Engr 1202 ECE
Clean Room Project
Dilbert the engineer gets
special recognition
September 2005
2014 Version – does not
even have my name!
AC vs. DC Circuits
DC and AC devices in everyday life
• DC Devices– Batteries
– Automotive electronics
– Portable electronics
• IPod
• Cellular Phone
• PDA
– Laptop computers
– Desktop computers
– Solar cells
– Computer and memory
chips
• AC Devices– Electric wall outlets
– Household appliances
– High voltage transmission
lines
– Electromagnetic
transmissions
• Mobile phone signals
• Satellite signals
• Radio signals
AC Frequency
• Number of complete cycles per unit time
• Units are hertz, Hz
• Units are cycles per second
• Household electrical outlets operate at 60
hertz or 60 cycles per second
• Electromagnetic waves operate at much
higher frequencies
Sun burn
Frequency Allocations
Broadcast Frequencies• Use of frequencies for broadcast are controlled by the Federal
Government – the FCC - Federal Communications Commission
• License required to use a given frequency
• Companies purchase licenses to use these frequencies
• Specific bands are setup for all transmissions
– Police/Fire/EMS radio
– Commercial aircraft
– Marine radios
– Mobile phones
– Military applications
– Citizen band radio
– GPS
– RFID
• Bluetooth and Wi-Fi operate in the scientific unlicensed band where products can be developed without a FCC license
Typical
large
broadcast
antenna
Very tall, often on mountains, to transmit over long distances
Some common frequencies• AM Radio
– 535 to 1605 KHz
• FM Radio
– 88-108 MHz
• Broadcast TV (old)- requires external antenna
– Channels 2-4 54-72 MHz
– Channels 5-6 76-88 MHz
– Channels 7-13 174-216 MHz
– Channels 14-36 470-608 MHz
– Channels 38-69 614-806 MHz
• Today, most TV transmissions are digitized and sent via cable, fiber optics, or satellite
Wireless Technology
• Wireless devices transmit information via
Electromagnetic waves
• Early wireless devices
– Radios – often called wireless in old WWII
movies
– Broadcast TV
– TV remote controls
– Garage door openers
Wireless technology
• Today’s wireless devices include
– Mobile phones
– Satellite TV
– Satellite radio
– Global Positioning Systems (GPS)
– “Bluetooth” devices
– Wi-Fi systems
– RFID tags
Wireless frequencies for the EE
project
• PCS digital phones - 1850-1990 MHz – Current frequency of operation of most mobile phones
• Bluetooth and Wi-Fi devices - 2400-2497 MHz (2.4 – 2.497 GHz)
• GPS – 1575.42 and 1227.60 MHz
• RFID – multiple frequencies – 860 to 960 MHz very common
Smart phones dominate cellular
systems today
Apple iPhone
A computer
that is also a
cell phone
Mobile Phone (Cellular) Systems
• Mobile phones are two-way radios. They transmit and receive RF signals. Old style phones are not radios.
• Original mobile phones used a single large central antenna and had limited channels available to carry signals. Only a small number of mobile phones were available in a city due to the limited amount of usable frequency bands.
• Cellular technology allowed for a near limitless number of mobile phones to operate in a city.
Early Mobile Phones where not cellular but used a common centrally located tall antenna (similar to police and fire radios) and were limited in the number of phone numbers available
Mobile Phone (Cellular) Systems
• Cellular systems operate at a frequency of 824 to 894 Mhz, and 1850 to 1990 Mhz . Other bands are also being used as demand increases.
• These frequency bands are controlled by the Federal government.
• The original cell phones operated at 824-894 MHz. Sometimes these phones are referred to as “analog phones” since digital technology had not yet been developed.
• Many systems today operate at 1850 to 1990 Mhz, the PCS band in the digital mode but can also operate at the lower frequency band. These phones are called “dual band” phones.
• The term “cellular” refers to the fact that service areas are divided into “cells” typically 1- 10 miles apart. Cell size is dependent on the population density of the area. Large population areas require closer spaced cells.
• Each cellular company has their own towers, thus the large number of towers throughout the area. Sometimes towers will have multiple sets for the same system or multiple systems.
My first cell phone - 1992
PCS Band
1850-1990
MHZ
Grid pattern for cellular antenna
Adjacent
grids do not
use the same
frequency
Mobile Phone (Cellular) Systems
• Each phone has a unique code.
• If your cell phone is “on”, it is transmitting a signal to the nearest cell tower.
• This signal locates you and allows you to receive calls.
• It also identifies your phone, carrier, and status of your account.
• When you make a call, it is transmitted to the nearest tower and it is then routed to the person you called.
• The call may go via radio waves, land lines, or satellite.
• As you move, the call can be transferred to the next cell. This is done automatically as signal strength changes
• Phones typically transmit with around 600mW of power.
Typical cellular system
antenna tower with two
sets of base station
modules
Base station RF
transmit/receive
modules
Large cell phone
antenna is a
remote location
Communities are trying to disguise
cellular towers
Several cell phone antenna towers like this
are near the campus
First cell phone tower on
campus
“ Bluetooth” • “Bluetooth” named after a Swedish King that
united the country. First proposed by Ericsson
• The systems utilizes an unregulated band of frequencies at 2.4 GHz that operate on a relatively short distance, about 10m.
• Bluetooth uses a “frequency hop transceiver” to handle device traffic. A radio channel is shared by a group of devices and is synchronized by one device known as the master. This forms a piconet.
• Bluetooth devices can be used to connect a headset to a cellular phone, a printer to a computer, a digital camera to a computer, etc.
• Because “Bluetooth” circuits are low power with low battery requirements, the chipsets are relatively inexpensive.
• Many newer devices have “Bluetooth” already built into them.
