Engr 1202 E01 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 – MHz Broadcast TV (old)- requires external antenna –Channels MHz –Channels MHz –Channels MHz –Channels MHz –Channels 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 MHz – Current frequency of operation of most mobile phones Bluetooth and Wi-Fi devices MHz (2.4 – GHz) GPS – and 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 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 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

PCS Band 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 Transmits at –2.4 GHz (802.11b and g) –5.0 GHz (802.11a) Transfer Rates –802.11a and g (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

GPS systems uses orbiting satellites The primary frequency of operation is MHz with a secondary frequency of 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 Project Research, design, and fabricate a miniature planar antenna for use in: 1)Mobile phone using the PCS frequency of MHz 2)“Bluetooth” and Wi-Fi antenna using the frequency band of MHz 3)RFID antenna using the frequency band of MHz 4)GPS antenna using the frequencies of MHz and 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:  (wavelength) m/cycle f (frequency) cycles/sec = hertz c (speed of light) m/sec  3.0 x 10 8 m/sec Wavelength equation  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 10 6 Hz = 8.50 x 10 8 Hz 2.Use wavelength equation = c/f where c = speed of light = 3.0 x 10 8 m/sec  x 10 8 m/sec ) / (8.50 x 10 8 cycles/sec)  =.353 m/cycle Convert to cm gives  = 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 10 8 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

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 DrawingDesign arrayed for 4” wafer

Assignment due next class HW #2 from the web site –Frequency and wavelength work sheet Sketch your antenna design to be ready to transfer into AutoCAD A final report on the project is due at completion. –PowerPoint format –One per team –Summary of project including photos in the clean room