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Folded-wire X antenna with two feed ports is introduced, which can operate like a half-wave dipole, or array of two crossed dipoles depending on whether one or two ports are fed. The low-profile location of 1.8-GHz X antenna in front of flat plate makes a compact reflector antenna with a good input match in about 5% frequency band, gain of 8.5–9.0 dBi, and big inter-port and cross-polar isolations. The applications may include earth and satellite communication systems with polarization diversity action. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1508–1512, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24371

A “thru-short” noise de-embedding method for MOSFETs is presented. The capability of the “thru-short” method has been validated through a comparison of measured and de-embedded noise parameters using different methods. It is shown that the “thru-short” method is reliable for on-wafer de-embedding of both S-parameters and noise parameters up to 18 GHz. Noise contributions from the parasitics due to the contact pads and interconnections surrounding the MOSFET can be determined and removed accurately. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1379–1382, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24330

The least squares solution for the entire small-signal equivalent circuit is itself a formidable task. In this paper, a systematic approach comprising the total and conventional least squares method in analytically obtaining the small-signal field-effect transistor (FET) parameters values is introduced. The proposed method eliminates the conventional ldquocold FETrdquo and ldquohot FETrdquo modeling constraints and allows an ease in inline process tracking.

This article presents a systematic design and measurement of narrow and wide bandpass filters at 77 GHz in a 0.18-μm CMOS technology. Various bandwidths from 10 to 50% are realized using a parallel coupled line topology in a thin film microstrip configuration. The relationship between the insertion loss and the 3-dB bandwidth of the filters is experimentally determined for this technology. The result is also compared with theoretical prediction. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2934–2937, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23854

This paper investigates the design and implementation of millimeter-wave narrow-bandpass filters in a standard 0.18- m CMOS technology. Filters with a measured 10% 3-dB bandwidth at 60 and 77 GHz are realized in a thin-film microstrip structure by using the lowest metallization layer as a ground plane. The impact of dissipation losses of the filters is also examined. It is found that the metallization losses in the coupled-line filter as well as the ground plane are the main reasons for the insertion loss.

The major computation cost of pseudo-spectral method comes from the evaluation of differentiation matrix multiplication. In the past, uniform or Chebyshev collocation points are used for sampling. The differentiation matrix multiplication was evaluated by fast Fourier transform (FFT) or fast cosine transform (FCT), in order to reduce the computation complexity from O(N2) to O(N log(N)). However, the intrinsic properties of FFT or FCT may cause the wraparound effect and Gibbs phenomenon. Moreover, FFT or FCT is not applicable to other collocation points such as Legendre and Hermite. In order to improve the accuracy and applicability of the pseudo-spectral method, the fast multipole method (FMM) is exploited to substitute the FFT or FCT. By making use of the similarity of the N-body problem and the collocation problem, a new FMM-based pseudo-spectral time domain method is developed in this paper.

A wide-slot waveguide antenna implemented on low-temperature cofired ceramic technology is presented. The overall antenna is excited by aperture coupling. The design is simulated and validated by experimental measurement. The measured result shows that a 10-dB return loss has been achieved across the bandwidth from 2.6 GHz to 12.8 GHz, thus amounting to 132.5%. The measured radiation pattern of the proposed antenna is also presented and discussed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2181–2184, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23613

In this article, a novel method to improve the rejection of edge coupled filters by perturbing the coupled line sections by a length, δ, is introduced. This gives controls over the null position between the fundamental and 1st harmonic of the filter which results in a steeper rejection slope by shifting this null closer to the centre frequency. A 4th order 5 GHz band-pass filter is designed and tested. Measured results show an improvement of about 9 dB at 6 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 680–683, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23176

This paper describes an innovative test strategy comprising a compliant elastomer mesh for testing fine pitch wafer-level package (WLP) devices. The test probe, hardware, and sample preparation processes are detailed. The components of the test hardware socket such as the SMA connectors, coplanar transmission lines on the PCB, via, off-chip interconnect, and elastomer mesh probe have been modeled. A complete system-level model, with off-chip interconnects on the WLP device pads, has been developed. The measurement and model demonstrate that the prototype test socket performs at 5 GHz with an insertion loss of about 3 dB. WLP device with Bed-of-Nail interconnects are characterized. Functional test features of the system are also addressed.

