A compact, printed, ultrawideband (UWB) monopole antenna suitable to be as an internal antenna attractive for future UWB applications is demonstrated. The proposed antenna is of a small form factor with the dimensions 6 mm × 33 mm and can easily be fed by 50-ohms mini-cable line. The antenna mainly comprises a monopole antenna, a feeding strip and a ground plane, all printed on a small FR4 substrate. The monopole antenna is printed on both layers of the substrate with an end portion on the back for control of the first/lower resonant mode of the antenna. The feeding strip in between the monopole antenna and the ground plane is further offset to achieve better impedance matching and proper upper-edge operating frequency. With the proposed antenna structure, which provides an operating bandwidth of larger than 2.7 GHz, the impedance bandwidth by 10-dB return loss can easily cover the 3.1–4.85 GHz band, the lower band of the UWB operation.

1. 2009 IEEE AP-S
International Symposium
Compact Coaxial-Line-Fed Printed
Monopole Antenna for Lower-
Band Ultrawideband Applications
1
Saou-Wen Su, Ph.D. and 2Fa-Shian Chang
1
Network Access Strategic Business Unit,
Lite-On Technology Corp., Taipei, Taiwan
2
Dept. of Electronics, Cheng Shiu University,
Kaohsiung, Taiwan
*E-mail: stephen.su@liteon.com
Jun 05, 2009

2. Outlines
(I) Introduction
UWB fact sheet and Band Group
Conventional UWB monopoles
UWB WUSB dongle antenna
(II) Design Consideration & Results
Constructed prototype and test results
Parameterized studies
(III) UWB Bloom & Doom
(IV) Conclusion
2

3. UWB Fact Sheet
UWB (Ultra-Wideband), RF technologies formerly
classified for military applications
Approval (Revision of Part 15) of FCC, Feb 2002, for
commercial communications
High-speed > 100 Mb/sec, short-range < 10 m
radius, low-power < -41 dBm/MHz
Systems in the 3.1-10.6 GHz band with BW > 25%
or > *1.5 GHz (*the center frequency > 6 GHz)
Suited for IEEE 802.15 WPAN (Wireless Personal
Area Network)
3

4. UWB Band Group 1 to 5
Band numbering: relationship between center
frequency fc and band ID number nb is given:
spacing of 528 MHz within 3100-10600 MHz
Band Group allocation
FIVE Band Group comprises:
FOUR has three bands
ONE has two bands
UECMA-368 - High Rate Ultra Wideband PHY and MAC Standard,
4 http://www.wimedia.org/en/resources/eis.asp?id=contact

5. UWB Band Group 1 to 5
FIVE Band Group comprises:
Band numbering: relationship between center
FOUR has three bands
frequency fc and band ID number nb is given:
ONE has two bands
spacing of 528 MHz within 3100-10600 MHz
Band Group allocation
FIVE Band Group comprises:
FOUR has three bands
ONE has two bands
UECMA-368 - High Rate Ultra Wideband PHY and MAC Standard,
5 http://www.wimedia.org/en/resources/eis.asp?id=contact

6. UWB Band Group 1 to 5
FIVE Band Group comprises:
FOUR has three bands
ONE has two bands
Band Group allocation
6

7. Conventional UWB Antennas 1
UWB planar monopole antennas
Antenna perpendicular to large ground plane
Impedance matching controlled by
shaping antenna geometry and/or
adjusting antenna structure around feeding
MOTL, vol 42, Sep 2004 IEEE AP, vol 53, Apr 2005
7

8. Conventional UWB Antennas 2
Numerous UWB planar monopole antennas
in various shapes and sizes
8

9. UWB Antenna for WUSB Dongle
Antenna comprises:
a pair of radiating arms
a bevel-feed transition
UWB WUSB-dongle antennas
are very promising applications
9 US/TW patent pending IEEE AP, vol 55, Apr 2007

10. Design Consideration 1-
Antenna Configuration
Compact printed UWB antenna:
printed on both layers of a 0.4-mm substrate
compact structure: 6 (W) x 33 (L) mm (0.06- x 0.34-lambda at
3.1 GHz)
comprises three portions: a monopole antenna, a feeding strip
and a ground plane
10

