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This paper presents a generalized geometrical equivalent circuit model for a strip-loaded coplanar waveguide (CPW) that carries the even and odd modes simultaneously. The proposed model enables the analysis, sets the design requirements, and defines the constraints of the realization of an air-bridge free all CPW Wilkinson power divider (WPD). To overcome these constraints, this paper proposes two implementations. The first one engineers the dispersion relation of the odd mode to provide a slow-wave factor that compensates the difference in the electrical lengths with the even mode, while the second implementation deploys the floating strips as electrical air-bridges. The proposed power dividers are designed to operate at 2.4 GHz. Measurements, which are in good agreement with the EM simulations, confirm the theoretical predictions. [ABSTRACT FROM AUTHOR]

This paper presents geometrical-based wideband circuit models for different configurations of loaded slotline and loaded coplanar waveguide (CPW). It investigates, first, the strip-loaded slotline and then extends the developed model to strip and split-ring resonator (SRR)-loaded CPW. The proposed models successfully describe the behavior of several structures of interest in the literature and provide new insights on the design procedure. They operate over the entire frequency range if higher order modes are not generated without the need for fitting parameters. This paper also presents three applications, of which the design relies on the proposed modeling methodology. They are a third order maximally flat low-pass filter with 1.4-GHz cutoff frequency, a 3-GHz slow wave structure with a slow wave factor larger than 2 in the linear range of the dispersion relation, and a balanced composite right-/left-handed SRR-loaded CPW with 100% (2.31–7.1 GHz) fractional bandwidth. Experimental results, which are in a very good agreement with the electromagnetic simulations, confirm the proposed theory. [ABSTRACT FROM AUTHOR]

This paper proposes the use of the coplanar waveguide (CPW) odd mode, also known as the parasitic slotline mode, as a design parameter. It presents a novel equivalent circuit model for the CPW cross-junction, where each CPW has two modes: the even mode, which is the conventional CPW mode also known as the coplanar mode, and the odd mode. The model is simple, intuitive, and physical-based. It can be used in different combinations including the case of slotline cross-junction. The model paves the way to design novel air-bridge free CPW applications. Among them, two are presented in this paper: CPW-to-slotline transition (balun) and Wilkinson power divider. For both applications, closed form expressions for the operating point are derived. Results are verified by EM simulations. An air-bridge free CPW power divider that combines both applications is fabricated and characterized. Simulations and measurements are in a very good agreement. [ABSTRACT FROM PUBLISHER]

Quad-band slow-wave (SW) printed inverted-F antennas (IFA) for 0.9 GHz, 1.57 GHz, 1.8 GHz, and 2.45 GHz are proposed. Multi-band behavior is achieved by combining L-loaded printed-IFA and two printed radiators. Each of the four radiators has a small effect on the performance of the other radiators. Compact printed-IFA antennas are realized using SW structures such as saw-tooth, meander lines, first fractal iteration and high impedance wire (HIW). A size reduction of 40% is achieved. The proposed antennas maintain the same far-field radiation patterns of the conventional printed-IFA. They also possess the properties of good performance, compact size, low profile, and low cost. Hence, they are suitable for implementation in wireless applications. [ABSTRACT FROM PUBLISHER]

Component-loaded antennas are treated as antennas with internal ports. The proposed model explains, through simple numerical simulations and an optimization algorithm, the behavior of these antennas over a wide band. Two examples are studied; dipole-based antennas loaded with one internal port and two internal ports. Based on the proposed analysis, a UHF (0.47 GHz–0.86 GHz) antenna is designed and measured. It has 2 cm\, \times\,5 cm area, less than -6 dB reflection coefficient, omni-directional radiation pattern, and more than 90% efficiency. Measurements confirm the theoretical predictions. [ABSTRACT FROM PUBLISHER]

A new compact size microstrip arbitrary coupling directional coupler (DC) based on the coupled line composite right/left handed (CL-CRLH) unit cell is proposed. The coupler is patterned on a single metal layer, does not use vias, and occupies 45 × 11 mm2 area. Its bandwidth is 400 MHz centered around 2.4 GHz and it provides −3 dB coupling coefficient. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:115-119, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27270 [ABSTRACT FROM AUTHOR]

