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

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 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.

Uniplanar one‐dimensional EBG with a periodic butterfly‐radial slot (BRS) structure has been proposed for wide spurious filtering. An optimum design ratio and parameters have been characterized for this particular BRS‐CPW EBG configuration. Two six‐cell BRS‐CPW EBG low‐pass filters are designed and they demonstrate a wide bandwidth rejection of more than 86% up to the 3rd harmonic. The experimental and simulated results are in good agreement. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 320–323, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20130

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.

Recently, Teo et aL proposed a discrete complex image method that is able to represent both the near and far fields of the Green's function accurately, using only a single approximate Green's function. In this paper, an error analysis of this method is presented. The error analysis shows an additional term, which represents the quasi-static image of the surface-wave poles plays a crucial role in the convergence and accuracy of this new method. As the extraction of poles is required, a recently proposed algorithm by Teo et aL is also discussed and compared with existing methods in terms of computational speed.

Careful design of via transitions intended for use in practical microwave applications is needed to realize the advantages of low‐temperature co‐fired ceramic (LTCC), such as highly integrated buried passive circuits. Grounded coplanar waveguide (GCPW) to asymmetrical stripline vertical interconnects is optimized for thick LTCC substrate. The focus is to develop a vertical transition through thick substrate supporting deep embedded interconnects (DEI). The measured results demonstrate vertical transitions with good performance up to 20 GHz. Embedded LTCC bandpass filter with such vertical transition has been demonstrated with an insertion loss of 2.2 dB and return loss better than −20 dB at 16.2 GHz. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 179–181, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11007

A new and efficient scheme for adaptive integral method is presented for solving the RCS of large scattering objects. Interlaced grid system is introduced to reduce the memory requirement for the FFT calculation. The total memory resource required for FFT calculation of the new scheme is approximately 5.6 times less than the conventional AIM method. Interactions between the different grid systems are obtained by using interpolation. It is proven that the complexity of the newly proposed scheme is same as the conventional AIM.

A new Butterfly-Radial Slot (BRS) structure has been proposed for broadband PBG applications. The BRS assisted PBG demonstrates broad bandwidth of over 70% and rejection of at least 40 dB in the band of interest. A design ratio has been derived and five sets of PBG structures have been designed, simulated and fabricated. Experimental and simulated results are in good agreement.

Circular holes are etched off a microstrip disk resonator. This results in a size reduction of 30%. By offsetting the positions of some of these holes, a degenerate orthogonal mode is excited, resulting in a split-mode bandpass filter. This filter can be considered as a lattice-type structure. A filter with a bandwidth of 8% centered at 2.0 GHz was designed. The measured insertion loss is 0.6 dB.

New microstrip slow‐wave bandpass filters using open‐loop resonator loaded with inter‐digital capacitive fingers is proposed. The filter features not only compact in size, but also exhibits spurious stop‐band rejection. Filters of this type with elliptic function and Chebyshev response are demonstrated. There is good agreement between experimental and full‐wave electromagnetic (EM) simulation results. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 157–159, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10545

In order to obtain accurate closed-form representa- tions 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 characteristics equations of the grounded dielectric slab. The dielectric may also be lossy. Index Terms—Contraction mapping, Green's function, grounded dielectric slab, improper poles, iterative procedure, microstrip problems, poles and zeros, proper poles, surface-wave poles.

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.

A new method for the design of the Marchand balun using microstrip lines is proposed. This new method cuts down significantly on the time required to design a balun. A 1-6 GHz Marchand balun was designed using this method and fabricated Measured and fabricated results show a good match. A bandwidth of 1.5-5.5 GHz was obtained with a phase imbalance of less than 5 degrees.

A new class of compact microstrip filter loaded with a low-characteristic impedance triangular stub is introduced. The respective filter upper stopband selectivity is improved. Without the presence of cross-coupling between non-adjacent resonators, one transmission zero is observed. Frequency tuning can easily be achieved by adjusting the reactance of the stub.

Photonic bandgap structure is used as a design parameter for the fundamental passband in a split-mode microstrip square resonator. A defect in the PBG cells under the resonator, allows coupling between the two degenerate modes. A filter is designed at 2.2 GHz with good agreement between simulated and measured results.

In this paper, a full wave partial element equivalent circuit (PEEC) technique using exact Green's function is introduced for the parameter extraction of a passive device in a homogeneous media over a wide frequency range from de to a frequency of interest. This technique makes use of some analytical techniques and cartesian multipole expansion to derive simple closed form expressions for each individual element of the coupling matrices that commonly arise in integral equation algorithms, in terms of the wave number alone, Hence, these matrices can be reused each time a new frequency is selected. As simple closed form expressions are used, very fast computation is possible.

Both electrical and mechanical models, exemplified with a micromachined capacitive switch with simple bridge structure, accurately describing its electrical and mechanical characteristics are described in this paper. The electrical model is represented as a RLC circuit, while the mechanical model is represented as a fixed-fixed beam. The advantage of these models is that it is possible to pre-determine various characteristics. such as the switching time of micromachined capacitive switches, during the design stage. These models can be used to accurately design micromachined capacitive switches for microwave applications. An illustrated fabrication process is also discussed.

This work presents an application of the FD-TD method in simulating electromagnetic fields and analyzing a planar microstrip filter. The frequency dependent characteristics of the microstrip filter are derived from the full-wave analysis in the time domain. The motivation of this paper is to establish the validity of the F'D-TD method in modeling circuit components for MMIC CAD applications. The numerical results are compared to these existing predicted results as well as measurement data. A very good agreement is thus obtained from the comparison. It is, however, realized that with the implementation of the recent Berenger's Perfectly Matched Layer (PML) as an excellent absorbing wall, the computational speed for a given accuracy is much faster than the previous calculation in the filter analysis.

This article presents two fabricated 0.25 mu m first-pass pHEMT wideband MMIC low noise amplifiers (LNA) covering 1 to 8 GHz and 5 to 20 GHz, respectively. Wideband MMIC LNAs are usually designed with the emphasis on noise figure, which sacrifices the input and output (I/O) SWR. A balance configuration is used to improve the SWR, increasing real estate and complexity. A design to simultaneously achieve low noise, good input SWR across the bandwidth and high gain greater than 20 dB in a single chip solution without using balance topology was achieved. The LNAs' measured performance agreed with prediction. These MMIC LNAs have the best combination of noise figure, I/O SWR, high gain, wide bandwidth and P1dB. The noise figures of the 1 to 8 GHz and 5 to 20 GHz amplifiers are less than 2.6 dB, with I/O SWR less than 2.2.