Uwb Antenna: Mrs.A.Petrishia Trichy
Uwb Antenna: Mrs.A.Petrishia Trichy
Uwb Antenna: Mrs.A.Petrishia Trichy
Mrs.A.Petrishia
Trichy
OUTLINE
Introduction
UWB systems
UWB Antenna-Example
Conclusion
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Ultra-Wide-Band Radio Communication
UWB is a technology developed to transfer large amounts of data wirelessly
over short distances over a very wide spectrum of frequencies in a short
period of time.
The amount of spectrum occupied by a UWB signal, i.e. the bandwidth of the UWB
signal is at least 25% of the center frequency. For example, a UWB signal centered
at 2 GHz would have a minimum bandwidth of 500 MHz and the minimum
bandwidth of a UWB signal centered at 4 GHz would be 1 GHz. The most common
technique for generating a UWB signal is to transmit pulses with durations less than
1 nanosecond.
UWB technology has the capacity to handle the very high bandwidths required to
transport multiple audio and video streams.
UWB will be ideally suited for transmitting data between consumer electronics (CE),
PC peripherals, and mobile devices within short range at very high speeds while
consuming little power.
This technology operates at a level that most systems interpret as noise and, as a
result, does not cause interference to other radios such as cell phones, cordless
phones or broadcast television sets.
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Ultra-Wide-Band Radio Communication
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UWB Advantages
Extremely Difficult to Intercept - LPI/LPD. Wideband pulsed radar spreads
the signal and allows more users access to a limited amount of scarce
frequency spectrum.
Multipath Immunity - A low path loss and low energy density minimizes
interference to other services. UWB is very tolerant of interference,
enabling operation within buildings, urban areas, and forests.
Precision Network-wide timing - Real-time, continuous position location
down to a centimeter of resolution results in precision geolocation
systems.
Low Cost - Requires minimal components resulting in small size and weight
Low Power - Typical consumption is in microwatts
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UWB Applications
Communications - High Speed WLANs, Mobile Ad-Hoc wireless networks,
Groundwave Communications, Handheld and Network Radios, Intra-home
and Intra-office communication. Stealthy communications provide
significant potential for military, law enforcement, and commercial
applications.
Sensor Networks - Ground penetrating Radar that detects and identifies
targets hidden in foliage, buildings or beneath the ground. Intrusion
Detection Radars, Obstacle Avoidance Radars, and Short-range motion
sensing.
Tracking/Positioning - Precision Geolocation Systems and high-resolution
imaging. Indoor and outdoor tracking down to less than a centimeter. Good
for emergency services, inventory tracking, and asset safety and security.
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What is UWB system?
Ultra Wideband High Bandwidth, FCC - 2002
IEEE 802.15.3a
1 0 1
Impulse
Modulation
(FCC Min=500Mhz)
Communication
Narrowband
0 1 0 1
Frequency
Modulation
2.4 GHz
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UWB Synonyms
Other terms associated with Ultra-wideband
Impulse
Short-Pulse
Non-Sinusoidal
Carrier-less
Time domain
Super wideband
Fast Frequency Chirp and
Mono-Pulse
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Specifications of UWB
As per FCC definition, any transmission scheme that has a
fractional bandwidth (FBW) greater than or equal to 0.20 or an
absolute bandwidth greater than or equal to 500 MHz is said to
be UWB system
FBW = f H -f L
fc
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UWB bands in the world
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UWB system features
Unlicensed spectrum
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By Shannon's capacity theory,
S
C = B.log 2 1 +
N
It is easier to increase the bit rate (capacity) by increasing the bandwidth instead of
the power, given the linear-versus-logarithmic relationship.
Pt
d
Pr
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Comparison of UWB with other standards
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PSD of some common wireless broadcast and communication
systems.
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UWB BASIC CHARACTERISTICS (Cont...)
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Effective and Efficient UWB antenna is a critical one over all UWB
System design
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UWB Antenna Classification
Directional Vs Omni Directional:
High gain or directional antennas concentrate energy into a
narrower solid angle
Electric Vs magnetic :
Electric antennas are characterized by intense electric fields
close to the antenna
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Types of UWB Antenna
Single band Vs multi-Narrow band:
Typical UWB antennas used in the past are multi-narrow band
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Dispersive Non dispersive
Chirp like waveform Radiates more
Waveform varies at compact and non
different azimuth angles. dispersive wave form
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Category of UWB antennas
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Requirements to design UWB Antennas
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Challenges in UWB Antenna Design
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UWB Antennas
Bow-tie
Relatively high input impedance
Requires a matching balun to make it usable with 50 ohm system
Tapered slot
Two dimensional microstrip
Resister loaded dipole
Low gain and low efficiency
Diamond dipole: developed by Time Domain Corp.
Emits a waveform similar to a Gaussian third derivative
75 % efficiency with about 3:1 VSWR
Discone
High performance
3-D structure: difficult to manufacture
Bicone
High performance
3-D structure: difficult to manufacture
Log-periodic
Spiral
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Antenna-Example
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UWB is a short range wireless standard which can support variety of
applications
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Conclusion
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