11. Design Consideration 2-
Design Principles
offsetting feeding strip is to achieve a larger
upper-edge operating frequency; at the
same time, to satisfy required impedance
matching around middle frequency band
small portion is cut out
from ground plane to
accommodate feeding
strip
end portion on bottom layer is to provide
additional lower resonant mode for controlling
lower-edge frequency
11

12. Experimental Results 1-
Impedance Bandwidth (Proposed Antenna)
10-dB RL BW (2.77 GHz)
covers lower-band UWB
of 3.1-4.85 GHz
near optimal value of
feed gap d is 2 mm
12

13. Experimental Results 2-
Impedance Bandwidth (Reference Antennas)
no end portion (L = 0) no end portion (L = 0)
no offset feeding (h = 0)
Ref. 1: single resonance at 3.4 GHz is excited below 4.2 GHz;
Ref. 2: simple, rectangular monopole antenna with a narrow
bandwidth (700 MHz, 3305-4005 MHz) only
13

14. Experimental Results 3-
2-D Far-filed radiation patterns
3100 MHz
4000 MHz
4850 MHz
14

15. Experimental Results 4-
3-D far-filed radiation patterns
Measurement was conducted with
great-circle method at 3 x 3 x 7 m
anechoic chamber
Omnidirectional-radiation patterns
obtained are similar to conventional,
wire-dipole radiation characteristics
15

16. Experimental Results 5-
3-D far-filed radiation patterns
Gain varies in a range of 2.8-3.7 dBi;
Radiation efficiency exceeds 82% overall
(%)
Note that input power is 0 dBm (default value) for
16 antenna OTA measurement (passive)

17. Parameterized Studies 1-
Small feed gap d
feed gap d
Feed gap d varies from 1 to 3 mm;
Upper-edge frequency is largely affected
17

18. Parameterized Studies 2-
End portion length L
End portion L
Two resonant modes: one fundamental and one
additional without and with end portion are excited
< 4.4 GHz;
Additional resonant mode is excited to achieve a
18 smaller lower-edge frequency < 3.1 GHz

19. Parameterized Studies 3-
Distance h of offset feeding strip
distance h of feeding strip
Upper-edge frequency increases as h decreases;
Lower-edge frequency, fundamental and additional
resonant modes are unchanged;
19
Hump > 10 dB occurs when h < 6 mm

20. Bloom and Doom
“The time is ripe for a special
issue on UWB antennas that
captures this progress and
provides insight to where
FCC authorized UWB in 2002
UWB antenna design will go
in the future.”
20 “Ultra-wideband antenna,” Intl Journal of Antennas and Propag, vol 2008

21. Bloom and Doom
UWB Start-ups shuts down
WiQuest Closed (Oct. 2008)
TZero Closed (Feb. 2009)
Radiospire Closed (Arp. 2009)
PulseLink Lay-off 2008
Staccato Communications and Artimi merged (Nov.
2008): Staccato Communications and Artimi announced a
merger between the two companies.
WiMedia, the UWB industry group folded (Mar. 2009):
WiMedia to transfer specification development to Bluetooth
and Wireless USB
21

22. Conclusion
Proposed coaxial-line-fed UWB
antenna is compact (6 mm x 33 mm)
and easy to fabricate on PCB
Can be concealed in a narrow space
between the panel and housing of a
LCD display or HDTV, for future
lower-band (3.1-4.85 GHz) UWB
applications
Time domain property of the antenna
will be studied in the future
22

23. NA SBU ODM/OEM Product Line
advanced consumer-electronics devices WLAN/Bluetooth/WiMAX modules
USB form factor
full/half-size PCIe
MP3/PMP
WiMAX
communications
digital photo frame
network hub
BT dongle/PCMCIA
internet radio
USB hub
antennas
AP/router
digital TV tuners
Bluetooth headset/car hands free kit
TV dongle
half-size mini-card
23 DVB-T/WLAN combo

24. Lite-On Global Headquarters
THANK YOU FOR YOUR ATTENTION!
24