Thu, 07 Aug 2008 21:55:03 BST CiteULike: dcastro's efficiency http://www.citeulike.org/user/dcastro/tag/efficiency CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dcastro/article/3041465 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 48, No. 5. (2000), pp. 868-870.</i><br /><br />In this paper, the power input to the radiating element of an active microstrip patch antenna is measured using a small sensing patch, which is weakly coupled to a radiating edge. Combined with an estimate of patch radiation efficiency, this also yields a measurement of total radiated power. The method has advantages of convenience, insensitivity to room reflections, and a weakly frequency-dependent calibration factor A power and efficiency measurement technique for active patch antennas EA Elkhazmi NJ Mcewan NT Ali doi:10.1109/22.841888 Microwave Theory and Techniques, IEEE Transactions on, Vol. 48, No. 5. (2000), pp. 868-870. 2008-07-25T00:31:39-00:00 2000 Microwave Theory and Techniques, IEEE Transactions on 48 5 868 870 active antenna efficiency measurement patch power http://www.citeulike.org/user/dcastro/article/3041449 <i>Antennas and Propagation, IEEE Transactions on, Vol. 36, No. 1. (1988), pp. 136-139.</i><br /><br />Three methods for the measurement of antenna efficiency are evaluated: (1) the Wheeler cap method, (2) the radiometric method, and (3) the directivity/gain method. Each of these methods was used to measure the efficiency of four different printed antennas (three microstrip patches with various feeds, and an eight-element series-fed microstrip array). These methods and the experimental results which were obtained are discussed Comparison of three methods for the measurement of printed antenna efficiency DM Pozar B Kaufman doi:10.1109/8.1084 Antennas and Propagation, IEEE Transactions on, Vol. 36, No. 1. (1988), pp. 136-139. 2008-07-25T00:25:32-00:00 1988 Antennas and Propagation, IEEE Transactions on 36 1 136 139 antenna efficiency microstrip http://www.citeulike.org/user/dcastro/article/2933331 <i>Communications Magazine, IEEE, Vol. 17, No. 4. (1979), pp. 14-22.</i> Minimum shift keying: A spectrally efficient modulation S Pasupathy Communications Magazine, IEEE, Vol. 17, No. 4. (1979), pp. 14-22. 2008-06-27T10:41:09-00:00 1979 Communications Magazine, IEEE 17 4 14 22 efficiency modulation msk spectral http://www.citeulike.org/user/dcastro/article/2933329 <i>Vehicular Technology Conference, 2002. Proceedings. VTC 2002-Fall. 2002 IEEE 56th, Vol. 2 (2002), pp. 899-903 vol.2.</i><br /><br />The power efficiency of the linear modulation signals in terms of the required output back-off of the power amplifier is analyzed and compared, based on a simple approach that deals only with the knowledge of the statistical distribution of the instantaneous power of the input signals. The proposed method may also be useful for predicting the efficiency of the peak-to-average power reduction techniques for single-carrier and OFDM signals for a given level of the adjacent channel power ratio. As widely recognized, the result shows that the efficiency of the OFDM signal is considerably poor without peak power reduction. Thus the improvement of the power efficiency by simple clipping and filtering is also studied. Power efficiency comparison of OFDM and single-carrier signals H Ochiai doi:10.1109/VETECF.2002.1040730 Vehicular Technology Conference, 2002. Proceedings. VTC 2002-Fall. 2002 IEEE 56th, Vol. 2 (2002), pp. 899-903 vol.2. 2008-06-27T10:40:51-00:00 2002 Vehicular Technology Conference, 2002. Proceedings. VTC 2002-Fall. 2002 IEEE 56th 2 899 903 vol.2 efficiency ofdm power http://www.citeulike.org/user/dcastro/article/2858748 <i>Antennas and Propagation, IEEE Transactions on [legacy, pre - 1988], Vol. 34, No. 8. (1986), pp. 969-976.