The theory and implementation of a new family of monopole antennas loaded with composite right/left handed (CRLH) unit cells are presented. The proposed antennas have a number of narrow bands that is twice the number of unit cells and one wide band that is centered around the monopole original frequency. The new operating frequencies are below the original one and they are controlled by the unit cell dispersion relation. The proposed antennas occupy the same Chu sphere as the original monopole, all the operating frequencies have omni-directional radiation patterns, and matching is better than -10 dB. Three antennas are realized; the first is loaded with one distributed CRLH unit cell, the second is loaded with lumped components CRLH unit cell, and the third is loaded with two CRLH unit cells. All proposed antennas are fabricated and measured. Measurements and EM simulations confirm the proposed theory. [ABSTRACT FROM PUBLISHER]

In this article, a new composite right/left-handed (CRLH) antenna is proposed. The antenna is implemented by cascading dual-function coplanar waveguide coupled line CRLH unit cells. The proposed antenna has continuous backward to forward radiation. The scanning angle, radiated power and directivity increase as the number of cells increases. For nine cells, the scanning angle is 77°, the radiated power is 75%, the peak directivity is 4.2, and the total length is smaller than λ0. The circuit and EM simulations have been confirmed by measurements. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:103-107, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26483 [ABSTRACT FROM AUTHOR]

Novel three-dimensional antennas that provide either multibands or ultra-broadband are presented. The proposed structures are based on monopole antennas loaded with meander lines. For operation of multibands, the monopole is loaded with different-length meander lines connected in series. The proposed antenna has 55 × 66 × 130 mm3 volume and operates in the following bands: 200 MHz, 800 MHz, 1.1 GHz, 1.4 GHz, 2.45 GHz, 3 GHz, and 3.7 GHz. Ultra-broadband is achieved by connecting four monopoles in parallel. Each monopole is loaded with two meander lines. The resulting bandwidth extends from 400 MHz to 3.5 GHz, which is suitable for digital video broadcasting-T applications, and the size is 53 × 68 × 87 mm3. Both antennas have omnidirectional radiation patterns. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2843-2846, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26417 [ABSTRACT FROM AUTHOR]

This article presents a balanced composite right/left-handed (CRLH) transmission line using high impedance wire.No vias are required in the proposed implementation. However, processing of double surfaces is needed. The proposed structure provides multiple CRLH bands. The concept was validated in microstrip configuration, and equivalent circuit model was proposed and theoretical expectations were confirmed by EM simulations and measurements. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1390–1393, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25215 [ABSTRACT FROM AUTHOR]

This paper presents two applications of the coupled- line composite right/left-handed (CL-CRLH) unit cell, compact-size rat-race hybrid, and arbitrary coupling directional coupler. Benefiting from the slow-wave effect present in both the right- and left-handed regions of the CL-CRLH unit cell, two compact-size rat-race hybrids were realized. 60% area reduction was achieved while preserving the conventional rat-race performance. The arbitrary coupling directional coupler, which operates in the stopband around the balance frequency, showed excellent in-band and out-of-band performance. To reduce its size, a slow-wave CL-CRLH unit cell was proposed. The proposed unit cell achieves a 38% size reduction. The rat-race hybrids were fabricated on microstrip technology, whereas the directional couplers were fabricated on stripline technology. Simplified circuit models for the unit cells were developed. Theoretical expectations were confirmed by electromagnetic simulations and measurements. [ABSTRACT FROM AUTHOR]

Two new structures, defected slotline and patch-loaded coplanar waveguide (CPW), are introduced and quasi-static geometrical models for them and for the defected ground structures in microstrip and in CPW configurations are developed, combining those structures with the patch-loaded slotline and the stepped impedance resonators (SIRs) in a microstrip; and thus, a unified approach for the realisation of series and parallel stubs in different planar transmission line configurations is presented. Complementarity between the different structures has been investigated. It has been found that an identical dumbbell-shaped defect and a SIR in a microstrip are complementary to each other. Consequently, a new technique is developed to compensate for the effect of a defect in the ground of a microstrip. All theoretical predictions have been confirmed with both EM simulations and measurements. [ABSTRACT FROM AUTHOR]

