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Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 2006"


Journal ArticleDOI
Abstract: A new method of analysis is presented in this paper for the determination of complex propagation constants in substrate integrated waveguides (SIWs) This method makes use of the concept of surface impedance to model the rows of conducting cylinders, and the proposed model is then solved by combining a method of moments and a transverse resonance procedure The proposed method is further applied to extract results in terms of parametric curves and graphs which demonstrate fundamental and interesting wave guidance and leakage properties of this type of periodic waveguide Useful design rules are extracted from this analysis, suggesting that appropriate design parameters and regions should be carefully selected for practical applications In addition, comprehensive review and comparisons with published results are also presented to show the performance and accuracy of the proposed modeling technique Practical measurements of fabricated samples with different levels of loss have confirmed the accuracy of this new method and validity of design rules

660 citations


Journal ArticleDOI
Abstract: Photonic signal processing offers the prospect of realizing extremely high multigigahertz sampling frequencies, overcoming inherent electronic limitations. This stems from the intrinsic excellent delay properties of optical delay lines. These processors provide new capabilities for realizing high time-bandwidth operation and high-resolution performance. In-fiber signal processors are inherently compatible with fiber-optic microwave systems and can provide connectivity with built-in signal conditioning. Fundamental principles of photonic signal processing, including sampling, tuning, and noise, are discussed. Structures that can extend the performance of photonic signal processors are presented, including methods for improving the filter shape characteristics of interference mitigation filters, techniques to increase the stopband attenuation of bandpass filters, and methods to achieve large free spectral range. Several photonic signal processors, including high-resolution microwave filters, widely tunable filters, arbitrary waveform generators, and fast signal correlators, are discussed. Techniques to solve the fundamental noise problem in photonic signal processors are described, and coherence-free structures for few-tap notch filters are discussed. Finally, a new concept for realizing multiple-tap coherence-free processor filters, based on a new frequency-shifting technique, is presented. The structure not only eliminates the phase-induced intensity noise limitation, but can also generate a large number of taps to enable the achievement of processors with high performance and high resolution.

621 citations


Journal ArticleDOI
Abstract: This paper is divided into two major parts. Following a brief introduction that establishes some definitions and assumptions, Section II updates our earlier study on the limits of the RF performance of optical links. Section III reviews progress since our 1997 review paper in the development of devices enabling link performance closer to these limits, including (but not limited to): 1) cascade lasers that permit broad-band direct modulation links with gain >0 dB; 2) injection-locked edge- and surface-emitting lasers at 1300 and 1550 nm with modulation frequency responses as great as 40 GHz; 3) modulators with improved performance, especially electroabsorption modulators that now have switching voltages as low as 0.36 V, or handle optical powers as great as 60 mW, or have bandwidths as great as 50 GHz (but not all three of these in one device yet); and 4) high-speed photodetectors with high saturation currents, e.g., a 20-GHz device with a saturation current of 90 mA and a 55-GHz device with saturation at 50 mA. We conclude in Section IV by summarizing the component developments necessary for higher performance RF-over-fiber links, i.e.: 1) semiconductor lasers (for direct modulation) that have higher slope efficiency and bandwidth and lower relative intensity noise (RIN) at reasonable bias current levels; 2) continuous wave (CW) lasers (for external modulation) with higher fiber-coupled power and lower RIN; 3) higher frequency lower loss external modulators with more linear transfer functions and lower V/sub /spl pi// that can withstand larger CW optical powers; and 4) photodetectors with higher responsivity and bandwidth that respond linearly even when illuminated by greater average optical powers.

406 citations


Journal ArticleDOI
TL;DR: The models with memory, PH, and RBFNN, showed better cross-validation performance, in terms of lower model errors, than a static polynomial for the hardest cross validation of the 2G PA.
Abstract: A comparative study of nonlinear behavioral models with memory for radio-frequency power amplifier (PAs) is presented. The models are static polynomial, parallel Hammerstein (PH), Volterra, and radial basis-function neural network (RBFNN). Two PAs were investigated: one was designed for the third-generation (3G) mobile telecommunication systems and one was designed for the second-generation (2G). The RBFNN reduced the total model error slightly more than the PH, but the error out of band was significantly lower for the PH. The Volterra was found to give a lower model error than did a PH of the same nonlinear order and memory depth. The PH could give a lower model error than the best Volterra, since the former could be identified with a higher nonlinear order and memory depth. The qualitative conclusions are the same for the 2G and 3G PAs, but the model errors are smaller for the latter. For the 3G PA, a static polynomial gave a low model error as low as the best PH and lower than the RBFNN for the hardest cross validation. The models with memory, PH, and RBFNN, showed better cross-validation performance, in terms of lower model errors, than a static polynomial for the hardest cross validation of the 2G PA