</i><br /><br />The numerical solution of circular microstrip antenna is carried out using the method of moment. The effect of the probe position, The dielectric permittivity of the substrate, and the substrate thickness on the radiation pattern and the mode excitation efficiency are studied. It is found that the probe position and the patch size can be used to control the mode excitation efficiency, and heigher order modes can be generated using only one feed location. Also, the finite ground plane can be used to improve the symmetry of the radiation patterns. The technique is general and can be used to investigate other scattering and antenna problems involving axisymmetric geometries. The effect of various parameters of circular microstrip antennas on their radiation efficiency and the mode excitation A Kishk L Shafai Antennas and Propagation, IEEE Transactions on [legacy, pre - 1988], Vol. 34, No. 8. (1986), pp. 969-976. 2008-06-03T11:01:05-00:00 1986 Antennas and Propagation, IEEE Transactions on [legacy, pre - 1988] 34 8 969 976 antenna circular efficiency microstrip patch http://www.citeulike.org/user/dcastro/article/2836663 <i>Antennas and Propagation, IEEE Transactions on, Vol. 39, No. 3. (1991), pp. 407-410.</i><br /><br />Simple approximate formulas for the input resistance, bandwidth, and radiation efficiency of a resonant rectangular microstrip patch are derived. These formulas become increasingly accurate as the substrate thickness decreases. Because the formulas are derived from approximations of a rigorous Sommerfeld solution, they provide insight into the effect of the substrate parameters on the patch properties, in addition to providing approximate design equations Simple approximate formulas for input resistance, bandwidth, and efficiency of a resonant rectangular patch DR Jackson NG Alexopoulos doi:10.1109/8.76341 Antennas and Propagation, IEEE Transactions on, Vol. 39, No. 3. (1991), pp. 407-410. 2008-05-27T07:10:39-00:00 1991 Antennas and Propagation, IEEE Transactions on 39 3 407 410 antenna bandwidth design efficiency impedance input patch http://www.citeulike.org/user/dcastro/article/2801349 <i>Antennas and Propagation Magazine, IEEE, Vol. 36, No. 1. (1994), pp. 16-19.</i><br /><br />The author discusses class-C FET/patch oscillators; in these, the microstrip-patch antenna serves multiple purposes: the patch radiates energy, acts as a resonant load, and as a feedback network. These integrated antenna/oscillators are capable of efficiencies which approach conventional non-radiating oscillator designs High-efficiency FET/microstrip-patch oscillators RD Martinez RC Compton doi:10.1109/74.262628 Antennas and Propagation Magazine, IEEE, Vol. 36, No. 1. (1994), pp. 16-19. 2008-05-15T11:25:35-00:00 1994 Antennas and Propagation Magazine, IEEE 36 1 16 19 efficiency fet high microstrip oscillator patch http://www.citeulike.org/user/dcastro/article/2782065 <i>Microwave Conference, 2000 Asia-Pacific (2000), pp. 888-894.</i><br /><br />In this paper, we present two novel design architectures that utilizing either a periodic structure or an active integrated antenna (AIA) for harmonic tuning in transmitter front-end designs. These techniques promise to significantly improve the power amplifier efficiency, reduce losses and weight, as well as maintaining good linearity requirements of advanced wireless communication systems. We will illustrate these two concepts through several design examples that have been developed recently, including a power amplifier integrated with novel PBG ground plane for harmonic tuning and four push-pull PA design examples, where the AIA concept is implemented to allow antenna to serve as a power combiner, a harmonic tuning load, in addition to its original functionality as a radiating element High efficiency transmitter front-ends integrated with planar antennas and PBG CY Hang WR Deal Yongxi Qian T Itoh doi:10.1109/APMC.2000.925972 Microwave Conference, 2000 Asia-Pacific (2000), pp. 888-894. 2008-05-10T00:03:23-00:00 2000 Microwave Conference, 2000 Asia-Pacific 888 894 antenna efficiency front-end high integrated pbg planar transmitter http://www.citeulike.org/user/dcastro/article/2774758 <i>Military Communications Conference, 1998. MILCOM 98. Proceedings., IEEE, Vol. 3 (1998), pp. 699-703 vol.3.