In this article we present an RF optoelectronic oscillator based on directly modulated laser diode and an all optical RF filter. The system is modeled and simulated using standard simulators. Using commercial modules and standard single mode fiber, the implemented system shows an RF oscillation with 9.8 dBm at 1.1 GHz. We also show that the use of an all optical RF filter allows a sidemode suppression ratio more than 50 dB without affecting the signal purity. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 470–475, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24069 [ABSTRACT FROM AUTHOR]

Defected-ground coupled lines (DCL) is introduced. It consists of edge coupled microstrip lines with a defected ground. The equivalent circuit model, which is based on separating the two modes of the coupled lines into the common and differential modes, is also developed. The model is validated by comparing the results of ten conventional coupled-line circuits using DCL with EM simulations and excellent agreement was achieved (error is less than or equal to 1.5%). In DCL, the propagation characteristics of the common and differential modes are controlled separately. This permits the design of novel wideband baluns that have a reduced area and a superior performance compared with the multisection quarter wavelength coupled-line baluns. Design guidelines of the proposed baluns are detailed, and single-section and three-section DCL-baluns are implemented. The single-section DCL total length is 0.16λ, it provides 10% increase in fractional bandwidth, and it occupies 60% of the area when compared with the five-section quarter wavelength balun bandwidth and area, respectively. The single-section and three-section baluns have a fractional bandwidth of 40 and 70%, a maximum amplitude balance of 0.5 dB (for both) and a maximum phase balance of 10° and 3°, respectively. Measurements, circuit and EM simulations of one conventional coupled-line circuit with DCL and the two baluns are in excellent agreement. [ABSTRACT FROM AUTHOR]

Defected ground structure and split ring resonator are combined to form a compact dual bandstop filter or a dual pole bandstop filter. An equivalent circuit model is developed for the proposed structure and it agrees very well with EM simulation. A dual bandstop resonator was fabricated. Measurements and theoretical predictions are in a very good agreement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1249–1253, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22464 [ABSTRACT FROM AUTHOR]

A modification of the conventional dumbbell-shaped coplanar waveguide defected ground structure (DGS) is proposed. This modification permits the continuous tuning of the rejected frequencies by using reconfiguration technique and it allows the control of the DGS equivalent-circuit model. The modified DGS possesses two-dimensional symmetry, hence, it has been studied under different symmetry conditions and the corresponding equivalent-circuit model in each case has been developed. Based upon this study, a tunable bandstop DGS resonator is proposed. 19% tuning range centered at 3.7 and 7.4 GHz, respectively, is achieved. The equivalent-circuit model of the resonator is also developed. All proposed structures have been fabricated. Measurements as well as three-dimensional simulations are found to be in a very good agreement with theoretical predictions. [ABSTRACT FROM AUTHOR]

A MEMS reconfigurable defected-ground-structure (DGS) resonator using two-dimensional (2-D) periodic DGS for coplanar waveguide (CPW) transmission line and RF MEMS series-resistive switches is proposed. The introduced MEMS reconfigurable DGS resonator has approximately a fixed bandwidth of 8.1 GHz over a wideband frequency range (K-band). The proposed structure can be designed easily for other frequency bands by changing the number of unit-cells of the 2-D PDGS. A cascaded two parallel-resonance circuit model for the MEMS reconfigurable DGS resonator has been introduced as well. The equivalent circuit parameters extraction methods have also been derived. Simulations based on the proposed circuit model are in a very good agreement with the electromagnetic (EM) simulations, which suggests that the MEMS reconfigurable DGS resonator is an inductive controlled reconfigured structure. The structure is designed in CPW environment on a high-resistivity silicon substrate. It is therefore suitable for monolithic integration with standard IC process. [ABSTRACT FROM AUTHOR]

A new family of compact rat-race hybrid couplers is proposed. The novelty of the new structures stems from the idea of utilizing the vacant space inside the conventional rat-race coupler in increasing the rat-race ring path. The couplers have been designed to operate at 1.8 GHz. The size of the new structures is 70% less than conventional rat-race hybrid coupler at the same center frequency. The measurements are in good agreement with the designed values. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 606–609, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21421 [ABSTRACT FROM AUTHOR]

