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

Frequency Wavelength l 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 Infrared (including far-infrared) 300-416,000 GHz 104-0.72mm * 1 GHz = 1 gigahertz = 10 Hertz or cycles per second, + 1 mm = 10-6 m. Microwaves

Waveguide Inert Environment Mold Core Mold Non-Communication Application Industrial Microwave Furnace Modular Unit Crucible Insulation

Free Space Communication Attenuation of the Atmosphere at Various Wavelengths 60 40 20

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 Antennas 25 meter diameter, operating at ~ cm wavelength To listen to signals transmitted billions of year away 24 GPS Antennas, medium earth orbits-MEO Operating at 20 cm wavelength Uses helix antennas, at 20,000 km Hand-held cell-phones Operating 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 communication For directive antennas, or broadcasting with omi-directional antennas Radio Transmission: the speech signals are converted to EM Power is transmitted in space towards destination EM 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 directions • Such 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

Applications: 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 an Exchange, and many exchanges to a tower

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 Broadside Patch Array Antennas Complete Mechanical Steering High Fabrication Cost. >12inch Phased Array Antennas ~6inch COST Proposed Solution Complete Mechanical Steering with limited range (due to beam tilt) SIW, Low Fabrication Cost Reflector Antennas for Stationary Reception Low Profile Reflector Antennas Complete Mechanical Steering Low Fabrication Cost. ~12 inch Mobility

Research Progress 12*64 Elements Slotted SIW Full Array 13 x 48 Elements Full Array Directivity 13x32 Elements SIW Array With Folded Feed Network 12x16 Elements SIW Sub-Array 13 x 6 elements Sub-Array 13 Elements Slotted Waveguide 12 Elements Slotted SIW Array Efficiency

Antennas for Mobile Systems

Why Do we need Reconfigurable Antennas? • Limited Space, and Volume • Trend to further miniaturization • Difficulty to attain Directivity • G=4pA/l2, 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 Multi- function Tiny Does it all

Broad Band Antenna Ant. Gain Ant. Gain Ant. Gain Frequency Frequency Frequency Multi-Band Antenna Antenna Alternatives for Multi-Radio Application Radio 1 Multiple Radios Radio 2 Radio 3 • Covers all bands of interest, Good for sim-ops • Higher Noise , Non Uniformity in Ant. Gain Radio n Reconfigurable Antenna • Covers few bands of interest, OOBnoise supp.  • Poor iso. between radios, stringent filter spec. • Very good noise immunity, high Flexibility • Requires switches, Poor for true sim-ops

Mini-Nested Patches

2nd Band DCS/PCS/IMT2000 2nd Band 802.11a 1st Band GSM850/900 1st Band 802.11b/g/n Reconfigurable Multiband

42mm Switch Locations 11mm 50cm coaxial cable 90mm 10mm p-i-n diodes Ground 50cm coaxial cable RF blocking resistor MEMS Switches DC Feeds Research Progress Reconfigurable Multi-band branched Monopole Antenna Reconfigurable Multi-band Twin PIFA Antenna with PIN diode switch “Maze” Reconfigurable Fractal Loop Antenna “mini-Maze” Reconfigurable Bent Monopole Antenna with MEMS 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.

Explosives Stand-off detection Security screening wand 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 Envelope Postal screening

Knife Wrapped in Newspaper Terahertz Images Can Reveal Objects Concealed Under Cloth, Paper, Tape, Even Behind Walls Objects Concealed Under clothes

See Through Prototype System Universal Automation Mechanism: Developed in Matlab Utilized GPIB bus and parallel port protocol

Diseased skin Skin Cancer Normal skin Powerful Medical Imaging Capabilities of THz White light image THz image Brain Dental THz device and probe (TeraView)

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): 015 Radar 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

Mode: Search Radar Azimuth (deg): 000 Radar Elevation (deg): 000

Mode: OFF Radar Azimuth (deg): 000 Radar Elevation (deg): 000

E&M/Communications Applications