</i><br /><br />This paper reports two techniques for optimizing harmonic termination in power amplifiers. In the first technique, the active antenna approach, the antenna element acts as radiator and as part of the output tuning circuit. The second method, based on photonic band-gap (PBG) structure, incorporates a periodic harmonic tuning structure for microstrip lines. In this structure, a periodic 2-D pattern is etched in the microstrip ground plane. A wide stopband suitable for broadband harmonic tuning, has been demonstrated experimentally. These methods yield high efficiency power amplifiers, and reduce unwanted radiation from the antenna at harmonics. Two power amplifier examples are presented Active antenna approach to high efficiency power amplifiers with EMI reduction V Radisic Yongxi Qian T Itoh doi:10.1109/MILCOM.1998.726914 Military Communications Conference, 1998. MILCOM 98. Proceedings., IEEE, Vol. 3 (1998), pp. 699-703 vol.3. 2008-05-09T08:35:16-00:00 1998 Military Communications Conference, 1998. MILCOM 98. Proceedings., IEEE 3 699 703 vol.3 active amplifier antenna efficiency high power http://www.citeulike.org/user/dcastro/article/2774720 <i>Microwave Symposium Digest, 2002 IEEE MTT-S International, Vol. 2 (2002), pp. 1317-1320.</i><br /><br />An X-band oscillating element can be achieved in compact form with class-E operation and high directivity. An annular ring is used both as the radiating element and microstrip feedback circuit for the class-E amplifier. A maximum conversion efficiency of the DC power consumption to radiated copolarized power is 55% at 10 GHz with maximum effective radiated power of 23.6 dBm and total radiated power of 15.5 dBm. This active antenna element is shown to be a good candidate for high aperture efficiency spatial power combining A 10 GHz integrated class-E oscillating annular ring element for high-efficiency transmitting arrays JA Hagerty Z Popovic doi:10.1109/MWSYM.2002.1011911 Microwave Symposium Digest, 2002 IEEE MTT-S International, Vol. 2 (2002), pp. 1317-1320. 2008-05-09T08:23:39-00:00 2002 Microwave Symposium Digest, 2002 IEEE MTT-S International 2 1317 1320 active antenna efficiency high integrated oscillator http://www.citeulike.org/user/dcastro/article/2774607 <i>Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 2 (1998), pp. 455-458 vol.2.</i><br /><br />This paper describes a high efficiency amplifier that uses the load presented by a patch antenna to work in class “E”. The resulting set is a high efficiency transmitting active antenna. The dimensions, shape and location of the feeding point in the antenna are selected to obtain an input impedance to force the transistor to work in class “E” at 885 MHz with very high collector efficiency: ηc=90%@Vcc=12.5, Pout=1.5 W High efficiency mode “E” amplifier powers high efficiency active transmitting patch antenna Ortega Asensio Gonzalez Jimenez Martin doi:10.1109/MWSYM.1998.705031 Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 2 (1998), pp. 455-458 vol.2. 2008-05-09T07:26:00-00:00 1998 Microwave Symposium Digest, 1998 IEEE MTT-S International 2 455 458 vol.2 active amplifier antenna efficiency high patch transmitter http://www.citeulike.org/user/dcastro/article/2774610 <i>Microwave Symposium Digest, 1999 IEEE MTT-S International, Vol. 2 (1999), pp. 663-666 vol.2.</i><br /><br />This work discusses the use of a microstrip-fed slot antenna to directly provide the necessary output match and harmonic tuning for a 10 GHz class-E power amplifier. There is no matching circuit at the output of the amplifier since the slot is designed to provide the correct impedance at the fundamental frequency and to present an open circuit at the second harmonic. This eliminates losses in the matching circuit and decreases circuit area. Since the class-E amplifier requires a complex output load, the designed slot antenna is not a resonant structure. The device used is an Alpha AFM04P2 MESFET, which has a maximum output power of about 21 dBm. The measured performance of the active antenna shows 74% drain efficiency, 62% power-added-efficiency (PAE), and 20 dBm output power at 10 GHz, at 5 dB gain compression. The PAE is greater than 50% in a 400 MHz bandwidth A 10 GHz high-efficiency active antenna MD Weiss Z Popovic doi:10.1109/MWSYM.1999.779848 Microwave Symposium Digest, 1999 IEEE MTT-S International, Vol. 2 (1999), pp. 663-666 vol.2. 