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A filtering power divider based on air‐filled substrate‐integrated waveguide (AFSIW) technology is proposed in this study. The AFSIW structure is used in the proposed filtering power divider for substantially reducing the transmission losses. This structure occupies a large area because of the use of air as a dielectric instead of typical dielectric materials. A filtering power divider provides power division and frequency selectivity simultaneously in a single device. The proposed filtering power divider comprises three AFSIW cavities. The filtering function is achieved using symmetrical inductive posts. The input and output ports of the proposed circuit are realized by directly connecting coaxial lines to the AFSIW cavities. This transition from the coaxial line to the AFSIW cavity eliminates the additional transitions, such as AFSIW‐SIW and SIW‐conductor‐backed coplanar waveguide, applied in existing AFSIW circuits. The proposed power divider with a second‐order bandpass filtering response is fabricated and measured at 5.5 GHz. The measurement results show that this circuit has a minimum insertion loss of 1 dB, 3‐dB fractional bandwidth of 11.2%, and return loss exceeding 11 dB. [ABSTRACT FROM AUTHOR]

A new planar 3‐band composite right/left‐handed (CRLH) unit cell is presented using an interdigital capacitor, two grounded stubs and etching a defected ground structure on the ground plane. A 3‐band filter is designed using this CRLH unit cell. In addition, with nonlinear dispersion relation of the 3‐band unit cell, it can be used as a hexa‐band quarter wave impedance transformer. Using this functionality, a planar hexa‐band power splitter is designed with relatively good performance. A fabricated prototype of the power divider is measured and the experimental results indicate that the power divider achieved better than 10 dB of return loss and the insertion loss is better than 6 dB over six‐frequency bands. [ABSTRACT FROM AUTHOR]

In this article, a compact single‐layer filtering power divider based on third‐mode circular substrate integrated waveguide (SIW) cavities is proposed. The third‐mode SIW technique is introduced to divide an SIW cavity into three cavities and get 66% size reduction. The proposed power divider is composed of three third‐mode circular SIW cavities within a circuit with the size of a circular SIW cavity. The power is coupled from the input cavity to two output cavities through the electric coupling, separately. To achieve a more size reduction, the designed cavities are corrugated along the cutting planes. By increasing the length of the corrugated edges, the center frequency can be easily shifted to lower frequencies. In order to prove the proposed design procedure, the presented power divider with a second‐order bandpass filtering response is designed and fabricated. Reasonable agreements between the measured and simulated results are found. The measured results show that the power divider achieves an insertion loss of 1.2 dB at 5.61 GHz, return loss of higher than 14 dB, and 3‐dB fractional bandwidth of 7.8%. The results show that this power divider has the advantages of the compact size, high selectivity, and single‐layer structure. [ABSTRACT FROM AUTHOR]

In this paper, a significantly efficient time-domain algorithm is presented to analyze a transmission line, loaded by a nonlinear component and driven by an arbitrary modulated signal. The proposed method provides the envelope of the solution and removes the redundancy of the calculations. The efficiency of this method is achieved in two major steps. First, an unconditionally stable algorithm for the nonlinear circuit is introduced; The derived equations are generated based on the finite-difference time-domain technique and the results are confirmed by those of the Leapfrog method. As the circuit is excited by a modulated signal, decreasing the computational time by using the unconditionally stable algorithm alone, is not practical. Therefore, in the second step, a new time-domain approach is presented and utilized simultaneously, based on separating the high and low frequency behavior of the modulated signal, which enables the advantage of unconditionally stable algorithm effectively. The accuracy of the presented method is confirmed by the Leapfrog algorithm. The comparisons from the given examples indicate that almost 99.97% of the CPU time is decreased by using the proposed method. [ABSTRACT FROM AUTHOR]

