The document discusses ultra-wideband (UWB) communication and antenna designs for UWB applications. It proposes a baseline UWB antenna and single, dual, and tri-band notch UWB antenna designs using capacitively loaded loop (CLL) elements. The CLL elements create band rejections at desired frequencies like WiMAX and WLAN bands. Parametric studies show how adjusting CLL length, gap size, and distance from feed affects band rejection performance. While the tri-band design achieves multiple notches, closely spaced bands are difficult to reject due to element coupling. Measured results validate the antenna designs and characteristics.

2. ULTRA WIDE BAND
COMMUNICATION
 Ultra-wideband is a radio technology which may be used at a
very low energy level for short-range, high-bandwidth
communications using a large portion of the radio spectrum.
 Federal Communication Commission(FCC) currently define
UWB in terms of a transmission from an antenna for which
the emitted signal bandwidth exceeds the lesser of 500
MHz or 20% of the center frequency
 The (FCC) approved the rules for the utilization of the 3.1–
10.6 GHz unlicensed band for commercial UWB
communications in 2002.
 Earlier known as pulse radio

3. Characteristics of UWB
very wide bandwidth(in gigahertz).
Low power spectral density.
Short broadcast time.
Pulse repetition rates can be high or low.
ability to determine the "time of flight" of
the transmission at various frequencies.
Overcomes multipath fading of
narrowband signals.

4. radar-imaging
technology
short-distance
applications,
such as PC
peripherals.
Intrusion
detection
locating and
tracking (using
High speed LAN /
WAN ( >20 Mbps)
Used in wireless
printers,
camcorders
distance
measurements
between radios).
Application
s of UWB

5. CHALLENGES FACED BY
ANTENNA DESIGNS FOR UWB
APPLICATIONS
1. Impedance matching
2.Radiation stability
3.compact size
4.low manufacturing cost
5.electromagnetic interference(EMI)

6. NEED FOR BAND NOTCHED
UBW ANTENNNA
Narrowband services which occupy frequency bands within the
designated UWB bandwidth are:
1. world interoperability for microwave access (WiMAX)
service from 3.3 to 3.6 Ghz;
2. 5.35 & 5.725–5.825 GHz for Wireless Local Area Network
(WLAN) services in US.
3. HIPERLAN/2 in Europe (5.15 to 5.35 GHz, 5.47 to 5.725
Ghz)
4. 7.25–7.745 (Down-Link) & 7.9–8.395 GHz (Up-Link) for X
band satellite communication services.
To mitigate any interference with these coexisting
systems, it is necessary to introduce a UWB antenna
that has intrinsic filtering properties at their service
frequencies.

7. BAND NOTCHED UBW
ANTENNNA
There are several methods with which one can achieve a
band-notched UWB antenna.
1. By embedding different shaped slots in the radiating
element or in its ground plane. Examples include U-shaped,
H-shaped or C-shaped slots ( Popular
approach ).
2. Complimentary split ring resonator (CSRR) structure.
Although those designs are low profile, achieve stable
radia- tion patterns, and have constant gain, the lower
WLAN band (5.15–5.35 GHz) was not rejected
successfully.

8. CAPACITIVELY LOADED LOOP
(CLL)
CLL helps to overcome the problem of previous designs
 Acts an artificial magnetic conductor for low profile antenna
applications
 Self resonant structure
 resonance frequency can be determined by its loop
inductance and the capacitances
 Simple and compact design
 High Q-characteristic
We can control the band-notched frequencies of the radiator,
while minimizing their space requirements, to achieve single,
dual, and tri-band notched-filter UWB antennas.

9. UWB ANTENNAS PROPOSED
IN THIS PAPER

10. 1. Baseline UWB Design

11. Basic characteristics of
baseline UBW antenna
 It is a top-loaded CLL-based UWB antenna implemented with
Rogers Duroid 5880 board material.
 relative permittivity of 2.2
 loss tangent =0.0009
 17 micrometer of electrodeposited copper
 Its overall size is 27 x 34 x 0.784 mm cube.
 It is fed by a microstrip line( W4=2.4 mm)
 50 ohm input impedance

12. Comparisons of the measured and
simulated VSWR values for the base-line
UWB antenna.

13. II. Single Band-Notched UWB
Antenna Design
•To reduce the EMI with
the WiMAX band, a band-notched
function covering
the interval 3.3– 3.6 GHz
is desired.
• CLL1 element (kept
close to the feed line) gets
strongly coupled to the
feed line
• It captures and stores all
of the input energy at its
resonance frequency and
thus creates a single
band-notched frequency
filter.

14. CALCULATION OF LENGTH OF CLL1
ELEMENT
The band-notched frequency is given approximately
by the expression
Where L(cll) is the total length of the CLL1 element
Given a desired resonance frequency, one can use this
expression to define the initial total length of the CLL1
element for an initial design.

15. GRAPH 1(Varying length of CLL
element):

16. GRAPH 2(Varying CLL
element gap sizes):

17. GRAPH 3(Varying distance between
CLL element and feed line):

18. GRAPH 4(Comparisons of the measured
and simulated VSWR values for single
band notch UWB antenna.)

19. III. Dual Band-Notched UWB
Antenna Design
•Designed to avoid
EMI in WiMAX (3.3–
3.6 Ghz), and the
lower WLAN (5.15–
5.35 GHz) band.
• an additional CLL
element added near
the feed line
dimensions of the
main radiator and
element remain the
same.
•Each CLL element
acts independently.

20. Comparisons of the measured and
simulated VSWR values for the dual
band notch UWB antenna

21. IV. Tri-Band Notched Antenna
Design •Designed to avoid
EMI in WiMAX, the
lower WLAN , and
the high WLAN
band.
•To adjust CLL3
element we
decrease the
length and gap
size of CLL2
simultaneously
• the higher
frequency WLAN
band is narrower
than the lower
one, the gap
between the
element and the
feed line should
also increase.

22. Comparisons of the measured and
simulated VSWR values for the tri
band notch UWB antenna

23. Efficiency and maximum gain
realized for tri-band UBW antenna

24. LIMITATION OF TRI BAND
NOTCHED UWB ANTENNA
●there is undesirable coupling between CLL2 and CLL3.
TO AVOID THIS: INCREASE THE DISTANCE BETWEEN
THE AND ELEMENTS
For example:
●shorten the total length of each CLL element and
●decrease the gap size in order to have a much smaller
sized CLL element
●then increase the distance between the and elements
IT LEADS TO DIFFICULTIES DUE TO LIMITATIONS OF
THE
FABRICATION TECHNIQUES

25. CONCLUSION:
 CLL-based single, dual and tri-band notched UWB antennas
were introduced in this paper.
 They were obtained by using three additional CLL elements.
Single- and dual-notched band antennas helped to explain
the performance characteristics of the tri-band designs.
 Parametric studies of all of these antennas provided
guidelines on how to control not only the band-notched
frequencies, but also the bandwidth of the rejected
frequencies as well.
 The tri-band notched design with the three CLL elements had
some sensitivities to achieve the band-notched
characteristics for the closely adjacent frequencies
associated with the lower and higher WLAN band.
 The comparisons between the measured and simulated
values for all UWB designs verified their predicted
performance characteristics, including stable radiation
patterns, high gain and radiation efficiencies, and broadband
matched impedance values for all radiating frequencies.