2008-05-09T07:26:08-00:00 1999 Microwave Symposium Digest, 1999 IEEE MTT-S International 2 663 666 vol.2 active antenna efficiency high http://www.citeulike.org/user/dcastro/article/2774611 <i>Microwave Symposium Digest, 2002 IEEE MTT-S International, Vol. 3 (2002), pp. 1527-1530.</i><br /><br />This paper presents the design and implementation of a 10-GHz 4-element spatial power combiner. The GaAs-MESFET amplifiers are designed to operate in switched class-E mode, feeding dual-layer patch antennas. A Wilkinson combiner feed was designed for the input with 0.7 dB loss. The individual amplifiers operate at 64% drain efficiency and deliver 20.6 dBm output power. The total output power delivered from the active array is 26.6 dBm (0.46 W), for 20 dBm input power. The average drain efficiency of the amplifiers in the array is 70% and the power added efficiency is 57% A 10-GHz high-efficiency active antenna sub-array S Paji Z Popovi doi:10.1109/MWSYM.2002.1012146 Microwave Symposium Digest, 2002 IEEE MTT-S International, Vol. 3 (2002), pp. 1527-1530. 2008-05-09T07:26:10-00:00 2002 Microwave Symposium Digest, 2002 IEEE MTT-S International 3 1527 1530 active antenna array efficiency high http://www.citeulike.org/user/dcastro/article/2762226 <i>Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 1 (1998), pp. 327-330 vol.1.</i><br /><br />This paper presents several power amplifier approaches that promise to significantly improve efficiency, while meeting the linearity requirements of advanced, spectrally efficient wireless systems. The approaches include: a) use of active integrated antenna structures that provide harmonic terminations for high efficiency Class F amplifiers; b) integrated dc-dc converters for power conditioning and envelope restoration; c) switching mode amplifiers based on bipolar transistors with controlled saturation; and d) the use of band-pass delta-sigma modulators to tailor input signals Device and circuit approaches for improved linearity and efficiency in microwave transmitters PM Asbeck T Itoh Y Qian MF Chang L Milstein G Hanington PF Chen V Schultz DW Lee DW Lee J Arun A10 doi:10.1109/MWSYM.1998.689385 Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 1 (1998), pp. 327-330 vol.1. 2008-05-06T18:30:58-00:00 1998 Microwave Symposium Digest, 1998 IEEE MTT-S International 1 327 330 vol.1 efficiency microwave transmitter http://www.citeulike.org/user/dcastro/article/2762157 <i>Microwave Symposium Digest, 2002 IEEE MTT-S International, Vol. 2 (2002), pp. 913-916.</i><br /><br />This paper presents a new power combining scheme, which has either one or four amplifiers on depending upon the levels of input signal. This approach realized by utilizing a unique combiner that is lossless and has constant gain under both scenarios. As a result, for the system where variable output power is required, this combining scheme can be used in an amplifier design with optimum efficiency. Measurement data show 15% power efficiency for the four-amplifier scenario and 28% for the single amplifier scenario at 13dBm input power. We also investigate the possibility of using this combiner in an envelope tracking amplifier A new amplifier power combining scheme with optimum efficiency under variable outputs CY Hang Y Wang T Itoh doi:10.1109/MWSYM.2002.1011778 Microwave Symposium Digest, 2002 IEEE MTT-S International, Vol. 2 (2002), pp. 913-916. 