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A new scheme with an interdigital line and a defected ground structure for dual-band operation is dealt with in this letter. The proposed structure is analyzed using a series L-C resonator model added a parasitic shunt capacitance. The nonlinear phase of this structure is dependent on the dumbbell size of the defected ground. This proposed scheme is applicable for a short-ended stub circuit and a dual pass-band filter at the centre frequencies of 860 and 1810 MHz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1353–1356, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24331 [ABSTRACT FROM AUTHOR]

In this paper, we describe a fixed-beam broadband planar antenna array at millimeter-wave frequencies. The antenna is fed by waveguide-feed and microstrip-feed networks. In order to ensure fixed beams and a broad bandwidth, a subarray concept is introduced. For efficient coupling, a novel waveguide-to-slot transition consisting of a slot pair and a narrow conductive bar is proposed. Simulated and measured bandwidth is found to be more than 7.1% from 40.5–43.5 GHz. The main beam directions are broadside over all frequencies. The maximum measured antenna gain is 30.2 dBi at 42.0 GHz. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 283–287, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20279 [ABSTRACT FROM AUTHOR]

In this paper, new feeding structures with strong coupling using linearly and exponentially tapered lines are proposed in order to overcome the design problems due to coupling losses and impedance mismatching. The tapered feedlines are characterized for the optimum feedline length of λg/2 and insertion losses (ILs) and fractional bandwidths (FBWs) with respect to the feeding angle. The proposed structures have been applied to BPFs and patch antennas. The experimental results show lower insertion losses and better matching properties, compared with circuits with conventional feedlines. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 505–508, 2003 [ABSTRACT FROM AUTHOR]

In this paper, a new bandpass filter inserting a microstrip-line resonator between two ring dielectric resonators is described in an MIC environment. This filter is designed using the general filter design technique, and is analyzed using the FDTD method. The designed result shows good agreement with the experimental and simulated ones. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 319–322, 2001. [ABSTRACT FROM AUTHOR]

In this letter, a compact low-pass filter (LPF) with wideband rejection using double-step impedance shunt stub (SISS) and barbell-type defected ground structure (DGS) is presented. This proposed LPF has similar characteristics in bandwidth, but good wideband rejection and cutoff sharpness compared with the same size conventional LPF, using SISS and conventional DGS. The size reduction of the proposed LPF is about 23% more than the conventional one. Good agreements are achieved between the simulated and measured results. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 132–134, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24883 [ABSTRACT FROM AUTHOR]

In this letter, a new bandpass filter (BPF) with coplanar waveguide using interdigital capacitor and interdigital defected ground structure is proposed. The proposed BPF size is reduced about 33% compared to the BPF using a conventional DGS one. Both filters have lower and higher cutoff frequency at about 1.4 and 2.4 GHz. The measured results are well agreed with the simulation ones. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2915–2917, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24804 [ABSTRACT FROM AUTHOR]

A compact coplanar waveguide (CPW)-fed monopole antenna is proposed for dual-band wireless local area network (WLAN) applications. The proposed antenna, which consists of a meander strip and a L-shaped strip, has compact size of 20 mm × 17 mm × 1.6 mm including the ground. The impedance bandwidth with 10 dB return loss is about 330 MHz (2.3–2.63 GHz) for 2.4 GHz band and 950 MHz (4.93–5.88 GHz) for 5 GHz band. The measured peak gains are 1.7 dBi at lower and 2.8 dBi at higher band, respectively. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3147–3149, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23914 [ABSTRACT FROM AUTHOR]

A coplanar waveguide (CPW)-fed ultra-wideband staircase monopole antenna with a frequency-notch characteristic is presented. The proposed antenna consists of a planar four-step staircase rectangular monopole with a ground short-circuited stub, open stubs at the ground part, and two-step impedance transformer at the CPW-fed line. The impedance bandwidth is increased due to an offset feeding technique and one-side ground notch. The notched frequency band can be accomplished by means of the method that involves adding open stubs at the ground. The measured results are in good agreement with the simulated ones. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2545–2547, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22775 [ABSTRACT FROM AUTHOR]

In this paper, a design technique that includes a synthesis procedure and a realization method for a microstrip open-loop resonator filter with two passbands is described. Transmission zeros of the filter-transfer function are employed to split a single passband into two passbands, and the filter-coupling structure used to realize two passbands is also given. The measured result shows good agreement with the synthesized one. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 241–243, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20956 [ABSTRACT FROM AUTHOR]

In this paper, a compact planar microwave duplexer on a high-dielectric substrate is proposed. As Ba(Mg1/3Ta2/3)O3 (BMT) has good dielectric performances with a high-dielectric constant of ℇr = 23, it is suitable for application on printed circuit boards for compact-size circuits. The BMT substrate is fabricated using a tape-casting process; then, metal patterns are screen-printed upon it and silver pasted. An open-loop ring-type duplexer is designed and implemented on the BMT substrate. A size reduction of about 80% is achieved without any degrading duplexer performances, compared with the same one fabricated on a commercial substrate (ℇr = 6.15). © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 251–253, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20108 [ABSTRACT FROM AUTHOR]

This paper presents two types of phase shifters using parallel coupled lines as compact and broadband couplers. Phase shifts are enabled by varying the varactor capacitances or by switching the PIN diode ON/OFF. Both have shown about 40% bandwidth within ±3.5° phase error. While an adjustable phase control over 65° is obtained by the phase shifter with varactor diodes, 180° is yielded by that with PIN diodes. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 399–400, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10775 [ABSTRACT FROM AUTHOR]