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Psat (dBm) 15.8* 12.3 14.5 12.6 13.8 13.8 for 60 GHz transformer-coupled CMOS power amplifiers, IEEE J
PAE (%) 9.4* 8.8 25.7 6.9 12.6 7 Solid-State Circuits 44 (2009), 2733–2744.
Supply (V) 2.2 1 1.8 1 1.8 1.1 4. A. Siligaris, Y. Hamada, C. Mounet, C. Raynaud, B. Martineau, N.
Gain (dB) 16.9* 5.6 16 10 30 6 Deparis, N. Rolland, M. Fukaishi, and P. Vincent, A 60 GHz power
23-dB BW (GHz) 36 22 21 21 19 18 amplifier with 14.5 dBm saturation power and 25% peak PAE in
Fractional BW (%) 66.7 36.7 35 35 31.7 30 CMOS 65 nm SOI, IEEE J Solid-State Circuits 45 (2010), 1286–1294.
Area (mm2) 0.18 0.25 0.57 0.64 0.33 0.38 5. N. Kurita and H. Kondoh, 60 GHz and 80 GHz wide band power
amplifier MMICs in 90 nm CMOS technology, In: Proceedings
IEEE Radio Frequency Integrated Circuits (RFIC) Symposium, Bos-
(36–72 GHz), representing a 66.7% fractional bandwidth. Figure
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6. J.-L. Kuo, Z.-M. Tsai, K.-Y. Lin, and H. Wang, A 50 to 70 GHz
put power at 44, 56, and 62 GHz. Peak gain at these frequencies power amplifier using 90 nm CMOS technology, IEEE Microwave
are 17.6, 16.1, and 16.9 dB, respectively. In Figure 8, the meas- Wireless Comp Lett 19 (2009), 45–47.
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ied supply voltage are shown, again at 44, 56, and 62 GHz. 50-to-67 GHz ESD-protected power amplifiers in digital 45nm LP
PAE degrades as supply voltage is increased over 2.2 V. In both CMOS, In: IEEE International Solid-State Circuits Conference (ISSCC)
Figures 7 and 8, the similar large signal characteristics measured Digest Technical Papers, San Francisco, CA, 2009, pp. 382–383.
at the three different frequencies demonstrate the excellent 8. J. Kim, J.-O. Plouchart, N. Zamdmer, R. Trzcenski, R. Groves, M.
wideband performance of the PA. Sherony, Y. Tan, M. Talbi, J. Safran, and L. Wagner, A 12dBm
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than 30% fractional bandwidth [3–7]. Q-band CMOS PAs to
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date have not achieved a fractional bandwidth of greater than 9. J.-O. Plouchart, J. Kim, N. Zamdmer, L.-H. Lu, M. Sherony, Y.
30% and are therefore not listed. Among the previous CMOS Tan, R. Groves, R. Trzcinski, M. Talbi, A. Ray, and L. Wagner, A
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over the stage-of-the-art. It also has the highest saturated output (2004), 1455–1461.
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4. CONCLUSION C 2014 Wiley Periodicals, Inc.

V
We present a 36 to 72 GHz PA in 45-nm SOI CMOS. The wide
bandwidth is achieved by adopting a two-stage topology with VERY COMPACT MULTIBAND CHIP
counterposed resonances in the matching networks. At 62 GHz, ANTENNA FOR GNSS-WiFi-WiMAX
the PA has a saturated output power of 15.8 dBm, 9.4% PAE,
APPLICATIONS
and 16.9 dB gain with a 2.2-V supply.
Yu-Jiun Ren and James Warden
ACKNOWLEDGMENTS Nokia Inc., San Diego, CA 92127; Corresponding author:
yjren03@gmail.com
This work was supported by the Defense Advanced Research Proj-
ects Agency (DARPA) ELASTx program and the US ARL Army
Research Office under award number W911NF-10-1-0088. Authors Received 2 May 2013
thank D. Williams at NIST and H. Kim, R. Devine and R. Drang-
meister at MIT Lincoln Lab for assistance in measurements. ABSTRACT: A very compact multiband internal antenna for handsets
and tablets is presented. The proposed antenna is targeted to cover pop-
ular noncellular applications including GNSS, WiFi (IEEE 802.11a/b/g),
and WiMax (Bands 3A/4/5). This work examines a new ceramic material
suitable for the internal antenna design which gives a shorter guided
wavelength and multiple resonances to achieve antenna size reduction,
sufficient space utilization, and bandwidth increase. The occupied vol-
ume of the antenna radiator is only 12 3 4 3 3 mm3, approximately
equal to 0.06km 3 0.02km 3 0.016km (km is the longest wavelength of
the applications) so the antenna can be placed in the device flexibly.
The proposed antenna should be the smallest antenna covering GNSS-
WiFi-WiMax ever reported. V C 2014 Wiley Periodicals, Inc. Microwave