2008-05-06T17:44:51-00:00 2002 Microwave Symposium Digest, 2002 IEEE MTT-S International 2 913 916 amplifier efficiency power http://www.citeulike.org/user/dcastro/article/2758012 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 53, No. 10. (2005), pp. 3206-3214.</i><br /><br />A novel fully integrated transmitter front-end with a simple structure is proposed to obtain both high power-added efficiency (PAE) and a compact RF-front structure. To have all these characteristics, a novel antenna operating as a radiator, a harmonic tuning circuit, and an output matching network of the power amplifier is proposed. Therefore, the direct integration of the output of the power amplifier and antenna can be achieved without any impedance transformers. From the measured results and fabrication, it is shown that the proposed transmitter front-end provides high PAE of 67.5% and compact and integrated RF-front structure by the size reduction of 43% compared with the conventional class-F active antenna for high PAE. A novel fully integrated transmitter front-end with high power-added efficiency Hyungrak Kim Ick-Jae Yoon Young Yoon doi:10.1109/TMTT.2005.855142 Microwave Theory and Techniques, IEEE Transactions on, Vol. 53, No. 10. (2005), pp. 3206-3214. 2008-05-05T14:11:58-00:00 2005 Microwave Theory and Techniques, IEEE Transactions on 53 10 3206 3214 antenna efficiency high integrated power transmitter http://www.citeulike.org/user/dcastro/article/2755639 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 46, No. 11. (1998), pp. 1901-1909.</i><br /><br />This paper presents three novel architectures for high-efficiency amplifiers relying on new harmonic-tuning techniques. These methods yield high-efficiency power amplifiers and reduce unwanted harmonic radiation from the transmitter front end. The first method uses the active integrated-antenna approach to perform harmonic tuning. The second method uses a nontraditional periodic microstrip filter, which allows broadband harmonic tuning. Finally, the third method combines the previous two approaches. Each technique is illustrated by a design example of a power amplifier integrated with an antenna. Guidelines for choosing the appropriate antenna structure and for designing the periodic structures are also presented. Another design issue is inclusion of the antenna and/or periodic structures into the amplifier simulation. To do this, a hybrid approach combining the finite-difference time-domain (FDTD) analysis and harmonic-balance simulation is employed Novel architectures for high-efficiency amplifiers for wireless applications V Radisic Y Qian T Itoh doi:10.1109/22.734508 Microwave Theory and Techniques, IEEE Transactions on, Vol. 46, No. 11. (1998), pp. 1901-1909. 2008-05-05T08:06:40-00:00 1998 Microwave Theory and Techniques, IEEE Transactions on 46 11 1901 1909 amplifier applications efficiency high wireless http://www.citeulike.org/user/dcastro/article/2755629 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 49, No. 6. (2001), pp. 1155-1161.</i><br /><br />This paper presents a C-band push-pull power amplifier integrated with a modified uniplanar quasi-Yagi antenna. In this circuit, corrugation is added to the truncated ground plane of the antenna so that it can be used for both out-of-phase power combining and second harmonic tuning. By using the active integrated antenna concept, this novel circuit eliminates the usage of an ordinary 180° hybrid at the power-amplifier output stage, therefore eliminating the losses associated with the hybrid, resulting in a compact and high-efficiency power-amplifier design with intrinsic second harmonic suppression. At an operating frequency of 4.15 GHz, a maximum measured power-added efficiency (PAE) of 60.9% at an output power of 28.2 dBm has been achieved. The measured PAE is above 50% over a 260-MHz bandwidth. Additionally, the second harmonic radiation is found to be 30 dB below the fundamental in both E- and H-planes. When the circuit is subjected to a two-tone test, the measured third-order intercept point is 37 dBm, about 10 dB above the P_{1 dB} point High-efficiency push-pull power amplifier integrated with quasi-Yagi antenna CY Hang WR Deal Yongxi Qian T Itoh doi:10.1109/22.925510 Microwave Theory and Techniques, IEEE Transactions on, Vol. 49, No. 6. (2001), pp. 1155-1161. 