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ABSTRACT: A compact coplanar waveguide (CPW)-fed microstrip antenna with pattern and polarization diversities is proposed in this article.By making use of even and odd modes of a CPW feed network, a circular patch antenna operating at TM11 and TM01 modes can be excited, which results in broadside and conical monopole-like radiation patterns being achieved at an overlapping frequency range for 2.4GHz WLAN applications. The impedance bandwidth (VSWR ≤ 2) are 520 MHz (2.18–2.70 GHz, 21%) and 480 MHz (2.26–2.74 GHz, 20%) for broadside TM11 mode and conical TM01 mode, respectively. The measured isolation is better than 22 dB across the working bandwidth. The measured radiation pattern and gain of the proposed antenna are compared with simulation results. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:968–972, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25932
Microwave and Optical Technology Letters 04/2011; 53(5):968 - 972. · 0.62 Impact Factor
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ABSTRACT: A conformal switchable antenna system mounted on a cylindrical surface is proposed, simulated, prototyped and measured. The antenna system is composed of several tri-polarization antennas operating at 2.4 GHz band. It is shown that this antenna system realizes a quasi-isotropic pattern without any nulls over a complete spherical surface. Specifically, it is shown that by using three tri-polarization antennas and switching among them, a complete spherical coverage could be achieved without any nulls and with a power gain larger than 2.5 dBi over more than 90 percent of a spherical surface surrounding the antenna system. Furthermore, it is shown that the performance of the antenna system does not deteriorate with the increase in the diameter of the mounting cylinder, thus facilitating the implementation of the proposed design in many applications including telemetry, satellites, and aircraft. Both simulation and experimental results of the radiation patterns are presented in this paper.
IEEE Transactions on Antennas and Propagation 04/2011; · 2.15 Impact Factor
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ABSTRACT: This paper proposes a novel Doherty power amplifier (PA) that realizes concurrent dual-band operation. A T-network is used to implement a dual-band impedance transformer and a phase shifter simultaneously. To prove the concept a PA is designed operating at 900 MHz and 2000 MHz simultaneously. In the experimental results, the concurrent dual-band PA achieves a drain efficiency of 39.8% with an output power of 36.9 dBm at the 5 dB back-off point from saturated output power at 900 MHz, and a drain efficiency of 41.4% with an output power of 36.2 dBm at the 5 dB back-off point at 2000 MHz. Compared to the balanced PA, the drain efficiency of the proposed PA has been approximately doubled in the entire back-off power region.
Microwave Conference Proceedings (APMC), 2010 Asia-Pacific; 01/2011
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ABSTRACT: A novel compact wideband antenna, which adopts a multi-state switchable matching circuit, is proposed in this paper. The design of the switchable matching is systematically studied and a two-step iterative procedure is used to obtain optimized values for both the bandwidth division between the various stages and the matching circuit components in each stage. Without loss of generality, a meander line monopole, with dimensions of 80 10 10 , is used as the radiator in the proposed wideband antenna design. To validate the proposed new design, a four-state matching circuit controlled by four PIN diodes is fabricated and measured. The reflection coefficient of the prototype antenna is found to be better than , and the peak gain is higher than across the 470-770 MHz bandwidth for the Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) application.
IEEE Transactions on Antennas and Propagation 12/2010; · 2.15 Impact Factor
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ABSTRACT: A novel concurrent dual-mode class-E power amplifier is proposed.Owing to the stub tapped transformer and compensation inductance, a dual-band output matching network is achieved. Experimental results show the output powers of 38.1 and 38.6 dBm, and the drain efficiency of 63.4% and 65.1% are obtained at 920 MHz and 1200 MHz, respectively. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:171–174, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25684
Microwave and Optical Technology Letters 11/2010; 53(1):171 - 174. · 0.62 Impact Factor
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ABSTRACT: Total Isotropic Sensitivity (TIS) refers to the average receiver sensitivity across the entire radiated sphere around the device, which represents the overall receiving capability of the Device under Test (DUT). The designed GPS devices will not be qualified to manufacture unless they meet a minimum certified standard prompted by Cellular Telecommunications & Internet Association.