367 citations


Journal ArticleDOI
Abstract: In this paper, we report results on an original way to excite surface waves on a single-wire transmission line. Although these waves were proposed many decades ago by Goubau, the novelty of our structures is to achieve a broadband planar excitement. This configuration is very well suited for the terahertz frequency range and allows the investigation of biological entities with high spatial resolution with the use of novel biomicroelectromechanical systems, which include microfluidic functions. From experimental results, we compare different types of transitions from coplanar waveguides, and different substrates are also used. We show that the excitation is highly efficient and broadband for structures on a quartz substrate

363 citations


Journal ArticleDOI
Abstract: A comparison of envelope elimination and restoration (EER) and envelope tracking (ET) is discussed and a "hybrid" wideband EER power amplifier (PA) for the WLAN 802.11g system is proposed. A 60% efficiency (the output envelope signal power/input dc power) DC-20-MHz wideband envelope amplifier is designed for wideband EER and wideband ET (WBET) applications. A design method is developed to optimize the efficiency of the envelope amplifier for a given peak-to-average ratio and average slew rate of the envelope signal. An experimental "hybrid" Class-E EER system shows an overall efficiency (modulated RF output power/envelope amplifier dc input power) of 36% and power-added efficiency (the modulated RF output power/envelope amplifier dc input power plus RF input power) of 28% for a WLAN 802.11g signal at 19-dBm (80 mW) output power at 2.4 GHz. Digital predistortion, time alignment, and memory effect mitigation are implemented. The measured 3% error vector magnitude exceeds the 802.11g specification for 5% for a 54-Mb/s modulation signal

335 citations


Journal ArticleDOI
Abstract: A high-efficiency wideband code-division multiple-access (W-CDMA) base-station amplifier is presented using high-performance GaN heterostructure field-effect transistors to achieve high gain and efficiency with good linearity For high efficiency, class J/E operation was employed, which can attain up to 80% efficiency over a wide range of input powers and power supply voltages For nonconstant envelope input, the average efficiency is further increased by employing the envelope-tracking architecture using a wide-bandwidth high-efficiency envelope amplifier The linearity of overall system is enhanced by digital pre-distortion The measured average power-added efficiency of the amplifier is as high as 507% for a W-CDMA modulated signal with peak-to-average power ratio of 767 dB at an average output power of 372 W and gain of 100 dB We believe that this corresponds to the best efficiency performance among reported base-station power amplifiers for W-CDMA The measured error vector magnitude is as low as 174% with adjacent channel leakage ratio of -510 dBc at an offset frequency of 5 MHz

319 citations


Journal ArticleDOI
Abstract: Magnetic properties were imparted to a naturally nonmagnetic material by metallic inclusions. A patch antenna tested the performance of the magnetic metamaterial as a substrate and validated that a single substrate can achieve a range of miniaturization values. The effective medium metamaterial substrate employed electromagnetically small embedded circuits (ECs) to achieve permeability and permittivity greater than that of the host dielectric. Geometric control of the ECs allowed mu and epsi to be tailored to the application. The magnetic metamaterial exhibited enhanced mu and epsi with acceptable loss-factor levels. Models for predicting mu and epsi are presented, the benefits of employing metamaterial substrates are discussed, and the results in this antenna experiment are presented. The metamaterial exhibits performance characteristics not achievable from natural materials. Of particular significance is that with the permeability varying strongly and predictably with frequency, the miniaturization factor may be selected by tuning the operating frequency. Simulations indicate that such performance can be extended to several gigahertz with current technology. Relative permeability values in the mur=1-5 range are achievable for moderately low-loss applications. Representative antenna miniaturization factors on the order of 4-7 over a moderate (approximately 10%) transmission bandwidth and efficiencies in a moderate range (20%-35%) are demonstrated with the possibility of higher efficiencies indicated

319 citations


Journal ArticleDOI
Abstract: Wideband planar monopole antennas with dual band-notched characteristics are presented. The proposed antenna consists of a wideband planar monopole antenna and the multiple cup-, cap-, and inverted L-shaped slots, producing band-notched characteristics. In order to generate dual band-notched characteristic, we propose nine types of planar monopole antennas, which have two or three cap (cup or inverted L)-shaped slots in the radiator. This technique is suitable for creating ultra-wideband antenna with narrow frequency notches or for creating multiband antennas