2008-05-05T08:04:57-00:00 2001 Microwave Theory and Techniques, IEEE Transactions on 49 6 1155 1161 active amplifier antenna efficiency high integrated power http://www.citeulike.org/user/dcastro/article/2713258 <i>Vehicular Technology Conference, 1993 IEEE 43rd (1993), pp. 38-41.</i><br /><br />A coherent F-QPSK modem radio technique is proposed for future generations of high-capacity personal communication services (PCSs) systems. F-QPSK is a constant envelope modulation that is 6 to 8 dB more power efficient than non-constant envelope signalings like the π/4 DQPSK as used in the US IS-54 digital cellular mobile radio and the Japanese Handyphone standards. A comprehensive evaluation of F-QPSK's adjacent channel interference (ACI) characteristics, spectral efficiency in b/s/Hz/m² and bit error rate (BER) performance in a PCS cellular environment is presented. The results are compared with Gaussian minimum shift keying (GMSK), which is the modulation format adopted in the current PCSs standards DECT and DCS1800. It is demonstrated that F-QPSK has an attainable spectral efficiency of 1.42 b/s/Hz, which is 51% higher than GMSK as used in DECT. The BER performance of F-QPSK is also more robust in both Rayleigh fading and CCI controlled environments F-QPSK-A superior modulation for future generations of high-capacity microcellular PCS systems PSK Leung K Feher doi:10.1109/VETEC.1993.507005 Vehicular Technology Conference, 1993 IEEE 43rd (1993), pp. 38-41. 2008-04-24T14:47:29-00:00 1993 Vehicular Technology Conference, 1993 IEEE 43rd 38 41 capacity efficiency high mobile modulation http://www.citeulike.org/user/dcastro/article/2678799 <i>Communications, 1994. ICC '94, SUPERCOMM/ICC '94, Conference Record, 'Serving Humanity Through Communications.' IEEE International Conference on (1994), pp. 645-649 vol.2.</i><br /><br />This paper presents a new coding scheme based on the association of a turbo-code with a bandwith efficient modulation. It is shown that the new coding scheme provides a substantial coding gain both on Gaussian channels and Rayleigh channels. On a Gaussian channel, it outperforms 64-state trellis-coded modulation (TCM) by 2.5 dB at the bit error rate (BER) of 10^-6. On a Rayleigh fading channel, it outperforms 64-state TCM optimized for that environment Turbo-codes and high spectral efficiency modulation S Le Goff A Glavieux C Berrou doi:10.1109/ICC.1994.368804 Communications, 1994. ICC '94, SUPERCOMM/ICC '94, Conference Record, 'Serving Humanity Through Communications.' IEEE International Conference on (1994), pp. 645-649 vol.2. 2008-04-16T19:26:48-00:00 1994 Communications, 1994. ICC '94, SUPERCOMM/ICC '94, Conference Record, 'Serving Humanity Through Communications.' IEEE International Conference on 645 649 vol.2 efficiency high modulation spectral turbocode http://www.citeulike.org/user/dcastro/article/2674620 <i>Antenna Technology: Small and Smart Antennas Metamaterials and Applications, 2007. IWAT '07. International Workshop on (2007), pp. 384-387.</i><br /><br />The fundamental limits of the gain, efficiency and Q-value of an antenna put severe restrictions on small antennas. In this paper it is discussed how one can avoid low efficiency and high Q-values in small antennas by examining the far-field pattern of the antenna. The analysis is based on the expansion of the electromagnetic fields in terms of vector spherical harmonics. Efficiency, gain and Q of antennas A Karlsson doi:10.1109/IWAT.2007.370155 Antenna Technology: Small and Smart Antennas Metamaterials and Applications, 2007. IWAT '07. International Workshop on (2007), pp. 384-387. 