A travelling wave structure with two novel functionalities is presented in this brief. The structure benefits from the nonlinear dispersion relation of dual-composite right/left-handed (D-CRLH) transmission line (TL). It consists of two distributed amplifiers (DAs) that have one common gate line and two drain lines. The conventional microstrip TL is used for gate line while the D-CRLH unit cells (UCs) are used to make the drain TLs. When the operating frequencies of D-CRLH TLs of both drain lines are the same, the structure acts as a directional dual-band active power divider (PD). The RF input signal depending on the input signal frequency, is divided into two forward or reverse output ports after amplification. If the D-CRLH TLs have different operating frequencies with no common band, the structure can act as an active quad-plexer or directional quad band amplifier. In this situation, four amplified signals with different frequency bands can be extracted from four different physical output ports. Analysis and design procedure of the structure is provided and a fabricated prototype is measured which shows a good agreement between the simulated results and the measurement results. [ABSTRACT FROM AUTHOR]

In this paper, a high-gain dual-band distributed amplifier (DBDA) based on the metamaterial transmission line (TL) is proposed. To have two separate frequency bands in the distributed amplifiers, the composite right/left-handed (CRLH) TLs are used instead of conventional TLs. Although both forward and reverse gains of the distributed amplifiers are available in this case, they suffer from their low gains. In this paper, to increase the DBDA power gain, a new circuit architecture for the CRLH TL is introduced. By using the proposed CRLH TL, a lower wave attenuation coefficient at the forward band of the DBDA is achieved than the conventional structures, which causes a higher forward power gain. Simulation results also show that the power gain of the proposed DBDA is about 28.5 dB at the desired frequency bands, and good agreement between the measurement and simulation results confirms the accuracy of the design method. [ABSTRACT FROM AUTHOR]

In this study, the extended composite right/left handed (ECRLH) transmission line equations are solved by an unconditionally stable finite‐difference time‐domain algorithm. The results of the proposed algorithm are verified by the conventional one. Amplification matrix of the unconditionally stable algorithm is extracted. The results show that the spectral radius of the amplification matrix of the proposed algorithm is less than one and the proposed algorithm is unconditionally stable. To overcome the numerical dispersion, the complex phasor method is applied to the ECRLH equations. The new equations are solved by the proposed algorithm and results confirm the accuracy of the new equations. By using the complex phasor method and proposed algorithm, the CPU time is reduced about 98%, which shows the efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

The new concept of dual extended composite right/left-handed transmission line (D-ECRLH TL), with 2 right handed and 2 left handed frequency bands is presented. The D-ECRLH TL and extended composite right/left handed transmission line are structurally dual. Therefore, the proposed TL shows the dual properties of the ECRLH TL. The D-ECRLH indeed behaves as a dual-band bandstop filter, in opposition to the ECRLH which is a dual-band bandpass one. In contrast, the D-ECRLH creates an unlimited LH bandwidth. In this article, the transmission parameters and the fundamental properties of the D-ECRLH TL (dispersion and impedance diagrams) are investigated. The results show that the proposed structure is suitable to design the quad-band microwave circuits and systems. A prototype of the proposed D-ECRLH unit cell is realized by the microstrip technology. The good agreement between the measurement and simulation results confirms the realizability of the proposed structure. [ABSTRACT FROM AUTHOR]

In this paper, a four-way dual-band Gysel power divider (GPD)/combiner based on a back-to-back microstrip structure method is proposed and investigated. A two-layer substrate is adopted to implement this PD. In order to divide the input signal into four equivalent signals, the input and four output ports of the proposed PD are placed on the top and the four external isolation resistors are placed on the bottom layer of the substrate. Furthermore, the dual-band response is achieved by adding a short-circuit stub and an open-circuit stub to the structure. Then, the theoretical closed-form design formulas are derived based on the considered conditions and circuit transmission line theory. Finally, for verification purpose, a prototype PD is designed, fabricated, and measured which works at dual frequencies of 1 and 2 GHz simultaneously. The good agreement between simulation and measurement results, which show good impedance matching, isolation, as well as power transmission, verifies the correctness of the design theory. [ABSTRACT FROM AUTHOR]