Opt Technol Lett 56:169–175, 2014; View this article online at wileyon-
linelibrary.com. DOI 10.1002/mop.28056

Figure 9 Die micrograph. [Color figure can be viewed in the online Key words: compact; monopole; mobile antenna; multiband antenna;
issue, which is available at wileyonlinelibrary.com] ceramic

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 56, No. 1, January 2014 169
Figure 1 (a) Configuration of the substrate and the antenna location; (b) the geometry of the proposed antenna; (c) photo of the antenna prototype.
[Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com]

1. INTRODUCTION of supporting even newer bands. Additionally, modern handset

Mobile and portable devices are required to support a wide and tablet devices are facing severe industrial design constraints
range of wireless technologies. WiFi connection in the 2.4-GHz and unfriendly environments to antennas. Then, the antenna
band using IEEE802.11b/g is almost ubiquitous for smart design has to be very discrete depending on the frequency band
phones and tablets. WiFi operating in the 5-GHz band based on of operation and environment.
IEEE802.11a has also become quite popular in recent years To address the difficulties of integrating antennas in handsets
because of the transmission speed and security point of view or tablets, many efforts have been delivered, especially to the
[1–3]. Bluetooth applications in the 2.4-GHz band have become cellular “main antenna” design. Some of these designs are able
a must in almost all of the mobile devices. At the same time, to cover selected bands of GPS, WiFi, Bluetooth, WiMax, and
the function of GNSS concurrently supported has gradually Wibro [8–13]. However, their combinations may not be the best
become a requirement to support location guidance and emer- topology from the prospect of the circuit tree because of the
gency assistance [4,5]. scale of transmitting powers, radio functions, and unavailable
While the above bands already exist in mobile phones, RF front-end switches. Although it seems easier to arrange these
WiMax technology of IEEE 802.16 has come into play for long narrow-band side antennas (single-band antenna, not combined
distance wireless access for both mobile phones and tablets with any other application) [14], it becomes tougher to sepa-
[6,7]. Furthermore, long-term evolution technologies are also rately allocate them in the device while more requests are
considered as potential candidates for future mobile phone and assigned to the main antenna. Hence, a wideband auxiliary
tablet antennas for high data rate communication allowing use antenna to cover interested noncellular bands is desired when
of these products any time and anywhere. It is already a chal- the design of mobile devices has become challenging than ever.
lenge to incorporate the necessary antennas to support the above In this article, a compact multiband internal antenna is devel-
bands into mobile phones and tablets without the consideration oped for mobile handsets and tablets to cover GPS and

170 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 56, No. 1, January 2014 DOI 10.1002/mop
 design is promising to be an internal antenna for handset and
tablet applications.

