Topic 4, radio systems
After studying single microwave
components, such as transmission lines, impedance matching networks and
analysis of passive and active microwave networks, in this topic we
arrange those components to perform as complete radio systems.
Especially, we concentrate on microwave communication systems.
Other typical radio systems would include radars, transponders and
sensors but they are handled more in other courses. A crucial part of
radio systems is the antenna which is a component that in
transmission converts a guided wave coming from the transmission line
into a free-space spherical wave and in reception vice versa. The power
density (unit W/m2) of a spherical wave obey the inverse-square law 1/r2.
We assume that our students master the basic concepts and parameters of
antennas, such as far-field region, radiation/directional pattern,
directivity, gain, efficiency, effective aperture etc. In this topic, we
will first discuss transmitter and receiver architectures, especially mixers and superheterodyne receivers. One specific concern in all radio systems is noise
which deteriorates the quality of any radio link. A fundamental source
of noise is thermal vibrations in any material in a temperature above 0
K. All radio systems receive noise by the antenna (external noise from
nature, space and man-made devices) and generate additional noise in all
passive and active components inside the system. Noise defines the
minimum acceptable level of received signal when a particular radio
system can still reliably detect the signal. Very important concepts
studied in this topic are: equivalent noise temperature, antenna noise temperature, noise figure, noise bandwidth, signal-to-noise ratio (SNR), and link margin. We will also learn some methods how to manage with noise.
This part of the course addresses the following learning outcomes:
- The student is able to explain the operational principles of basic microwave systems, such as mixing phenomenon and superheterodyne transceivers.
- He/she can also calculate the relevant radio system parameters, such as signal-to-noise ratio, equivalent noise temperature, noise figure and link budget analytically.
- 10.1 Noise in microwave circuits
- 10.2 Noise figure
- 13.5 Mixers (Mixer characterics only)
- 14.1 System aspects of antennas
- 14.2 Wireless communication
Interactive lectures take place on Thu Feb 24 and Mar 3 at 9
- FileIn-class task FilePDF document
- FileIn-class task FilePDF document
Preliminary tasks
Return exercises
- FileExercise problems of Topic 4 FilePDF document
This is a supplement return box of exercise answers. Do NOT submit your answers here unless requested by a teacher. In order to get points, all exercise answers must be presented to a teacher during Monday exercise sessions.