The behaviour of the electromagnetic field in an L-shaped defected-ground structure (DGS) for a coplanar waveguide (CPW) has been investigated and the parameters affecting the inductance, the capacitance and the resistance are separately determined. Numerical experimentation of the effect of different design parameters has been carried out, which leads to a very wide variation of the band-stop frequency (2.8-10.5 GHz). Based on parameter sweeping, two wideband band-stop filters have been designed using four cascaded cells of double-sided, two-section, L-shaped DGS. The central frequencies achieved are 6.0 and 3.7 GHz and the band-stop widths are 2.8 and 2.0 GHz with rejection larger than 30 and 25 dB, respectively. All numerical investigations have been confirmed experimentally and excellent agreement has been achieved. [ABSTRACT FROM AUTHOR]

An RF on-wafer probe is simulated using commercial 3D simulation software. The two-port simulated S-parameters are found to be in a good agreement with the experimental data. The model is extended to study the microstrip-mode effects in a typical RF on-wafer probe. The microstrip mode is studied as the mode between the probe coax outer conductor and the wafer chuck. The microstrip-mode reflection coefficient looking into the probe tips is determined for the first time. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 324–328, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20812 [ABSTRACT FROM AUTHOR]

Two metal–semiconductor–metal (MSM) photodetectors are integrated monolithically with a coplanar waveguide transmission line to form a 1.55-μm surface-illuminated balanced photodetector. Illuminating the device with CW and taking the difference, the relative intensity noise (RIN) is suppressed by 9–10 dB. In balanced detection, a 7-dB enhancement in the intermodulation term compared to single detector is achieved. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 125–130, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10393 [ABSTRACT FROM AUTHOR]

In this work we present a new optically controlled microwave matching technique. In this technique the gap between two microwave coupled lines is illuminated by an optical spot of suitable wavelength. The structure is then used as a load in a microwave circuit. By controlling the spot intensity and position, we control the matching frequency of the circuit. The microwave behavior of the illuminated load is obtained using the MMICAD (monolithic microwave integrated circuit analysis and design) simulator. Experimental results using a p-type Si substrate in agreement with the theoretical predictions are also obtained. [ABSTRACT FROM AUTHOR]

This article presents a novel lumped-element equivalent circuit model for split-ring resonator (SRR)-based composite right/left-handed (CRLH) coplanar waveguide (CPW). The proposed model has closed-form expressions in terms of the parameters of the constituent transmission lines and is valid over a wide frequency range. This article also presents a novel slotline to coupled microstrip (MS) line $E$ -plane T-junction. Based on the circuit model and the proposed junction, systematic design procedures for ultrawideband balanced SRR-based CRLH CPW unit cells that benefit from the geometry of the unit cell and do not rely on adding extra components or parametric iterations are developed. This article also explains the layout constraints and presents alternatives to realize wideband designs. Two CPW unit cells using SRR and edge-coupled (EC) SRRs are designed, fabricated, and characterized. Simulations, which are in good agreement with measurements, show that the operating bandwidth can reach 97% and 78.21% for the two cells, respectively. [ABSTRACT FROM AUTHOR]

Defected-ground coupled microstrip lines (DCL) bandpass filter is proposed. The length of the proposed filter is quarter the length of conventional coupled-line filter and it has a wide stopband and suppressed spurious resonances up to 4f0, where f0 is the filter central frequency. Five hundred and fifty megahertz single-section and two-section DCL filters were designed and fabricated. Simulations and measurements show that the rejection levels of the spurious resonances at 2f0, 3f0 as well as 4f0 are better than -11 and -14 dB for single-section DCL and double-section DCL, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2038–2039, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22590 [ABSTRACT FROM AUTHOR]

A dual-mode microstrip bandpass filter using the degenerate modes of a modified square ring structure is proposed. The size of the new structure is 50% less than conventional dual-mode bandpass microstrip square resonator filters at the same centre frequency. Measurements are in good agreement with designed values. [ABSTRACT FROM AUTHOR]