A novel tri-band electromagnetic bandgap (EBG) fed coplanar slot antenna is proposed and adopted for this investigation. With the integration of the EBG as an impedance matching element, a wider impedance bandwidth response is obtained for all the bands. Analytical expression for designing the coplanar EBG unit cells are derived for the first time. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 954–960, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22315

A novel ultra-wideband (UWB) stacked microstrip patch antenna suitable for UWB application is presented in this article. This compact and planar proposed antenna is found to have a very broad impedance bandwidth as compared to the conventional electromagnetic coupled antenna. The proposed antenna is able to achieve an impedance bandwidth of about 101.8% for VSWR less than 2, centred at around 7 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1659–1665, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22555

The adoption of flower rings coupled with inner split rings within an open-square-loop resonator for size miniaturization is first analyzed and designed. To demonstrate the proposed technique of loading, a novel dual-mode open-loop resonator operating at 2.5 GHz is next designed. The proposed technique of perturbation achieves a 48.4% loading factor for the resonators. The proposed resonator is 2.94% smaller in area as compared to the meander loop resonator, and 5.5% smaller in area as compared to the hairpin resonator. Harmonic suppression is also easily achieved through the integration of these circular rings.

A wideband dual mode bandpass filter at 9.0 GHz with a bandwidth of 20% has been demonstrated in low temperature cofired ceramics (LTCC). A new stacked-ring resonator (SRR) is proposed and its design methodology as well as analysis is presented in details. The simulated and measured results are in good agreement. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2246–2249, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21917

A novel multi-frequency transformer is developed based on the dual frequency transformer technique. The transmission line analysis shows that for a return loss of −10 dB, the three-pole transformer can achieve 160% bandwidth when compared with 60% of the dual frequency transformer. For verification, a novel UWB LTCC multilayer transition from CPW to microstrip is developed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 329–332, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22142

A novel electromagnetic-bandgap (EBG) in-phase hybrid-ring equal power divider is described. Coupled with the closed-form analytical expressions for the EBG structure, a systematic technique of design is presented for the first time. Compared to the conventional hybrid-ring equal power divider, based on the 15-dB return-loss criteria, an increase in both the input and output impedance bandwidth of approximately 10% from a starting frequency of 2.5 GHz, and a phase error of 0.006/spl deg/ within the passband have been achieved for the proposed structure. The proposed in-phase hybrid-ring equal power divider, besides providing a much broader bandwidth and occupying a smaller estate area, also possesses good harmonic suppression characteristic.

This paper presents an efficient simulation algorithm-Scattering matrix method for investigation of the coated finite two-dimensional electromagnetic bandgap (EBG) structures. The method is derived to be capable to simulate the band properties of the coated cylinder photonic crystal with wave discontinuities. Numbers of photonic crystals with waveguide discontinuities are examined. The transmission characteristics of the EBG embedded with metal, dielectric, and various coated cylinders are analyzed. The results show that the tuned bandgap properties are able to provide an additional possibility to develop a novel device.

Research studies of symmetrical spiral inductors for silicon technology have become very important and challenging. In this article, we attempt to give a detailed explanation of how symmetrical spiral inductors help to improve the quality factor (Q) as compared to conventional nonsymmetrical inductors. The experimental results are presented to verify our theory. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.

A miniaturized dual-mode ring bandpass filter at 1.45 GHz with a bandwidth of 6% is demonstrated. The perturbation of the dual modes is realized by a pair of local ground defects. The miniaturization is achieved by loading the peripheral of the ring with the butterfly radial stub structure. A 41% loading factor has been achieved using this method. The simulated and measured results are in good agreement.

A wideband pentagon-slot microstrip antenna with a semicircle probe feed is proposed. The broadband characteristic is achieved by cutting a pentagon slot at each corners of the patch. The proposed antenna is able to achieve an impedance bandwidth of 68.3% for a VSWR of less than 2. Experimental comparison with a similar-size retangular microstrip patch antenna has also been conducted in this paper. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 500–505, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21211

In this paper, we describe a novel method for modeling pad geometries via parameter extraction using S-parameter measurements. We apply the method to a square pad structure, built with a coplanar transmission line on high-resistivity silicon, and arrive at an equivalent-circuit model that represents the pad over a wide operating frequency range of 1 to 20 GHz. Two-port ABCD matrices of two transmission lines of different lengths are used to derive the model. The model is optimized and validated using circuit simulation by comparing the simulated results with those of the measurements. This method is significant for high-frequency modeling of fine-pitch wafer-level package off-chip interconnects. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 115–118, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20740

The design and measured results of a rectangular U-slot patch antenna proximity fed by a double-/spl Pi/ stub feed are described. Using approximately 0.09/spl lambda/ of air gap separating the upper and lower dielectric, an impedance bandwidth of 26% centered at 4.4 GHz and a gain of 6 dBi have been achieved. The proposed antenna is noted to be tolerable to lateral displacement of the feed and produces a better impedance matching than the single /spl Pi/-stub antenna. The radiation patterns obtained are stable across the passband.