2. MULTIBAND ANTENNA DESIGN

Figure 1 shows the geometry of the proposed antenna with a
FR4 PCB as the system circuit board. Only a small portion of
the ground-clearance area (15 3 40 mm2) is occupied by the
proposed antenna. The dimension of the antenna carrier is 12 3
4 3 3 (Lc 3 Wc 3 hc) mm3, corresponding to 0.06km 3 0.02km
3 0.016km where km is the longest wavelength of the covered
bands, that is, 1575 MHz (fm) of the GPS frequency. The carrier
is made by the ceramic material with a relative permittivity of
6.45 and loss tangent of 0.0011. The antenna carrier can be
rotated or relocated to other locations on the PCB to give a
Figure 2 Simulated and measured return losses of the proposed more flexible accommodation for the system layout. The maxi-
antenna. [Color figure can be viewed in the online issue, which is avail- mum length of the carrier is only 0.06km which does not require
able at wileyonlinelibrary.com]
a long transmission line to feed the antenna and does not need
any matching component. Design parameters of the proposed
GLONASS (GNSS band, 1575.42–1602 MHz), dual-band WiFi antenna are given by: Ls 5 90 mm, Ws 5 40 mm, Lg 5 80 mm,
(2400–2480 and 4900–5825 MHz), and WiMax (Bands 3A/4/5, Lp 5 4 mm, Wp 5 1.5 mm, Lc 5 12 mm, Wc 5 4 mm, hc 5 3 mm,
i.e., 2500–2700 and 3300–3600 MHz) applications. To pursue La 5 1 mm, Lb 5 3 mm, Wf 5 1 mm, Wh 5 0.8 mm, Wl 5 0.5
such an antenna, a high-contrast, low-loss ceramic material has mm, Ga 5 1.2 mm, Gb 5 0.5 mm, Gc 5 1 mm, Lf 5 2 mm,
been used to achieve significant antenna miniaturization and Wf 5 1.5 mm, Lh 5 1.5 mm, and Ll 5 1.5 mm. Figure 1(c) shows
trace routing. Unlike the PIFA structure popularly used in many the picture of the antenna prototype.
mobile phones to reduce the antenna size [1,3–5,10–12] the pro- The antenna adopts a monopole structure to simplify the
posed monopole pattern of the antenna has an even smaller vol- design and thus no any shorting pin or via hole is required. The
ume and can be printed on the dielectric antenna carrier, which ability of covering a very wide bandwidth is primarily due to
has a direct point-to-point contact to the feeding port on the the combinations of multiple resonances from the two resonant
PCB, so this antenna carrier can be viewed as a built component branches and their mutual coupling. The two major branches in
for easy mechanical installation. This low-profile and low-cost this antenna contribute to low-band and high-band. Low-band

Figure 3 Simulated surface current distributions at (a) 1575 MHz, (b) 2400 MHz, (c) 3300 MHz, and (d) 5150 MHz. [Color figure can be viewed in
the online issue, which is available at wileyonlinelibrary.com]

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 56, No. 1, January 2014 171
 TABLE 1 Measured Radiation Efficiency and Total Gain

GPS (Upper
Band GPS (Free Space) Hemisphere)
Frequency (MHz) 1575 1575
Efficiency (%) 79 39
Gain (dBi) 2.81 n/a

Band WLAN (2.4G) and BT WLAN (5G)

Frequency(MHz) 2400 2440 2480 5150 5350 5820
Efficiency (%) 71 74 69 52 43 38
Gain (dBi) 2.05 2.24 1.8 1.11 0.44 20.5

Band WiMax(Band3A) WiMax (Band 4/5)

Frequency (MHz) 2500 2600 2690 3300 3400 3600
Figure 4 Simulated return loss of the proposed antenna, with different Efficiency (%) 71 72 71 67 61 53
dimensions of the ground plane. [Color figure can be viewed in the Gain (dBi) 2.02 1.81 1.93 1.58 1.42 0.8
online issue, which is available at wileyonlinelibrary.com] All are measured in the free space condition; h is equal to 0-90 degree
for the upper hemisphere condition.
(longer) branch is the one giving the GNSS band and its band-
width can be controlled by Wl and Gb. The high-band (shorter)
branch provides WiFi 2.4-GHz band and WiMax Band 3A

Figure 5 Simulated current distributions with different ground plane dimensions: (a) 1575 MHz, Lg 5 80 mm; (b) 1575 MHz, Lg 5 10 mm; (c) 2400
MHz, Lg 5 80 mm; (d) 2400 MHz, Lg 5 10 mm. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com]

172 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 56, No. 1, January 2014 DOI 10.1002/mop
Figure 6 Measured radiation patterns at (a) 1575 MHz, (b) 2400 MHz, (c) 3300 MHz, and (d) 5150 MHz. The left/middle/right plot shows the pat-
terns on the xy/xz/yz plane (blue solid line: Eh; green dash line: E/). [Color figure can be viewed in the online issue, which is available at
wileyonlinelibrary.com]