In this paper, three novel compact metamaterial unit-cells are proposed. The proposed unit-cells are based on the concept of the stepped-impedance resonator (SIR) technique which are used to miniaturize the physical size of the conventional complementary split ring resonators (CSRRs). The proposed metamaterial unit-cells consists of two modified rings so that in these unit-cells, the slot lines in the conventional CSRRs are replaced by the stepped-impedance slot lines. The electrical size of the proposed unit-cells called the SIR-CSRR are larger than the conventional CSRR. To investigate the performance of the proposed SIR-CSRR unit-cells in the size reduction, three substrate integrated waveguide filters loaded by SIR-CSRR unit-cells with different configurations are designed. By loading the SIR-CSRRs on the surface of the waveguide, an additional forward-wave passband propagating below the initial cut-off frequency of the waveguide is produced. Consequently, by using the proposed SIR-CSRR unit-cells instead of the conventional CSRRs, miniaturization with arbitrary ratio are achieved. In order to validate the proposed miniaturization technique, the designed filters are fabricated and measurement results are provided. Good agreement between simulation and measurement results are achieved. [ABSTRACT FROM AUTHOR]

A miniaturized substrate-integrated waveguide (SIW) power divider with embedded filter response and arbitrary power dividing ratio loaded by open complementary split-ring resonators (OCSRRs) is presented. In the proposed power divider, the miniaturization and filtering response are realized by a pair of OCSRRs, which are etched on the metal cover of the SIW structure. The design procedure indicates that the power division ratio can be adjusted by changing the locations of the output ports. In this study, three miniaturized filtering SIW power dividers with different power division ratios (1:1, 1:4, and 1:8) are implemented to evaluate the performance of the proposed structure on the size reduction. These power dividers (1:1, 1:4, and 1:8) have the overall sizes of 0.31λg × 0.14λg, 0.25λg × 0.17λg, and 0.25λg × 0.18λg, respectively. The measured results also agree well with the simulated results. [ABSTRACT FROM AUTHOR]

A power divider/combiner using half-mode substrate integrated waveguide (HMSIW) and microstrip transmission lines with high isolation for high-power applications is presented. The design consists of a planar cavity, two 90° microstrip transmission lines, two matched loads, and one 180° microstrip transmission line. The cavity is fabricated using HMSIW structure and excited the TE101mode at the centre frequency of 4.875 GHz. The external microstrip transmission lines and matched loads are added to improve the isolation between output ports. Moreover, the matched loads prevent the appeared heat loss in the substrate. The circuit behaviour is analysed based on the even and odd mode techniques, and the structure is simulated using a 3D EM simulator. The design is fabricated on a single-layer Rogers RO4003C, and a good agreement between the results of the simulation and measurement is observed. The measured results show that the proposed structure has the insertion loss ofdB, and the isolation and output return loss better than 21.6 and 13.7 dB, respectively, when the return loss of the input port is better than 15 dB (4.8–4.95 GHz). This design has many advantages, such as low cost, low insertion loss, good return loss, good channels isolation, low profile, and compatibility with planar circuits. [ABSTRACT FROM AUTHOR]

In this paper, two miniaturized planar diplexers based on the substrate integrated waveguide (SIW) structure loaded by open complementary split-ring resonators (OCSRRs) are proposed. The working principle is based on the theory of evanescent mode propagation. The proposed SIW diplexers operate below the cutoff frequency of the waveguide. Both the complementary split-ring resonators (CSRRs) and the OCSRRs behave as electric dipoles however, the resonance frequency of the OCSRRs is approximately half of the resonance frequency of the CSRRs. Therefore, the electrical size o f the OCSRRs is larger than the CSRRs. Accordingly, the OCSRRs are more appropriate for the SIW miniaturization. At first, the filtering response of the SIW structure loaded by OCSRR unit cells is investigated. Then, two miniaturized SIW diplexers which consist of two cascaded OCSRR unit cells with different orientations are designed. For the first diplexer (Type I), the fractional bandwidths of operation for the up and down channels are 9.52 % and 2.59 % at 4.2 GHz and 5.8 GHz, respectively. For the second diplexer (Type II), the fractional bandwidths of operation for the up and down channels are 5.95 % and 2.51 % at 4.7 GHz and 5.6 GHz, respectively. Finally, in order to validate the ability of the proposed OCSRR unit cells in the size reduction, two designed diplexers are fabricated and experimental verifications are provided. A good agreement between the results of measurement and simulation is achieved. The proposed diplexers show significant advantages in terms of size reduction, low loss, high isolation, and integration with other planar circuits. [ABSTRACT FROM AUTHOR]