303 citations


Journal ArticleDOI
Abstract: In this paper, a Wilkinson power divider operating at two arbitrary different frequencies is presented. The structure of this power divider and the formulas used to determine the design parameters have been given. Experimental results show that all the features of a conventional Wilkinson power divider, such as an equal power split, impedance matching at all ports, and a good isolation between the two output ports can be fulfilled at two arbitrary given frequencies simultaneously

295 citations


Journal ArticleDOI
Abstract: In this paper, a new methodology for the design of compact planar filters in microstrip technology is proposed. This is based on cascading filter stages consisting of the combination of complementary split-ring resonators (CSRRs), recently proposed by the authors, series capacitive gaps, and grounded stubs. By this means, we achieve the necessary flexibility to simultaneously obtain quite symmetric frequency responses, controllable bandwidths, and compact dimensions. Two prototype device bandpass filters are provided to illustrate the potentiality of the proposed approach. In the first prototype, the structure is periodic (i.e., composed of identical cells) and behaves as a left-handed transmission line with controllable bandwidth. In the second prototype device, periodicity is sacrificed with an eye toward the synthesis of a standard (Chebyshev) approximation. The measured frequency responses point out low insertion losses in the passband, as well as high-frequency selectivity with small dimensions. As compared to conventional parallel coupled line filters, reduction of device length by a factor of 2.4 is demonstrated. This is the first time that planar filters with controllable bandwidth based on CSRRs are achieved. These structures can be of interest in those applications where miniaturization and compatibility with planar circuit technology are key issues

Journal ArticleDOI
Abstract: A novel method for designing multiband bandpass filters has been proposed in this paper. Coupling structures with both Chebyshev and quasi-elliptic frequency responses are presented to achieve dual- and triple-band characteristics without a significant increase in circuit size. The design concept is to add some extra coupled resonator sections in a single-circuit filter to increase the degrees of freedom in extracting coupling coefficients of a multiband filter and, therefore, the filter is capable of realizing the specifications of coupling coefficients at all passbands. To verify the presented concept, four experimental examples of filters with a dual-band Chebyshev, triple-band Chebyshev, dual-band quasi-elliptic, and triple-band quasi-elliptic response have been designed and fabricated with microstrip technology. The measured results are in good agreement with the full-wave simulation results

Journal ArticleDOI
Abstract: A 120-GHz-band wireless link that uses millimeter-wave (MMW) photonic techniques was developed. The output power and noise characteristics of 120-GHz-band MMWs generated by converting a 125-GHz optical subcarrier signal were evaluated. It was then shown that the noise characteristics of the 125-GHz signal generated with these photonic technologies is sufficient for 10-Gb/s data transmission. We constructed a compact 120-GHz-band wireless link system, and evaluated its data transmission characteristics. This system achieved error-free transmission of OC-192 and 10-GbE signals over a distance of more than 200 m with a received power of below -30 dBm.

Journal ArticleDOI
TL;DR: A comprehensive approach to engineering design optimization exploiting space mapping (SM) using a new generalization of implicit SM to minimize the misalignment between the coarse and fine models of the optimized object over a region of interest.
Abstract: This paper presents a comprehensive approach to engineering design optimization exploiting space mapping (SM). The algorithms employ input SM and a new generalization of implicit SM to minimize the misalignment between the coarse and fine models of the optimized object over a region of interest. Output SM ensures the matching of responses and first-order derivatives between the mapped coarse model and the fine model at the current iteration point in the optimization process. We provide theoretical results that show the importance of the explicit use of sensitivity information to the convergence properties of our family of algorithms. Our algorithm is demonstrated on the optimization of a microstrip bandpass filter, a bandpass filter with double-coupled resonators, and a seven-section impedance transformer. We describe the novel user-oriented software package SMF that implements the new family of SM optimization algorithms

Journal ArticleDOI
TL;DR: It is found that components diffracting around the body are well modeled using correlated log normal variables, and a Nakagami-m distribution can be used to incorporate the influence of arm motions.
Abstract: Body worn wireless sensors for monitoring health information is a promising new application. In developing these sensors, a communication channel model is essential. However, there are currently few measurements or models describing propagation around the body. To address this problem, we have measured electromagnetic waves near the torso and derived relevant statistics. We find that components diffracting around the body are well modeled using correlated log normal variables, and a Nakagami-m distribution can be used to incorporate the influence of arm motions. We have implement this model and evaluated it in terms of important communication metrics. This paper describes body area propagation statistics and proposes a suitable computer model implementation.