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 56, No. 1, January 2014 173
because of its wider trace width (Wh), which affect the band- in similar levels, 70% and 2 dBi. The field strength, and thus
width. WiMax Band 4 and Band 5 are coming from the second the gain, is reduced slowly as the frequency increases in 3300–
harmonic of the low-band branch, while the mutual coupling, 5800 MHz, which is because of the destructive cancelation of
affected by Ga and Gc, from these two branches also impacts high-order modes. Within WiFi 5-GHz band, the maximum effi-
those frequencies between. La and Lb help to fine tune the first ciency is 57% and the gain is lower than 0 dBi when the fre-
resonance of these two branches. The ceramic material further quency is over 5350 MHz.
enhances the bandwidth of the antenna. The desired bandwidth The radiation patterns on xy, xz, and yz planes are shown in
of WiFi 5-GHz band is very wide, ideally 4900–5825 MHz to Figure 6. At all of these frequencies, the radiation patterns on
cover the worldwide operation, so it is more difficult to realize the xy plane are nearly omnidirectional in either Eh or E/, like a
this through a single-antenna radiator. Here, WiFi 5-GHz band monopole antenna, which means the antenna can be relocated to
is achieved by the third harmonic of the low-band branch cover- any other location on the PCB such as center top or bottom but
ing lower 5-GHz frequencies, plus the radiation from the short the shape of patterns can be maintained. The patterns in the
strip of the feeding area (Lp 3 Wp) covering higher 5-GHz fre- same level of the GHz are similar due to the similar resonant
quencies. This short strip behaves like a tiny monopole antenna modes. Therefore, only one typical pattern is represented within
around the 5-GHz bands. each GHz range. It is noted that the antenna operating at the
GNSS band has very similar upper hemisphere and lower hemi-
sphere patterns as well as the efficiency, which means the
3. RESULTS AND DISCUSSIONS antenna can provide almost the same performance as the device
The return loss of the proposed antenna is shown in Figure 2, is rotated due to the user. Although the GNSS function has been
where the measured resonances match the simulated results gradually equipped into many mobile phones and tablets and tel-
well. Some of the discrepancy is due to the antenna fabrication ecommunication carriers have specified a solid requirement to
and assembling errors. As the antenna prototype is implemented the GNSS antenna especially for the upper hemisphere, this fea-
in the lab, not the massive production, the accuracy of the trace ture is attractive and flexible for the antenna placement of devi-
widths is limited not less than 0.5 mm at this time so that the ces. It can be seen that the patterns at 3300 and 5150 MHz are
hand-cut works can be done locally. The antenna is sufficient to similar, especially on xz and yz planes, which is because they
cover all of GPS/GLONASS, WiFi, and WiMax bands as what are excited by similar resonant mechanisms. The current distri-
targeted where the WiFi bandwidth coverage includes North bution has several unequal peaks and nulls on the radiating
America, Europe, and Japan as well. high-band and low-band braches that reflects to the appearance
Figure 3 shows simulated average current distributions. As of radiation patterns.
the current distributions at neighboring frequencies are similar,
four representative cases are presented here. It is obvious a high
current is on the low-band branch to excite the GNSS band. In 4. CONCLUSION
2400–2700 MHz, the major current goes on the high-band
A very compact mobile antenna for handset and tablet applica-
branch. In 3300–3600 MHz, the stronger current is on the low-
tions has been developed. According to author’s knowledge, this
band branch but the high-band branch also contributes to the
monopole-based multiband antenna is the smallest GNSS–WiFi–
resonance; hence the radiation can be viewed as the slot reso-
WiMax antenna ever reported, not occupied a large PCB area
nance between them that is affected by Ga. In 4900–5825 MHz,
but only relying on the antenna’s harmonic resonances and
it can be seen that most of the current concentrate on the very
mutual coupling. The reliance to the system ground plane is
short strip of the feeding area and a small portion is on the low-
very low. Compared to a similar previous works including the
band branch. The current on the high-band branch is relatively
GPS band, the antenna dimension has been significantly
weaker than the other two. Above investigations help realize the
reduced. The proposed antenna is even smaller than dual-/tri-
design concept and verify the proposed antenna topology.
band antennas designed for similar applications [1–3,6,7]. The
One feature of this antenna is its dependence on the PCB
antenna concept has been verified with good antenna
ground plane can be reduced. Figure 4 shows the return loss of
characteristics.
the antenna while the ground plane length Lg has been changed
from the initial value of 80 mm to a very small value of 10
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always stronger than those on the PCB ground plane, which 2. A.G. Alhaddad, R.A. Abd-Alhameed, D. Zhou, C.H. See, M.
does not rely on the chassis mode to enhance the radiation. This Usman, Z. Zainal Abidin, and P.S. Excell, Dual-band balanced hand-
advantage provides more flexibility for the handset/tablet set antenna for WLAN application, In: 2009 Loughborough Anten-
antenna design while it may be tough to have a perfect and solid nas and Propagation Conference, Loughborough, UK, November
ground in the device. Two examples at GPS band and WiFi 2.4- 2009, pp. 681–684.
GHz band are shown in Figure 5; similar phenomenon has been 3. H. Wang and M. Zheng, An internal triple-band WLAN antenna,
observed in WiMax band and WiFi 5-GHz band as well. IEEE Antennas Wireless Propag Lett 10 (2011), 569–572.
The radiation performance of the antenna is summarized in 4. C.C.-H. Lin, L.-G. Lai, K.-K. Tiong, and G.-Y. Chen, A novel on-
glass antenna for mobile handset applications, In: 2012 International
Table 1. The maximum efficiency of 78% (5 21 dB) happens
Symposium on Computer, Consumer and Control, Taichung, Taiwan,
at the GPS frequency, while the efficiency of the upper hemi-
pp. 236–239.
sphere is 39%, half of the total efficiency. This is a good indica- 5. A.A. Serra, P. Nepa, G. Manara, and R. Massini, IEEE Trans Anten-
tor for the user experience about the GPS, which will be nas Propag 58 (2010), 1060–1066.
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antenna for mobile handsets, IEEE Trans Antennas Propag 54
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C 2014 Wiley Periodicals, Inc.
V issue, which is available at wileyonlinelibrary.com]