Wi-Fi –provides access to internet
wirelessly• Uses IEEE standard 802.11
• Transmits at – 2.4 GHz (802.11b and 802.11g)
– 5.0 GHz (802.11a)
• Transfer Rates– 802.11a and 802.11g (54 Megabits per second)
– 802.11b (11 Mega bits per second)
• Frequency hopping for security
• Range: about 100 meters (300 feet)
• Range limited by output power level.
• Often called a “Hotspot”
Installing a home Wi-Fi network is easy and cheap
A city wide Wi-Fi zone can be
created using multiple routers
similar to the cell phone
antenna network
“Bluetooth” vs. Wi-Fi
• Both use the 2.4 GHz frequency band
• Both could use the same antenna
• “Bluetooth” is for short range, about 10m
• Wi-Fi has a longer range, about 100m
• “Bluetooth” can operate from a small
battery
• Wi-Fi requires higher power, usually plugs
into a home electrical outlet
Smart phones can access the internet
either through a local Wi-Fi access
point or the cellphone network
Instead of using a
Wi-Fi location, you
can access the
internet through
the cellular phone
network BUT you
will pay for the
time. Could be
expensive unless
you have unlimited
data downloads Allows for your laptop to
access the internet via
the cellular system
RFID tags
• Passive -uses the incoming signal for
power to transmit
• Active- requires an internal power supply,
more expensive and less widely used
• Could replace bar codes and security
attachments on merchandise
• Implantable for medical and security data
Implantable RFID device
Companies like Wal-Mart plan
to use RFID extensively
RFID gate access at UNCC
RFID
Antenna
RFID chip
RFID chip added
GPS systems uses orbiting
satellites The primary frequency of
operation is 1575.42 MHz with a
secondary frequency of 1227.6
MHz
Cellular GPS systems use local
cellular antennas
Stationary Satellites Orbit the
Earth
GPS devices calculate the
signal time from each satellite
and using triangulation
determine location
Communications – the key to
technology progress• Data, voice, and video are all key
elements
• Both electrical and computer engineers
will play a key and vital role
• “Wireless” communications is the
dominate form
• The EE project will focus on
communications systems and a key
element of these system, the antenna.
What is an antenna
The antenna is an essential part of any
wireless communication system that
sends information over the air. An
antenna is a device that provides a
means for radiating or receiving
electromagnetic waves. It provides a
transition from a guided wave on a
transmission line to a free space wave or
vice versa.
Every communications device needs an
antenna
The Engr 1202 EE ProjectResearch, design, and fabricate a miniature planar antenna
for use in:
1) Mobile phone using the PCS frequency of 1850-1990
MHz
2) “Bluetooth” and Wi-Fi antenna using the frequency
band of 2400-2597 MHz
3) RFID antenna using the frequency band of 860-960
MHz
4) GPS antenna using the frequencies of 1227.60 MHz
and 1575.42 MHz
Maximum size of 20mm x 20mm, minimum size of 10mm x
10mm. Can be rectangular. Width on antenna not less
than 1mm. Design to have no sharp corners.
Cell phone showing internal
antenna
Antenna
Example of a miniature antenna for
a mobile phone/watch
Antenna Design
• In antenna design, an important design
parameter is the wavelength of the EM
wave
• Wavelength is a function of frequency
• Antenna length is typically either
1. 1 wavelength
2. ¼ wavelength
3. ½ wavelength
Frequency vs wavelength
Wavelength
Wavelength Calculations
• Wavelength units:
l (wavelength) m/cycle
f (frequency) cycles/sec = hertz
c (speed of light) m/sec = 3.0 x 108 m/sec
• Wavelength equation
l = c / f
m/cycle = (m/sec) / (cycles/sec)
Frequency must be converted to Hz
Sample calculation• Find the wavelength of a frequency of 850 MHz
1. Convert 850 MHz to Hz
850 MHz = 850 x 106 Hz = 8.50 x 108 Hz
2. Use wavelength equation
l= c/f where c = speed of light = 3.0 x 108 m/sec
3. l = (3.0 x 108 m/sec ) / (8.50 x 108 cycles/sec)
4. l = .353 m/cycle
Convert to cm gives
5. l = 35.3 cm/cycle
6. For a ¼ wavelength antenna =
(35.3cm/cycle)/4=8.825cm/cycle
To find wavelength
1. Convert frequency to Hz (cycles/sec)
2. Use 3.0 x 108 m/sec for speed of radio
waves (same as speed of light)
3. Use equation wavelength (m/cycle) =
speed of light (m/sec) / frequency
(cycles/sec)
Wavelength is use to determine antenna
length
Wireless frequencies for the EE
project
• PCS digital phones - 1850-1990 MHz – Current frequency of operation of most mobile phones
• Bluetooth and Wi-Fi devices - 2400-2497 MHz (2.4 – 2.497 GHz)
• GPS – 1575.42 and 1227.60 MHz
• RFID – multiple frequencies – 860 to 960 MHz very common
Antenna Design
• Design can take an artistic form (not the
best design for an antenna but OK for this
project)
• Design must not be controversial
– Not religious
– Not gang sign
– Not sexual
– Not offensive to any group
Example of antenna design
Dimension Drawing Design arrayed for 4” wafer
Example of antenna design
Dimension Drawing Design arrayed for 4” wafer
Example of antenna design
Dimension Drawing Design arrayed for 4” wafer
Example of antenna design
Dimension Drawing Design arrayed for 4” wafer
Example of antenna design
Dimension Drawing Design arrayed for 4” wafer
Assignment due next lecture
Frequency / wavelength
work sheet
After your visit to the clean room – complete
the team choice worksheet and submit
before the next clean room visit. This will
determine the application and length of your
antenna design