E&M/Communications Applications

E&M/Communications Applications

Aly E Fathy

Outline

• The microwave band

• Non-communication applications

• Communication Applications

• Breakthroughs

• Various Areas of Research at UT and other Research Centers

• Courses

Microwaves

Long waves

30-300 kHz

10-1 km

Medium waves (MW)

300-3000 kHz

1000-100 m

Short waves (SW)

3-30 MHz

100-10 m

Very high frequency (VHF) waves

Microwaves

30-300 MHz 0.3-30 GHz*

10-1 m 100-1 cm

Millimeter waves

30-300 GHz

10-1 mm

Submillimeter waves

300-3000 GHz

1-0.1 mm

Frequency

Wavelength

Infrared (including far-infrared)

300-416,000 GHz

104-0.72 m

* 1 GHz = 1 gigahertz = 10 Hertz or cycles per second,+ 1 m = 10-6 m.

Industrial Microwave Furnace

Waveguide

Mold Core

Mold

Inert Environment

Insulation

Crucible

Modular Unit

Non-Communication Application

Attenuation of the Atmosphere at Various Wavelengths

204060

Free Space Communication

Why Microwaves

Radio equipments are classified under VHF, UHF & Microwaves.

VHF and UHF radios used when few circuits are needed and narrow bandwidth.

Earlier equipments were large in size and use Analog Technology.

Recently Digital Radio with better efficiency is being used.

A Century of Antennas-- from Hertz to Hand-Held

Very large array of 27 steerable parabolic dish Antennas25 meter diameter, operating at ~ cm wavelengthTo listen to signals transmitted billions of year away

24 GPS Antennas, medium earth orbits-MEOOperating at 20 cm wavelengthUses helix antennas, at 20,000 km

Hand-held cell-phonesOperating at 30 cm wavelength

Microwave Use• Lower bands are already occupied

• Now we have better electronics, and modulation schemes

Advantages of Microwave Utilization:

• Antennas are more directive—better beam control.

• Wider operating bandwidth.

• Smaller size elements

Microwave Systems

Microwave communication is line of sight radio communicationFor directive antennas, or broadcasting with omi-directional antennas

Radio Transmission: the speech signals are converted to EMPower is transmitted in space towards destinationEM waves are intercepted by receiving antennas and signal power is collected

Types of Antennas

Antennas used can be:• Omni-directional-in this case radio power is transmitted Uniformly in all directionsSuch type of antenna are preferred where uniform coverage is desired such as in cellular systems.

• Directional: in case of UHF communication.

• Highly directional: in case of microwave communications, microwave signals are transmitted in very narrow beam.

Normally 3 M Diameter Antenna at 2 GHz BW has half power of about 3.4 degrees beam width.

Coverage

Radio Communications

Radio Communication is in use since early 30’s.

First was used for broadcasting then commercial communication.

Radio used for long distance telephone service.

Many phone lines are connected to anExchange, and many exchanges to a tower

Applications:

Cellular Communication

For providing cellular communication a number of antennas at a particular height are installed around a circular platform

DBS Antennas

DBS-History

Current Solutions for US DBS

Reflector Antennas for Stationary Reception

Low Profile Reflector Antennas

Complete Mechanical Steering

Low Fabrication Cost. ~12 inch

CO

ST

Mobility

Broadside Patch Array Antennas

Complete Mechanical Steering

High Fabrication Cost. >12inch

Phased Array Antennas ~6inch

Proposed Solution

Complete Mechanical Steering with limited range (due to beam tilt)

SIW, Low Fabrication Cost

Directivity

Efficiency

Research Progress

13 Elements Slotted Waveguide

13 x 6 elements Sub-Array

13 x 48 Elements Full

Array

12 Elements Slotted SIW Array

12x16 Elem

ents SIW

Sub-A

rray

12*64 Elements Slotted SIW Full Array

13x32 Elements SIW Array With Folded Feed Network

Antennas for Mobile Systems

Why Do we need Reconfigurable

Antennas?• Limited Space, and Volume

• Trend to further miniaturization

Difficulty to attain Directivity

G=4A/2, G = -18.5 dB/cm2 @1 GHz

(you add 3dB when you double the Area)

(you add 6 dB when you double the Frequency)

•Strong Antenna Interference due to Proximity

• More Services means more antennas

• Many are not used in same time.