Design and realisation of a compact power divider based on half mode substrate integrated waveguide (HMSIW) with an arbitrary power dividing ratio is presented. This design consists of a substrate integrated waveguide (SIW) transition, two bisected HMSIW transitions by a gap, an SIW-to-microstrip transition, and two microstrip feed lines. In addition, a resistor is attached between two HMSIW transitions. To adjust the power division ratio, four parameters are introduced. Furthermore, four graphs are plotted using a three-dimensional electronmagnetic (3D EM) simulator to graphically determine the introduced parameters. In this study, three circuits with power division ratios of 1:1, 1:4, and 1:8 are simulated using the 3D EM simulator and fabricated on a Rogers RO4003C substrate. The results show a good agreement between the simulated and measured results. The measured results display these circuits (1:1, 1:4, and 1:8) have the bandwidths of 70, 36, and 40%, respectively. Moreover, the proposed structures (1:1, 1:4, and 1:8) are compact and their overall sizes are $1.13 \times 1.04\lambda _g^2 $, $0.96 \times 0.91\lambda _g^2 $, and $0.81 \times 0.78\lambda _g^2 $, respectively. These structures have the advantages of the compactness in size, wide bandwidth, high power division ratio (from 1:1 to 1:16), and compatibility with planar circuits. [ABSTRACT FROM PUBLISHER]

A four-way filtering power divider (PD) based on a substrate-integrated waveguide (SIW) is presented. This structure is composed of two layers of the dielectric substrate. The eighth-mode SIW (EMSIW) technique is used to make four cavities in the upper substrate. In addition, an SIW cavity is provided in the lower substrate. To achieve an efficient transition between the two layers, four rectangular slots are etched on the middle metal planes. A circular slot is etched on the top metal layer of the EMSIW cavities to suppress the higher operating modes. To prove the validity, a four-way PD with a second-order bandpass filtering response is designed and fabricated. The measured results show that the PD achieves an insertion loss of 1.3 dB at 3.5 GHz, a return loss of higher than 17 dB, a 3-dB fractional bandwidth of 7.75%, and an out-of-band rejection of greater than 26 dB from 3.92 to 16.5 GHz. The results show that this PD has the advantages of compact size, high selectivity, and ultrawide out-of-band rejection. [ABSTRACT FROM AUTHOR]

A distributed matrix power amplifier with open-circuit (O.C) composite right-/left-handed (CRLH) transmission line (TL) is proposed. The matrix structure along with the zero phase-shift CRLH TL and the O.C termination of TLs have led to the design of reduced size, high-gain matrix amplifier with improved power performances. A new small size planar CRLH unit cell is presented. The maximum gain of 21.5 dB at the center frequency is obtained. The measured 1-dB gain compression (P1-dB) is 26 dBm, and the maximum power added efficiency is 29%. Better gain and P1-dB are achieved compared to the previously published narrowband distributed amplifiers. The amplifier has good linearity according to the measured input intercept point (18 dBm) and the output intercept point (39 dBm). [ABSTRACT FROM AUTHOR]

