Transcript Case Study: C/Ku Band Earthstation Antennas

Overview of Electrical
Engineering
Lecture 8A:
Introduction to Engineering
1
Foundations of Electrical
Engineering
Electrophysics
 Information
(Communications) Theory
 Digital Logic

2
Lecture 1
Foundations of Electrical
Engineering

Electrophysics:
 Fundamental
theories of physics and
important special cases.
 Phenomenological/behavioral models for
situations where the rigorous physical theories
are too difficult to apply.
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Lecture 1
Hierarchy of Physics Theories Involved
in the Study of Electrical Engineering

Quantum electrodynamics
 Quantum
mechanics
 Schrödinger
 Classical
equation
electromagnetics
 Electrostatics
 Electrodynamics
 Circuit
theory
 Geometric optics
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Lecture 1
Maxwell’s Equations
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Lecture 1
Information Theory



Originally developed by Claude Shannon of Bell
Labs in the 1940s.
Information is defined as a symbol that is
uncertain at the receiver.
The fundamental quantity in information theory
is channel capacity – the maximum rate that
information can be exchanged between a
transmitter and a receiver.
The material in this slide and the next has been adapted from material from
www.lucent.com/minds/infotheory.
Lecture 1
6
Information Theory

Defines relationships between elements of
a communications system. For example,
 Power
at the signal source
 Bandwidth of the system
 Noise
 Interference

Mathematically describes the principals of
data compression.
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Lecture 1
Exercise: What is Information?

Message with redundancy:
 “Many

students are likely to fail that exam.”
Message coded with less redundancy:
 “Mny
stdnts are lkly to fail tht exm.”
Claude Shannon, founder
of Information Theory
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Lecture 1
Digital Logic
Based on logic gates, truth tables, and
combinational and sequential logic circuit
design
 Uses Boolean algebra and Karnaugh maps
to develop
minimized
logic circuits.

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Lecture 1
EE Subdisciplines
Power Systems
 Electromagnetics
 Solid State
 Communication/Signal Processing
 Controls
 Analog/Digital Design

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Lecture 1
Power Systems
Generation of electrical energy
 Storage of electrical energy
 Distribution of electrical energy
 Rotating machinery-generators, motors

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Lecture 1
Electromagnetics
Propagation of electromagnetic energy
 Antennas
 Very high frequency signals
 Fiber optics
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Lecture 1
Solid State
Devices
 Transistors
 Diodes (LED’s, Laser diodes)
 Photodetectors
 Miniaturization of electrical devices
 Integration of many devices on a single
chip

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Lecture 1
Communications/Signal Proc.
Transmission of information electrically
and optically
 Modification of signals
 enhancement
 compression
 noise reduction
 filtering

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Lecture 1
Controls
Changing system inputs to obtain desired
outputs
 Feedback
 Stability
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Lecture 1
Digital Design



Digital (ones and zeros) signals and hardware
Computer architectures
Embedded computer systems
 Microprocessors
 Microcontrollers
 DSP chips
 Programmable logic devices (PLDs)
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Lecture 1
Case Study: C/Ku Band Earthstation Antennas
Simulsat
Parabolic
Multiple horn feeds
Horn feed
ATCi Corporate Headquarters
450 North McKemy
Chandler, AZ 85226 USA
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Lecture 1
Case Study: C/Ku Band Earthstation Antennas
Incoming plane wave is
focused by reflector at
location of horn feed.
Geometric
Optics
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Lecture 1
Case Study: C/Ku Band Earthstation Antennas
Feed horn is
designed so that it
will illuminate the
reflector in such a
way as to maximize
the aperture
efficiency.
Maxwell’s
equations
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Lecture 1
Case Study: C/Ku Band Earthstation Antennas
Feed horn needs to
be able to receive
orthogonal linear
polarizations (V-pol
and H-pol) and
maintain adequate
isolation between the
two channels.
V-pol
H-pol
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Lecture 1
Case Study: C/Ku Band Earthstation Antennas
A planar orthomode
transducer (OMT) is
used to achieve good
isolation between
orthogonal linear
polarizations.
Maxwell’s Equations
(“Full-Wave
Solution”)
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Lecture 1
Case Study: C/Ku Band Earthstation Antennas
To LNB
Feed waveguide
(WR 229)
Maxwell’s
equations
Horn
Stripline circuit with OMT,
ratrace and WR229 transitions
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Lecture 1
Case Study: C/Ku Band Earthstation Antennas
Layout of the stripline trace layer
Single-ended probe
WR229
Transitions
Circuit
Theory
Differential-pair probes
Ratrace hybrid
50 ohm transmission line
Vias
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Lecture 1
Case Study: C/Ku Band Earthstation Antennas
The two linear
polarizations each
are fed to a LNB
(low noise block).
LNB
LNB
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Lecture 1
Case Study: C/Ku Band Earthstation Antennas
LNB:
LNA
Mixer
BPF
IF Output:
950-1750 MHz
(To Receiver)
Circuit
Theory,
Behavioral
Models,
Information
Theory
Local
Oscillator
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Lecture 1