Radio frequency (RF) power amplifiers are used in everyday life for many applica-
tions including cellular phones, magnetic resonance imaging, semiconductor wafer
processing for chip manufacturing, etc. Therefore, the design and performance of
RF amplifiers carry great importance for the proper functionality of these devices.
Furthermore, several industrial and military applications require low-profile yet
high-powered and efficient power amplifiers.
With the rapid expansion of wireless consumer products,there has been a con-
siderable increase in the need for radio-frequency (RF) planning, link plan-
ning, and propagation modeling.A network designer with no RF background
may find himself/herself designing a wireless network. A wide array of RF
planning software packages can provide some support, but there is no substi-
tute for a fundamental understanding of the propagation process and the lim-
itations of the models employed. Blind use of computer-aided design (CAD)
programs with no understanding of the physical fundamentals underlying the
process can be a recipe for disaster. Having witnessed the results of this
approach, I hope to spare others this frustration.
The unguided transmission of information using electromagnetic waves
at radio frequency (RF) is often referred to as wireless communications,
the first demonstration of which took place at the end of the 19th cen-
tury and is attributed to Hertz. The technology was, shortly thereafter,
commercialised by, amongst others, Marconi in one of the first wire-
less communication systems, i.e., wireless telegraphy. In the first half of
the 20th century the technology was developed further to enable more
than the mere transmission of Morse code. This first resulted in uni-
directional radio broadcasting and several years later also in television
broadcasting.
The market for cellular phones and wireless data transmission equipment has changed
dramatically since the late 1970s when cellular phones were first introduced and the
late 1980s when wireless data equipment became available. As would be expected,
duringthistime RF test requirements and RF test equipment has changed dramatically.