Journal ArticleDOI
Abstract: This paper reports a new circularly polarized rectenna whose rectifying circuit includes two diodes. The rectenna consists of a coplanar stripline (CPS) truncated patch antenna and CPS bandpass filter, which can block harmonic signals up to the third order reradiating from the rectifying circuit. The rectenna is printed on Rogers Duroid 5880 substrate with /spl epsiv//sub r/=2.2 and a thickness of 20 mil. The new dual-diode rectenna can provide at least twice the dc output voltage than the traditional rectenna with only a single diode, which has the same layout dimension as the single-diode rectenna. The dual-diode rectenna achieves an RF-to-dc conversion efficiency of 76% at 5.8 GHz. The proposed rectennas can be interconnected to form the rectenna arrays by series, parallel, and cascaded connections. It is found that a cascade connected rectenna array can provide the highest output voltage. The antenna element can be easily extended to become a traveling-wave antenna or array suitable for high output voltage or current in wireless power transmission applications.

Journal ArticleDOI
TL;DR: A Ka-band transceiver using low-power double-sideband transmission to detect human heartbeat and respiration signals is demonstrated, and the detection accuracy is significantly improved with low transmitted power.
Abstract: A Ka-band transceiver using low-power double-sideband transmission to detect human heartbeat and respiration signals is demonstrated. The Ka-band electromagnetic wave offers higher detection sensitivity on small movement due to its shorter wavelength. Indirect-conversion receiver architecture is chosen to reduce the dc offset and 1/f noise that can degrade the signal-to-noise ratio and detection accuracy. Furthermore, the double-sideband signals at the transmitter output can be in quadrature by choosing a proper frequency separation to relieve the severe null point problem that occurs at high frequency. As a result,the detection accuracy is significantly improved with low transmitted power. This radar sensor system achieves better than 80% detection accuracy at a distance of 2.0 m with a combined transmitted power of only 12.5 /spl mu/W in both sidebands.

Journal ArticleDOI
Abstract: High isolation and compact size microstrip diplexers designed with common resonator sections have been proposed. By exploiting the variable frequency response of the stepped-impedance resonator, resonators can be shared by the two filter channels of the desired diplexer if their fundamental and the first spurious resonant frequency are properly assigned. Size reduction are, therefore, achieved by introducing a few common resonator sections in the circuit. This concept has been verified by the experimental results of two diplexer circuits. One of the diplexers is composed of two three-pole parallel-coupled bandpass filters and the other is composed of two four-pole cross-coupled bandpass filters, which are formed by only five and six resonators, respectively. Both of them occupy extremely small areas while still keeping good isolations. Good agreements are also achieved between measurement and simulation.

Journal ArticleDOI
Abstract: A microstrip bandpass filter using stepped-impedance resonators is designed in low-temperature co-fired ceramic technology for dual-band applications at 2.4 and 5.2 GHz. New coupling schemes are proposed to replace the normal counterparts. It is found that the new coupling scheme for the interstages can enhance the layout compactness of the bandpass filter; while the new coupling scheme at the input and output can improve the performance of the bandpass filter. To validate the design and analysis, a prototype of the bandpass filter was fabricated and measured. It is shown that the measured and simulated performances are in good agreement. The prototype of the bandpass filter achieved insertion loss of 1.25 and 1.87 dB, S11 of -29 and -40 dB, and bandwidth of 21% and 12.7% at 2.4 and 5.2 GHz, respectively. The bandpass filter is further studied for a single-package solution of dual-band radio transceivers. The bandpass filter is, therefore, integrated into a ceramic ball grid array package. The integration is analyzed with an emphasis on the connection of the bandpass filter to the antenna and to the transceiver die

Journal ArticleDOI
Abstract: This paper presents analytic and experimental comparisons for high-efficiency class-F and inverse class-F amplifiers. The analytic formula of the efficiencies, output powers, dc power dissipations, and fundamental load impedances of both amplifiers are derived from the ideal current and voltage waveforms. Based on the formula, the performances are compared with a reasonable condition: fundamental output power levels of class-F and inverse class-F amplifiers are conditioned to be identical. The results show that the inverse class-F amplifier has better efficiency than that of class-F amplifiers as the on-resistance of the transistor increases. For experimental comparison, we have designed and implemented the class-F and inverse class-F amplifiers at I-GHz band using a GaAs MESFET and analyzed the measured performances. Experimental results shows 10% higher power-added efficiency of the inverse class-F amplifier than that of the class-F amplifier, which verifies the waveform analysis.