2008-04-15T18:01:31-00:00 2007 Antenna Technology: Small and Smart Antennas Metamaterials and Applications, 2007. IWAT '07. International Workshop on 384 387 antenna efficiency gain http://www.citeulike.org/user/dcastro/article/2042842 <i>Selected Areas in Communications, IEEE Journal on, Vol. 16, No. 2. (1998), pp. 206-218.</i><br /><br />We present a bandwidth-efficient channel coding scheme that has an overall structure similar to binary turbo codes, but employs trellis-coded modulation (TCM) codes (including multidimensional codes) as component codes. The combination of turbo codes with powerful bandwidth-efficient component codes leads to a straightforward encoder structure, and allows iterative decoding in analogy to the binary turbo decoder. However, certain special conditions may need to be met at the encoder, and the iterative decoder needs to be adapted to the decoding of the component TCM codes. The scheme has been investigated for 8-PSK, 16-QAM, and 64-QAM modulation schemes with varying overall bandwidth efficiencies. A simple code choice based on the minimal distance of the punctured component code has also been performed. The interset distances of the partitioning tree can be used to fix the number of coded and uncoded bits. We derive the symbol-by-symbol MAP component decoder operating in the log domain, and apply methods of reducing decoder complexity. Simulation results are presented and compare the scheme with traditional TCM as well as turbo codes with Gray mapping. The results show that the novel scheme is very powerful, yet of modest complexity since simple component codes are used Bandwidth-efficient turbo trellis-coded modulation using punctured component codes P Robertson T Worz doi:10.1109/49.661109 Selected Areas in Communications, IEEE Journal on, Vol. 16, No. 2. (1998), pp. 206-218. 2007-12-02T09:23:56-00:00 1998 Selected Areas in Communications, IEEE Journal on 16 2 206 218 bandwidth code efficiency modulation puncturing trellis http://www.citeulike.org/user/dcastro/article/2648156 <i>Antennas and Propagation, IEEE Transactions on, Vol. 56, No. 3. (2008), pp. 691-707.</i><br /><br /><para> Planar two-dimensional (2D) and volumetric three-dimensional (3D) metamaterial-inspired efficient electrically-small antennas that are easy to design; are easy and inexpensive to build; and are easy to test; are reported, i.e., the EZ antenna systems. The proposed 2D and 3D electrical- and magnetic-based EZ antennas are shown to be naturally matched to a 50 <formula formulatype="inline"><tex>$Omega$</tex> </formula> source, i.e., without the introduction of a matching network. It is demonstrated numerically that these EZ antennas have high radiation efficiencies with very good impedance matching between the source and the antenna and, hence, that they have high overall efficiencies. The reported 2D and 3D EZ antenna designs are linearly scalable to a wide range of frequencies and yet maintain their easy-to-build characteristics. Several versions of the 2D EZ antennas were fabricated and tested. The measurement results confirm the performance predictions. The EZ antennas systems may provide attractive alternatives to existing electrically-small antennas. </para> Metamaterial-Inspired Efficient Electrically Small Antennas A Erentok RW Ziolkowski doi:10.1109/TAP.2008.916949 Antennas and Propagation, IEEE Transactions on, Vol. 56, No. 3. (2008), pp. 691-707. 2008-04-10T06:45:45-00:00 2008 Antennas and Propagation, IEEE Transactions on 56 3 691 707 antenna efficiency metamaterial small http://www.citeulike.org/user/dcastro/article/2622453 <i>Communications, 1990. ICC 90, Including Supercomm Technical Sessions. SUPERCOMM/ICC '90. Conference Record., IEEE International Conference on (1990), pp. 631-635 vol.2.