Antennas and Propagation Society International Symposium (APSURSI), 2010 IEEE; 08/2010
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ABSTRACT: A reconfigurable varactor-based matching circuit is proposed in this article. The introduction of an extra series inductor into the matching circuit reduces the required capacitance ratio of the varactor from 27.9 to 8.2. A meander line DVB-H antenna is designed and fabricated to verify the concept. The dimensions of the prototype antenna are 80 × 10 × 10 mm3, and it can provide better than −10 dB return loss across the 470–770 MHz bandwidth. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1786–1789, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25317
Microwave and Optical Technology Letters 05/2010; 52(8):1786 - 1789. · 0.62 Impact Factor
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ABSTRACT: A novel shunt-fed triband printed two-element collinear dipole array is presented in this letter. The planar dipole array configuration is designed using two shunt-fed back-to-back dipole elements with omnidirectional pattern. The motivation for this work was to devise a novel feed structure that has an advantage of structural simplicity with good performance. The proposed antenna can provide the required bands of GSM850 (824-894 MHz), DCS (1710-1880 MHz), and PCS (1850-1990 MHz) with S<sub>11</sub> <; -10 dB. A prototype array antenna is fabricated and measured. Good omnidirectional radiation with gain variations less than 1.5 dBi in the azimuth plane has been obtained. Enhanced antenna gain about 3.4 3.8 dBi for GSM850 band and about 3.85.5 dBi for DCS/PCS bands are achieved. It is significant that the designed triband dipole array maintained good radiation efficiency values at all bands.
IEEE Antennas and Wireless Propagation Letters 02/2010; · 1.37 Impact Factor
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ABSTRACT: Abstract-In this letter, a novel hybrid-fed circular patch antenna operating with TM<sub>11</sub> and TM<sub>01</sub> modes is presented. By making use of a hybrid feed network, the two modes can be operated at an overlapped frequency range for 2.4-GHz WLAN applications, while TM<sub>11</sub> mode reveals good broadside radiation patterns and TM<sub>01</sub> mode shows monopole-like radiation patterns. The proposed antenna is fabricated and tested. The measured gain for the broadside mode is 7.1-9.1 dBi from 2.16 to 2.72 GHz (23.0%), and for the conical mode 3.4-4.3 dBi from 2.14 to 2.64 GHz (20.5%). High isolation (<; -40 dB) between the two feeding ports for the entire impedance bandwidth of the proposed antenna is achieved. The planar dual-port antenna provides different patterns and polarizations to take advantage of the pattern and polarization diversity for modern mobile communications.
IEEE Antennas and Wireless Propagation Letters 02/2010; · 1.37 Impact Factor
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ABSTRACT: A polarization reconfigurable slot antenna with a novel coplanar waveguide (CPW)-to-slotline transition for wireless local area networks (WLANs) is proposed and tested. The antenna consists of a square slot, a reconfigurable CPW-to-slotline transition, and two p-i-n diodes. No extra matching structure is needed for modes transiting, which makes it much more compact than all reference designs. The -10 dB bandwidths of an antenna with an implemented bias circuit are 610 (25.4%) and 680 MHz (28.3%) for vertical and horizontal polarizations, respectively. The radiation pattern and gain of the proposed antenna are also tested, and the radiation pattern data were compared to simulation results.
IEEE Antennas and Wireless Propagation Letters 02/2010; · 1.37 Impact Factor
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ABSTRACT: A dual-polarization coplanar waveguide (CPW)-fed slot antenna is proposed in this letter. By exploiting the even and odd modes of a CPW structure, two orthogonal polarizations can be excited in a slot aperture by the same feeding CPW, which results in a compact dual-polarization antenna design with very good isolation between the ports. The -10-dB reflection coefficient bandwidths of two polarizations are 670 MHz (27.9%) for one polarization and 850 MHz (35.4%) for the other, and the isolation between the two ports in the WLAN band is better than -32.6 dB. The radiation pattern and efficiency of the proposed antenna are also measured, and radiation pattern data are compared with simulation results.
IEEE Antennas and Wireless Propagation Letters 02/2010; · 1.37 Impact Factor
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ABSTRACT: An endfire beam-switchable antenna array, which is designed for vehicular mobile application regulated by the IEEE 802.11p standard, is proposed in this letter. The antenna is a linear array with four L-shaped elements separated by a quarter of a wavelength. The horizontal beams of L-elements point to four different directions, and this reduces the antenna height, decreases the mutual coupling between elements, and also eliminates the blind zone in the broadside direction. The antenna array has two isolated ports. By switching between two ports, the endfire radiation pattern can be switched toward opposite directions. A prototype antenna is built to verify the concept. The gain of the prototype is better than 6 dBi, and the impedance matching is better than -14 dB in the working band (5.8505.925 GHz).