Journal ArticleDOI
Abstract: A novel approach for the generation of high-frequency microwave signals using a dual-wavelength single-longitudinal-mode fiber ring laser is proposed and demonstrated. In the proposed configuration, a dual-wavelength fiber Bragg grating (FBG) with two ultranarrow transmission bands in combination with a regular FBG is used to ensure single-longitudinal-mode operation of the fiber ring laser. A semiconductor optical amplifier is employed as the gain medium in the ring cavity. Since the two lasing wavelengths share the same gain cavity, the relative phase fluctuations between the two wavelengths are low and can be used to generate a low-phase-noise microwave signal without need of a microwave reference source. Three dual-wavelength ultranarrow transmission-band FBGs with wavelength spacing of 0.148, 0.33, and 0.053 nm are respectively incorporated into the laser. Microwave signals at 18.68, 40.95, and 6.95 GHz are obtained by beating the dual wavelengths at a photodetector. The spectral width of the generated microwave signals as small as 80 kHz with a frequency stability better than 1 MHz in the free-running mode at room temperature is obtained.

Journal ArticleDOI
Abstract: The concept of the conventional coupling matrix is extended to include designs of dual- and triple-band filters. The multiband response is created by either placing transmission zeros within the bandwidth of a wideband filter or using higher order resonances. Realizable topologies both in planar and waveguide technologies can be imposed and associated coupling coefficients enforced during optimization. The design process is verified by measurements and comparison with results of commercially available field solvers

Journal ArticleDOI
Abstract: A low insertion-loss single-pole double-throw switch in a standard 0.18-/spl mu/m complementary metal-oxide semiconductor (CMOS) process was developed for 2.4- and 5.8-GHz wireless local area network applications. In order to increase the P/sub 1dB/, the body-floating circuit topology is implemented. A nonlinear CMOS model to predict the switch power performance is also developed. The series-shunt switch achieves a measured P/sub 1dB/ of 21.3 dBm, an insertion loss of 0.7 dB, and an isolation of 35 dB at 2.4 GHz, while at 5.8 GHz, the switch attains a measured P/sub 1dB/ of 20 dBm, an insertion loss of 1.1 dB, and an isolation of 27 dB. The effective chip size is only 0.03 mm/sup 2/. The measured data agree with the simulation results well, including the power-handling capability. To our knowledge, this study presents low insertion loss, high isolation, and good power performance with the smallest chip size among the previously reported 2.4- and 5.8-GHz CMOS switches.

Journal ArticleDOI
Abstract: We present a computational study comparing the performance of narrowband (NB) microwave hyperthermia for breast cancer treatment with a recently proposed ultra-wideband (UWB) approach. Space-time beamforming is used to preprocess input signals from both UWB and NB sources. The train of UWB pulses or the NB sinusoidal signals are then transmitted simultaneously from multiple antennas into the breast. Performance is evaluated using finite-difference time-domain electromagnetic (EM) and thermal simulations with realistic numerical breast phantoms derived from magnetic resonance images (MRIs) of the breast. We use three methods of mapping MRI data to complex permittivity data to account for uncertainty in the embodiment of the dielectric properties transitions in heterogeneous breast tissue. EM power-density deposition profiles and temperature profiles are compared for the UWB and NB cases in the three different breast phantoms. Dominant mechanisms that influence the efficacy of focusing UWB and NB signals in the breast are identified. The results of this study suggest that, while NB focusing performs reasonably well when the excitation frequency is optimized, UWB focusing consistently performs better, offering the potential for tighter focusing and greater reduction of hot spots, particularly in breast tissue, which exhibits distinct dielectric-properties boundaries within the tissue heterogeneity.