COMPACT UWB MONOPOLE ANTENNA Federal Communication Commission [1], UWB systems have
WITH ENHANCED BANDWIDTH USING received phenomenal gravitation in wireless communication.
ROTATED L-SHAPED SLOTS AND PARA- Designing an antenna to operate in the UWB band is quite a
SITIC STRUCTURES challenge because it has to satisfy the requirements such as ultra
wide impedance bandwidth, omnidirectional radiation pattern,
Nasser Ojaroudi constant gain, high radiation efficiency, constant group delay,
Department of Electrical Engineering, Germi Branch, Islamic Azad low profile, easy manufacturing and so forth [2]. In UWB com-
University, Germi, Iran; Corresponding author: n_ojaroudi@srttu.edu munication systems, one of key issues is the design of a com-
pact antenna while providing wideband characteristic over the
Received 3 August 2013 whole operating band. Consequently, a number of microstrip
antennas with different geometries have been experimentally
ABSTRACT: In this article, a new design of compact ultrawideband characterized [3–8].
(UWB) monopole antenna is presented .The antenna consists of a ordi- Three new small wideband printed monopole antennas with
nary square radiating patch and a ground plane with pairs of rotated L- notched ground plane using rotated T-shaped, open-circuit, and
shaped slots and parasitic structures. By cutting a pair of rotated L- G-shaped notches in the upper edge of ground plane to achieve
shaped slots and also by embedding a pair of rotate L-shaped conduc- the maximum impedance bandwidth were proposed in Ref. 9–
tor-backed plane in air gap distance, additional resonances are excited 11]. Some methods are used to obtain the multiresonance func-
and much wider impedance bandwidth can be produced. Also, the usable tion in the literature [12–15].
upper frequency of the antenna is extended from 10.3 to 18.31 GHz.
In this article, a different method is proposed to obtain the
Simulated and measured results show that the antenna design exhibits
very wideband bandwidth for the compact monopole antenna. In
an operating bandwidth (VSWR < 2) from 3.09 to 18.31 GHz which pro-
vides a wide usable fractional bandwidth of more than 140%. The pro- the proposed antenna, we use pairs of L-shaped slots and con-
posed antenna has an ordinary square radiating patch, therefore, ductor backed plane, which provides a wide usable fractional
displays a good omnidirectional radiation pattern even at higher fre-
quencies. The antenna configuration is simple, easy to fabricate, and
can be integrated into UWB systems. V C 2014 Wiley Periodicals, Inc.
TABLE 1 Final Parameter Values of the Antenna
Microwave Opt Technol Lett 56:175–178, 2014; View this article online
at wileyonlinelibrary.com. DOI 10.1002/mop.28055 Parameter Wsub Wsub hsub W L Wf
Value (mm) 12 18 1.6 10 10 2
Key words: bandwidth enhancement; L-shaped structure; monopole Parameter Lf W1 L1 W2 L2 W3
antenna; ultrawideband applications Value (mm) 7 5.5 2.5 5 2 3.5
Parameter L3 W4 L4 W5 L5 W6
1. INTRODUCTION Value (mm) 3 3 2.25 2.25 1.75 0.5
Parameter L6 L7 d d1 d2 Lgnd
After allocation of the frequency band from 3.1 to 10.6 GHz for
Value (mm) 2.25 0.5 0.5 1.5 0.75 3.5
the commercial use of ultrawideband (UWB) systems by the

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 56, No. 1, January 2014 175