</i><br /><br />The use of nonlinear biasing techniques in importance sampling (IS) simulations is discussed. For tail probability estimation, two new nonlinear IS (NLIS) approaches are presented: shift of absolute values (SAV) and sample elimination (SE). In the case of linear systems with Gaussian input, the SAV method is shown to be uniformly more efficient than the linear techniques and very robust with respect to suboptimal parameterization. With respect to suboptimal choice of its parameter, the efficiency of the SE method is more sensitive than that of all other IS techniques discussed. Both NLIS methods are found to be easily implementable alternatives to the standard linear IS(LIS) techniques. The estimation of very-low-interval probabilities is considered as a new field for the application of IS techniques. The author presents both an LIS and an NLIS approach for this problem and provides performance analyses. A uniform bound on the required sample size is obtained for both techniques, thus emphasizing their high efficiency. Both methods are shown to be very robust with respect to suboptimal parameterization Nonlinear importance sampling techniques for efficient simulation of communication systems HJ Schlebusch doi:10.1109/ICC.1990.117155 Communications, 1990. ICC 90, Including Supercomm Technical Sessions. SUPERCOMM/ICC '90. Conference Record., IEEE International Conference on (1990), pp. 631-635 vol.2. 2008-04-02T06:41:56-00:00 1990 Communications, 1990. ICC 90, Including Supercomm Technical Sessions. SUPERCOMM/ICC '90. Conference Record., IEEE International Conference on 631 635 vol.2 efficiency importance nonlinear sampling simulation technique http://www.citeulike.org/user/dcastro/article/2431119 <i>Wireless Communications, IEEE Transactions on, Vol. 4, No. 1. (2005), pp. 149-162.</i><br /><br />Delay estimation in direct-sequence code-division multiple-access (DS-CDMA) systems is necessary for accurate code synchronization and for applications such as mobile phone positioning. Multipath propagation is among the main sources of error in the DS-CDMA delay estimation process, together with multiple access interference and non-line-of-sight (NLOS) propagation. This paper provides a review of main delay estimation techniques, existing in the literature so far, which are able to cope with multipath propagation, together with our novel delay estimation techniques proposed in the context of DS-CDMA systems. The performance of all these techniques is compared through analysis and simulations, considering also their relative computational complexity and required prior information. Starting from the traditional delay locked loops (DLL) and their improved variants, we discuss several recently introduced delay estimation techniques able to cope with multipath propagation. The characterization of these methods is given in a unified framework, suited for both rectangular and root raised cosine pulse shapes. The main focus in the performance comparison of the algorithms is on the closely-spaced multipath scenario, since this situation is the most challenging for achieving diversity gain with low delay spreads and for estimating LOS component with high accuracy in positioning applications. Highly efficient techniques for mitigating the effects of multipath propagation in DS-CDMA delay estimation ES Lohan R Hamila A Lakhzouri M Renfors doi:10.1109/TWC.2004.840231 Wireless Communications, IEEE Transactions on, Vol. 4, No. 1. (2005), pp. 149-162. 2008-02-26T19:30:58-00:00 2005 Wireless Communications, IEEE Transactions on 4 1 149 162 cdma delay efficiency estimation high mitigation multipath http://www.citeulike.org/user/dcastro/article/2431118 <i></i><br /><br />In this paper, a high efficiency class-AB pushpull power amplifier is designed utilizing a novel photonic band-gap (PBG) ground plane. This design allows simultaneous tuning of both second and the third harmonics, thus, results in a high efficient power amplifier design. The measured PAE is 63.8% at an output power of 28.2dBm. In addition, the measured IP3 is 45 dBm, about 17 dB above the P 1dB point. . High Efficiency S-band Class AB Push-Pull Power Amplifier with Wide Band Harmonic Suppression Cynthia Hang Yongxi Qian Tatsuo Itoh 2008-02-26T19:29:59-00:00 amplifier efficiency high power wideband