC integration is clearly not suitable in all cases. In fact, the radio chip is separate in many cases. Traditionally, silicon germanium (SiGe) seems to have been preferred to CMOS for analog RF. Figure 1.2 shows the die micrographs of the first SiGe 60‐GHz transmitter and receiver disclosed at ISSCC 2006 [4]. The die sizes are 4.0 × 1.6 mm2 and 3.4 × 1.7 mm2, respectively. The level of integration achieved in these chips was high then for 60‐GHz radios. The transmitter chip integrates a power amplifier, image‐reject driver, IF‐to‐RF up‐mixer, IF amplifiers, quadrature baseband‐to‐IF mixers, phase‐locked loop (PLL), and frequency tripler. The