Electrically-small antennas can be designed using inductively-loaded dipoles. A simplified design procedure is carried out, using circuit models and EM simulations, to implement efficient dual and wide-band antennas with omni-directional radiation patterns. Measured performance agrees with simulations, and the proposed designs are employed for the UMTS 1.8/1.9/2.1/2.6-GHz and WLAN 2.4/3.6-GHz frequencies. A USB dongle antenna is prototyped to cover these frequency bands with impedance bandwidth reflection coefficient better than -10 dB. [ABSTRACT FROM PUBLISHER]

This letter proposes a new interpretation for the Z-antenna.It describes the Z-antenna as an asymmetrically-fed bent and meandered inductively-loaded dipole antenna. This explanation provides a simple methodology to design a dual-band stripline-fed Z-based antenna that operates at 1.8 and 2.45 GHz. Measurements and EM simulations validate the proposed theory. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:286-290, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27307 [ABSTRACT FROM AUTHOR]

Slow-wave coplanar striplines (S-CPS) have been implemented in the standard AMS 0.35 μm CMOS technology. Compared to conventional coplanar striplines (CPS), at 20 GHz, the proposed S-CPS line has more than 675% increase in quality factor, 54% improvement in the attenuation constant and 72% reduction in the electrical length. The RLCG model has also been extracted and the sources of losses have been identified. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:650-654, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26645 [ABSTRACT FROM AUTHOR]

This Letter presents a novel pseudo-omnidirectional antenna that is appropriate for wide beam applications, e.g. handheld devices, along with a reduced back radiation that suits wearable applications as well. The design consists of a horizontal omnidirectional antenna placed on a proposed artificial magnetic conductor (AMC) surface that enhances the gain in the broadside direction, reduces the back radiation, and enables good radiation in the side directions. A 5 GHz folded dipole on a 2 × 2 AMC array surface is designed and characterised. Simulations and measurements, which are in a very good agreement, show that the radiation has a heart-shaped pattern, with a front to back ratio of >13 dB, a front to side ratio of <2.5 dB, and a half-power beam width of >230°. [ABSTRACT FROM AUTHOR]

A dual-band phased array antenna prototype for the Federal Communication Commission automotive short-range radar and long-range radar operating at 25.5 and 76.5 GHz with a scaling factor of 1:20 is presented in this paper. A complete design methodology for dual-band phased array antenna is also proposed. A dual-band bowtie antenna that satisfies the application requirements is designed and fabricated. An isolation technique is adopted to minimize the coupling between the closely spaced elements in the array. A full scaled prototype is fabricated on FR4 substrate. The simulated and measured results are in good agreement. [ABSTRACT FROM PUBLISHER]

In this article, shielded coplanar striplines (S-CPS) are studied to achieve slow-wave transmission lines in a CMOS process. The slow-wave propagation is achieved by placing floating strips below the CPS transmission line. The propagation parameters of such transmission lines are derived by simulations by means of a “full wave” 3D EM software. Quality factors as high as 35 at 10 GHz together with effective dielectric constants of 78 are reported. If these simulation results are confirmed by measurements, this would open the door to the possible realization of integrated transmission line-based RF circuits such as power dividers, phase-shifters, or filters of medium bandwidth below 10 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 352–358, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24054 [ABSTRACT FROM AUTHOR]

Two optically controlled phase shifters are proposed. The first structure is based on the microstrip ring resonator inserted between two gaps. Phase-shifting is performed by optically controlling the gaps capacitance. The structure has shown excellent characteristics, however the rejection rate is high. To minimise the reflected power, the second phase shifter, which is based on the rat race coupler, is proposed. In this case, the phase-shifting is performed by adding extra lengths to two gaps, judiciously placed along the microwave ports. The gaps act as short-circuits under sufficient illumination conditions. At 10 GHz, the structure provides a continuous variation of Δϕ(S21) between 0 and 90°, with Δ|S21| less than 5dB. On a 500 MHz band around 10 GHz, the phase variation is less than 5%. |S11| keeps <⁕20 dB within the experimental bandwidth 8.9–10.7 GHz. Both structures were fabricated on high-resistivity silicon substrate and the experimental results confirm the three-dimensional electromagnetic simulations. [ABSTRACT FROM AUTHOR]