Journal ArticleDOI
Abstract: In this paper, we present a new shielding and absorbing composite based on carbon nanotubes (CNTs) dispersed inside a polymer dielectric material. The extremely high aspect ratio of CNTs and their remarkable conductive properties lead to good absorbing properties with very low concentrations. A broadband characterization technique is used to measure the microwave electrical properties of CNT composites. It is shown that a conduction level of 1 S/m is reached for only 0.35 wt % of a CNT, while, for a classical absorbing composite based on carbon black, 20% concentration is mandatory. The conductive properties are explained by a phenomenological electrical model and successfully correlated with rheological data aiming at monitoring the dispersion of conductive inclusions in polymer matrices

Journal ArticleDOI
Abstract: In this paper, we investigate the optimum carrier-to-sideband ratio (CSR) for maximizing the transmission performance of an optically modulated millimeter-wave signal in a fiber-wireless system via experiment, theory, and simulation. We present a simple analytical model to assess the performance enhancement resulting from optical CSR variations. The model is capable of analyzing systems incorporating binary phase-shift keyed and quaternary phase-shift keyed modulation formats. We quantify the optical CSR of a point-to-point fiber-radio link and establish that the performance of the fiber-wireless links can be significantly improved when the optical signal is transmitted at the optimum CSR of 0 dB. The analysis further shows that the optimum optical CSR is independent of transmission bit rates.

Journal ArticleDOI
Abstract: In this study, we have developed a hybrid sensitive rectenna (rectifier + antenna) system at 2.45 GHz. To achieve this system, we have first optimized and validated a zero-bias microwave sensitive rectifier using commercial Schottky diodes. We have then optimized and achieved a 2times2 patch antenna array, which is associated to the microwave rectifier in order to validate the rectenna system, where an RF-dc conversion efficiency of 56% has been observed experimentally. In order to minimize the rectenna dimensions, we have conducted a study using the OMMIC ED02AH 0.20-mum GaAs pseudomorphic high electron-mobility transistor process to develop and achieve a monolithic rectifier at 2.45 GHz with RF-dc conversion efficiency of 65%

Journal ArticleDOI
Abstract: In this paper, we present a cost-effective chip-scale packaging solution for a 60-GHz industrial-scientific-medical band receiver (Rx) and transmitter (Tx) chipset capable of gigabit-per-second wireless communications. Envisioned applications of the packaged chipset include 1-3-Gb/s directional links using amplitude shift-keying or phase shift-keying modulation and 500-Mb/s-1-Gb/s omni-directional links using orthogonal frequency-division multiplexing modulation. This paper demonstrates the first fully package-integrated 60-GHz chipset including receive and transmit antennas in a cost-effective plastic package. A direct-chip-attach (DCA) and surface mountable land-grid-array (LGA) package technology is presented. The size of the DCA package is 7times11 mm2 and the LGA package size is 6times13 mm2. Optionally, the Tx and Rx chip can be packaged together with Tx and Rx antennas in a combined 13times13 mm2 LGA transceiver package

Journal ArticleDOI
Abstract: Novel slot-shaped defected ground structures (DGSs) on the microstrip line are presented to provide a band-rejection property with an improved Q factor. Two different geometries (U-slot and V-slot) are investigated. U-slot and V-slot DGSs have simple shapes compared to the conventional DGSs, however, they provide more steep rejection characteristics. The Q factor of the band-rejection property for the U-slot DGS increases when the distance between two slots in the U-shape decreases. Similarly, the V-slot DGS provides a higher Q characteristic when the slot angle is reduced. Two bandstop filters are designed and fabricated employing three cascaded U-slot DGSs and V-slot DGSs, respectively. Experimental result shows that the high-Q band-rejection filter with three U-slot DGSs provides Q of 38.6. A fabricated filter with three cascaded V-slot DGSs also rejects the signals at the frequencies from 3.5 to 4.3 GHz with more than 20-dB suppression

Journal ArticleDOI
Abstract: The dielectric parameters of the tissue simulating liquids to assess the exposure from mobile phones were determined in a previous study considering the tissue distribution of the exposed regions of the head using a planar layered model and the transmission-line method. Currently, the standards for the compliance testing of wireless devices are being extended to more general exposure situations. This paper uses the same methods considering different locations of the body and the respective variations of the tissue structures and dimensions. The analysis of tissue compositions shows a significant increase of 2.2-4.7 dB of the peak spatial specific absorption rate (SAR) in comparison to the values assessed with current standard liquids. This increase is due to standing-wave effects in tissues with low water content. For a certain distance between the antenna and the body (approximately /spl lambda//3 for a /spl lambda//2 dipole), these standing-wave effects dominate the coupling mechanism, leading to a higher average SAR in layered tissue. The observations were validated using finite-difference time-domain simulations of an anatomical high-resolution human model. Nevertheless, a sound conservative exposure assessment applying phantoms filled with homogeneous standardized liquids is possible if a distance and frequency-dependent scaling factor is applied.