A modified contour integral method coupled with segmentation method has been used, for the first time, to analyze both the Sierpinski fractal carpet (SFC) antennas of different orders and an SFC antenna with electromagnetic band gap (EBG) ground plane. The close agreement between the calculated and measured results for resonant frequencies and input return losses indicates that this technique can be used to accurately predict the impedance characteristic. A novel stacked microstrip Sierpinski carpet fractal antenna using the EBG ground plane is also presented. Comparing to an ordinary microstrip fractal antenna, which has a maximum bandwidth of approximately 2%, the proposed antenna has a higher input impedance bandwidth of nearly 9%. The radiation patterns of the proposed antenna are improved due to the removal of unwanted radiation caused by the surface wave. The experimental measurement results of the proposed antenna are presented in this paper.

Detailed experimental investigations described here show the overall characteristics of on-chip inductor and capacitor serial interconnects (L--Cs) on silicon substrates. Using a new equivalent circuit model and the measured S parameters obtained by deembedding techniques, we examine and compare a single inductor, single capacitor, and two sets of series L--Cs. Agreement between the measured and simulated S parameters is excellent. At low frequency, the first resonant frequency f/sub res/ of series L--Cs can be easily determined by f/sub res/=(2/spl pi//spl radic/(LC))/sup -1/, while at high frequency, parasitic parameter effects of both the substrate and the metal strips on f/sub res/ of the L--Cs circuit must be considered.

A novel course conducted for the past three years at the National University of Singapore is described. The course design projects introduce students to microwave monolithic integrated circuit (MMIC) component and subsystem design and expose them to modern computer-aided design (CAD) tools, industry standard test equipment, and procedures. In addition, since the proposed topics are industry-collaborated research projects, students gain new enthusiasm for the circuit design and directly see the importance and relevance in the engineering field. In contrast to the available MMIC courses conducted in the other universities or organizations, these students are given the complete freedom to implement the hardware within a fixed time frame. Implementation of these MMIC circuitries using external foundries, such as United Monolithic Semi-conductor (UMS), Philips Microwave Limeil (PML), and Triquint, has proven to be highly motivational and educational and, eventually, has led to increased enrollments in other higher level electromagnetic and microwave circuit modules.

Two efficient methods of inductance calculations for spiral inductor with special emphasis on nonuniform current distribution on the metallic trace are presented. Based on the conventional magnetic-flux method and the energy method, a unified approach for modeling the eddy current and skin depth of the spiral inductor has been presented. Our proposed method is validated with experimental results, and good agreement is obtained. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 432–436, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11402

This paper presents a novel approach to alternate the electromagnetic properties of the electromagnetic band gap (EBG), where a ferrite defect is introduced, and in addition, a DC magnetic field is applied to alternate the EBG's electromagnetic property. Numerous devices are examined, including a coupler and a Y-branch filter. The numerical experiments demonstrate that the devices electromagnetic characteristics can be easily adjusted by varying the DC magnetic-field intensity. In this paper, the examinations are performed using the scattering-matrix method. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 395–400, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20481

An efficient approach for fast evaluation of the poles' locations in two-layered microstrip geometry has been presented. For the first time, good initial values and functional expressions with quadratic convergence for two-layered pole extraction have been derived. Numerical comparison with available methods of extraction shows that our proposed method is very accurate and extremely fast in convergence. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 253–258, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20109

A dual-mode ring bandpass filter with two pairs of capacitors has been designed. The capacitors are used to control the location of the even- and odd-mode frequencies independently, allowing weak coupling for narrow-band filter design with realizable capacitance values. Theoretical expressions have been derived for these frequencies. A 4% bandwidth bandpass filter centered at 1.9 GHz was designed and tested with good agreement between theoretical and measured results.

A simple, robust, accurate method to extract the thermal resistance of BJT/HBT devices is proposed, which only needs the measured device DC I-V characteristics at room temperature. No optimization is needed to extract the thermal resistance. The proposed method is verified using a variety of BJT/HBT devices. Compared to the measured results taken from both CW DC measurements and isothermal measurements, the extracted values using our method is in excellent agreement with the conventional method. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 499–502, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10648

A unique and simple method of modeling a coplanar waveguide meander-line inductor is presented. Using only the lower frequency response of electrically smaller inductors, their higher frequency response is predicted. In addition, the responses of physically larger inductors can also be made using circuit models synthesized directly from the unit cell layout of the inductors. The modeling and prediction results for an ideal metal and lossless substrate is presented, together with comparisons made for various lossy parameters. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12, 520–529, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mmce.10052

A novel broadband stacked E-shaped patch antenna is proposed in this paper. The proposed antenna has an input impedance bandwidth of about 38.41%, better than the conventional E-shaped microstrip patch antenna, which has an input impedance bandwidth of 33.8%. Through the use of the washer on the probe of the stacked patch antenna, the input impedance bandwidth is improved further to 44.9%. The radiation patterns are found to be relatively constant throughout the whole band. Comparisons of these antennas are presented in this paper.