Very Compact

TinyMulti-function

Does it all

Antenna Alternatives for Multi-Radio Application

Radio 1

Radio 2

Radio 3

Radio n

Ant.

Gain

Frequency

Ant.

Gain

Frequency

Broad Band AntennaBroad Band Antenna

Ant.

Gain

Frequency

Multi-Band AntennaMulti-Band AntennaReconfigurable AntennaReconfigurable Antenna

• Covers all bands of interest, Good for sim-ops • Higher Noise , Non Uniformity in Ant. Gain

Multiple Radios

• Covers few bands of interest, OOB noise supp. • Poor iso. between radios, stringent filter spec.

• Very good noise immunity, high Flexibility

• Requires switches, Poor for true sim-ops

Mini-Nested Patches

Reconfigurable Multiband

1st Band GSM850/900

2nd BandDCS/PCS/IMT2000

1st Band 802.11b/g/n

2nd Band

802.11a

Research Progress

“Maze” Reconfigurable Fractal Loop Antenna

MEMS

SwitchesDC

Feeds

RF blocking resistor

Switch Locations

50cm coaxial cable

42mm

11mm

Ground

90mm

10mm

p-i-n diodes

50cm coaxial cable

“mini-Maze” Reconfigurable Bent Monopole Antenna with MEMS switch

Reconfigurable Multi-band branched Monopole Antenna

Reconfigurable Multi-band Twin PIFA Antenna with PIN diode switch

Power Amplifiers and Combiners

THz- BACKGROUND

• The detection of concealed weapons and explosives represents one of the most daunting problems facing the military and civilian law enforcement personnel.

• The exposure and identification of biological and chemical weapons is

also a major homeland security concern.

• Terahertz (THz) imaging, by virtue of its ability to penetrate materials and its short wavelength (leading to high resolution), and THz spectroscopy, due to its capability to recognize unique signatures of dangerous biological and chemical agents, provide the most promising approach to address these problems.

Homeland Security Applications

Potential Security Applications

Detection of hidden weapons and explosives

Detecting non-metallic weapons

Postal screening of envelopes for bacteria

Chem/bio detection

Security screening wand

Explosives

Stand-off detection

Postal screening

Envelope

Terahertz Images Can Reveal Objects Concealed Under Cloth, Paper, Tape, Even Behind Walls

Objects Concealed Under clothes Knife Wrapped in Newspaper

29

See Through Prototype System

Universal Automation Mechanism: Developed in MatlabUtilized GPIB bus and parallel port protocol

Dental

Powerful Medical Imaging Capabilities of THz

Brain

White light image THz image

THz device and probe (TeraView)

Skin CancerNormal skin

Diseasedskin

CONFORMAL ANTENNAS

…Fast Computations, New Materials…

• New Exotic Materials have been recently developed.• Stealth Technology and Many others can benefit

E-Textiles

Courses Offered at UT

Fields Antennas and Propagation

Microwave circuits EMC

Electromagnetic Fields I Electromagnetic Fields II

Phased Array Antennas I Phased Array Antennas II

Wireless Communications

Holographic Antenna Features

• True re-configurable aperture, NOT simple switching.

• The surface wave provides relatively low loss RF distribution channels

• Phased array performance without phased array feed complexity or cost

• Highly compact package

Conductive Fringe Pattern Far-Field Pattern

Conductive Region (Yellow) Non-Conductive Region (Blue)Radar Scanned

Aim Point

Radar Azimuth (deg): 015Radar Elevation (deg): 000

Description of Scenario:

• Search Along Azimuth 0-30 Deg, 0 Deg Elevation • Array Turned ‘Off’ - Non-Conducting Surface• Search Along Azimuth 30 Deg to 0 Deg, 5 Deg

Elevation • Place Target Into Track, Then Lose Track• Switch to Wide Beam to Re-Acquire Target• Continue Target Track


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Mode: OFF


Mode: OFF


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Mode: Re-Acquire


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Date post:	31-Jan-2016
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E&M/Communications Applications

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