IEEE Antennas and Wireless Propagation Letters 02/2010; · 1.37 Impact Factor
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ABSTRACT: A measurement system to measure the 3-D spatial response of the indoor multi-polarized channel is presented and fabricated, the channel response data are also acquired to demonstrate the validity of that system For the indoor radio channel is quasi-static, the rotating directivity antennas are applied in the transmit/receive ends to avoiding the deterioration factors(the mutual coupling, pattern distortion of antenna array), which is different from the traditional channel measurement equipment. For the convenience of applying different antenna, the working band of that system is wide. And the automatic 3-D capable rotating system is designed to obtain the complete channel model while previous measurements mostly can only achieve the 2-D channel response. Furthermore, the antennas with different polarization can also applied in the transmit/receive end to construct the channel model with polarization. Beamforming arithmetic is used in data processing to improve the angle discrimination of the system. For the indoor radio channel is considered quasi-static, the system can be used for measurements of indoor radio channel. The measurement using this system has been carried out, and the measurement results confirm the system to be helpful and applicable for measurements of indoor channel.
Microwave Conference, 2009. APMC 2009. Asia Pacific; 01/2010
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ABSTRACT: Measurement on dipole antenna with a light polarized nano-material(PNM) reflector has been carried out in this paper. Based on the PNM textile fabricated by Tsinghua-Foxconn Nanotechnology center, we set up a dipole antenna with a PNM reflector formed by 20 layers of carbon nanotube textile. To evaluate the performance of PNM reflector, we measured the radiation pattern of the antenna with PNM reflector in different alignments. The results show the dipole achieved 2dB gain higher than that case without PNM by using parallel aligned PNM reflector, and the front to back ratio in radiation pattern is better than 10db. The reflector is almost invisible while the alignment of the PNM is orthogonal to the dipole.
Microwave Symposium Digest, 2009. MTT '09. IEEE MTT-S International; 07/2009
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ABSTRACT: A frequency reconfigurable hexagonal patch antenna with switchable slot is proposed in this paper. By changing the slot status, two resonant frequency bands at 2.29GHz and 2.46GHz respectively can be obtained without special matching network, and the radiation patterns at the two frequency bands are very similar to each other. The simulated and measured results are presented to validate this concept, which could be used for bandwidth enhancement. This proposed antenna is interesting for wideband wireless applications because of its low profile, light weight and easy fabrication.
Antennas and Propagation Society International Symposium, 2009. APSURSI '09. IEEE; 07/2009
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ABSTRACT: A compact and planar dual-antenna structure is reported which combines a printed monopole and a half-slot antenna to provide dual polarization. Different excited current modes are utilized to obtain low mutual coupling between elements. A prototype is fabricated and the measured results are presented. Relative bandwidth of 23.5% and isolation of better than 23 dB are achieved.
Antennas and Propagation Society International Symposium, 2009. APSURSI '09. IEEE; 07/2009
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ABSTRACT: A novel compact planar inverted-F antenna (PIFA) with reconfigurable feedings for GSM/PCS/DCS applications is proposed in this paper. The U-shaped PIFA with only one branch is folded into 3 planes is designed to reduce the dimensions. The antenna occupies a relatively small volume of 50*7*7 mm<sup>3</sup>. Two feeds can be switched to achieve two different matching states, and GSM/PCS/DCS bands can be covered by the first and second resonants with S11<-7.3dB.
Antennas and Propagation Society International Symposium, 2009. APSURSI '09. IEEE; 07/2009
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ABSTRACT: A novel wrist conformal dual-band antenna structure is proposed for application in watch-type wireless devices. Simulation results show that this structure can achieve good performance in dual GSM bands and high efficiency when worn on hand. Based on this structure, a dual-element diversity antenna is also proposed. More research regarding this novel structure will be done in the future.
Antennas and Propagation Society International Symposium, 2009. APSURSI '09. IEEE; 07/2009
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ABSTRACT: A compact inverted-F antenna (IFA) with switchable feeds is proposed in this letter. The antenna occupies a relatively small volume of 50 times 7 times 7 mm<sup>3</sup>. Two pin diodes are used to switch the antenna between two different working states. The antenna can provide the required bands of GSM850 (824-894 MHz), GSM900 (890-960 MHz), DCS (1710-1880 MHz), and PCS (1850-1990 MHz) with S11 < -10 dB. Measurements including return loss, radiation patterns, and gain are presented to verify the proposed design of antenna.
IEEE Antennas and Wireless Propagation Letters 02/2009; · 1.37 Impact Factor
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ABSTRACT: The design and characterization of a conformal tripolarization antenna with three independent ports and three orthogonal polarizations is presented. The antenna uses both proximity (slot) coupling and probe-fed ports to reduce isolation and improve polarization purity. The measured bandwidth of the -10-dB return loss is found to be 190 MHz (2.4-2.59 GHz). Measurements across the working bandwidth also show that the isolations among the three ports are better than -16 , -30 , and -40 dB, respectively. Design parameters and experimental results are presented.
IEEE Antennas and Wireless Propagation Letters 02/2009; · 1.37 Impact Factor