Based on an earlier study by Kuhn and Ibrahim (see IEEE J. Trans. Microwave Theory Tech., vol. 49, no. 1, p. 31-38, 2001) on current crowding, an improved expression incorporating the skin effect for the prediction of series resistance in spiral inductor modeling has been derived. A modified model for the spiral inductor, which accounts for the eddy-current effect, is thus proposed. Relatively good agreements between the measured data and the results generated from the model are obtained.

A broad-banding technique for in-phase equal power divider is described. Detailed comparisons between the proposed variants of power dividers and the conventional in-phase power divider are also performed. Based on the 15-dB input and output return losses criteria, it is noted that a maximum impedance bandwidth of 44.3% for an amplitude error of /spl plusmn/0.9 dB and a phase error of /spl plusmn/1.8/spl deg/ can be achieved, for the first time, for divider with length more than 3/spl lambda//2 ring impedance transformer. A systematic design technique that relaxes some of the conventional constraint in in-phase hybrid ring equal power divider design, is also described.

A simple and efficient way of extracting the small-signal model parameters of the heterojunction bipolar transistor (HBT) is proposed. This novel approach provides a new insight into the strong correlation between the extrinsic and intrinsic HBT model parameters and raises the optimization efficiency by drastically reducing the search space. For the first time in HBT modeling, an explicit equation on the total extrinsic elements is derived, which results in a reduction of the number of optimization variables. The simulation results are presented and it is shown that this new method can yield a good fit between measured and simulated S parameters. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 311–319, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mmce.10001

The conventional approach for modeling the dc I-V characteristics of a MESFET transistor usually adopts the hyperbolic tangent dependence on V/sub ds/. On the contrary, our new empirical model describes the device drain current as a polynomial of effective gate-source voltage V/sub eff/. The derived model is capable of accurately modelling the subthreshold effect and the device current-voltage behavior at different operating regions, in particular, the device operation around the pinchoff region. Measured and modeled results of a 0.5-/spl mu/m gatelength MESFET device are compared and good agreement has been obtained. Comparisons between the proposed model, Curtice model, Chalmers model, and Parker model are also made in this paper. In addition, a single-stage class-AB amplifier was built with a commercial high-power MESFET transistor to verify the new model.

A new parameter extraction methodology — local ratio evaluation is presented which is well suitable for converting one model to another. An example is given for VBIC model extraction by going through SPICE Gummel–Poon (SGP) model. It is based on the fact that VBIC model is a direct enhancement and extension of SGP model. First, the standard SGP model is extracted in the standard way. Next, SGP model parameters are directly converted to those in VBIC model. Local modifications are subsequently carried out for those parameters that are affected by different equations used in the two models. Finally, new model parameters for enhanced modeling features are introduced by evaluating the difference between measurement and simulation.

In order to obtain accurate closed-form representations of the microstrip Green's functions, it is often necessary to find the locations of the proper and improper surface-wave poles. In this paper, we present an efficient and robust iterative algorithm based on contraction mapping, which can locate all the proper and improper solutions of the characteristic equations of the grounded dielectric slab. The dielectric may also be lossy.

An efficient technique of extracting the small-signal model parameters of the heterojunction bipolar transistor (HBT) is proposed in this paper. The relation between the extrinsic and intrinsic model parameters, which can be employed to drastically reduce the search space, is studied in depth. For the first time, the HBT transistor is characterized by describing S-parameters with a set of complex exponentials using the generalized pencil-of-function method. The reliable initial values of some extrinsic elements can be determined from the set of complex exponentials. This novel approach can yield a good fit between measured and simulated S-parameters.

In this paper, the Sonie-Schafheitlin integration formula and the sampling theorem are integrated into the conventional spectral-domain method to form an efficient and fast convergent hybrid method. As a simple demonstration of the method, the novel technique is applied to the microstrip dispersion problem. The incorporation of the Sonie-Schafheitlin integration formula and the sampling theorem aid to accelerate the convergence of the Sommerfeld integral. Good agreement between the simulated results and the conventional method are obtained.

of ON too. The basis of the FMM is the application of the addition theorem to the free-space Green's function 1 . Coifman, Rokhlin, and Wandzura 2 , Song and Chew 3 , and Sertel and Volakis 10 have discussed how to choose the multipole expansion orders for achieving high accuracy in the FMM. The accuracy of the multipole expansion of the scalar Green's function directly affects the FMM acceleration schemes. This thus shows the motivation of this paper, that is, to address the accuracy of addition theorems for the free- space scalar Green's function and the convergence of the FMM algorithms.