ABSTRACT This article introduces a modified Gysel power divider, providing high power division ratios, alongside the advantage of high power handling. To overcome fabrication limitations of high characteristic impedance line, caused by the anticipated high power division ratio, a coupled line structure with two shorts is used. This proposed structure makes closed-form equations available for design and leads to a simple microstrip fabrication. A 10:1 unequal Gysel power divider is presented and fabricated as a design example and a satisfactory agreement between measurements and simulation results is verified. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2689-2692, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT A compact substrate integrated waveguide (SIW) with open complementary split-ring resonators (OCSRRs) loaded on the waveguide surface is proposed. The OCSRRs can be interpreted in terms of electric dipoles and they are good candidates to behave as electric scatterers. By loading OCSRRs on the waveguide surface, a forward-wave pass-band propagating below the waveguide cutoff frequency is generated. The resonance frequency of the OCSRRs is approximately half of the resonance frequency of the complementary split ring resonator (CSRR). Therefore, the electrical size of this particle is larger than the CSRRs and the OCSRRs are more appropriate for the SIW miniaturization. A bandpass response with a sharp rejection frequency band is obtained by properly manipulating the structure of the elements. By changing the orientation of the OCSRRs, two types of unit cell are proposed. Moreover, by resizing the OCSRRs, resonance frequency can be easily moved and the bandwidth can be tuned by the coupling between two OCSRRs. Compared with some other reported bandpass filters (BPFs) with SIW technique, the presented BPF has great improvements on size reduction and selectivity. To verify the methodology, two filters with center frequency of 5.5 GHz are designed and measured. The measured results are in good agreement with the simulated ones. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:674-682, 2016. [ABSTRACT FROM AUTHOR]

In this study, an unconditionally stable finite difference time domain algorithm for time domain analysis of the active multiconductor transmission lines is presented. The results of the proposed algorithm are compared with the results of the conventional algorithm. While the results of the proposed algorithm have a very good accuracy, the CPU time of the proposed algorithm is less than (about 90%) that of the conventional one. The amplification matrixes of the proposed and conventional algorithms are extracted and numerical stability of them are investigated. The spectral radius of the presented algorithm is smaller than one for any temporal step sizes and the proposed algorithm is unconditionally stable. [ABSTRACT FROM AUTHOR]

An unconditionally stable finite-difference time-domain method to analyse the composite right/left handed (CRLH) transmission lines (TLs) is proposed. The conventional algorithm presented to analyse the CRLH TLs is not capable of analysing special case of the CRLH TLs such as pure left-handed TLs due to numerical stability problem. The proposed unconditionally stable algorithm removes the numerical instability and can analyse all the CRLH and pure left-handed TLs. Amplification matrix of the proposed algorithm is calculated and numerical stability of the presented algorithm is studied. The proposed algorithm is applied to some examples and results are verified by the results of the conventional algorithm and results of Agilent ADS software. The results indicate that the CPU time of the proposed algorithm is reduced about 99% than that of the conventional algorithm by using the complex phasor method and unconditionally stable algorithm. [ABSTRACT FROM AUTHOR]

In [1] a dual-band Gysel power divider(PD)/power combiner(PC) has been proposed. Some equations have been extracted to determine the characteristic impedances of the transmission lines. However, there may be some possible mistakes in some of them, because the impedance values which have been realized do not satisfy the equations. [ABSTRACT FROM PUBLISHER]

In this article, a set of differential equations to model the behavior of the extended composite right/left handed transmission line in time domain is proposed. These equations are solved by an explicit finite difference time domain algorithm. To investigate the numerical stability of the proposed algorithm, the amplification matrix is extracted. The results of the proposed algorithm are confirmed by the results of the Agilent ADS commercial software. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:68-76, 2014. [ABSTRACT FROM AUTHOR]

In this article, a compact, wideband, and sharp rejection response bandpass filter based on metamaterial unit-cell concept is proposed. A series LC resonator using an interdigital capacitor and two meanders is designed, and an open complementary split ring resonator is used to realize the parallel LC resonator. Due to parasitic elements, achieving a pure series LC resonator has some difficulty. However, these parasitic elements can add two resonances more than conventional filters based on the metamaterial unit-cell. A design procedure based on a simple equivalent circuit is introduced. A compact bandpass filter at 1.475 GHz, with 94% fractional bandwidth, and an attenuation slope with 85.98 and 35.628 dB/GHz in the lower and upper transition bands, respectively, is designed and fabricated. The measured results are in good agreement with the full-wave electromagnetic simulations inferred by means of Agilent Momentum. The filter has very small size, that is, 0.341λ g × 0.1033λ g, where λ g is the guided wavelength at the filter central frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2832-2835, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27185 [ABSTRACT FROM AUTHOR]

In this paper, an unconditionally stable finite-difference time-domain algorithm is presented for analysis of lossy nonuniform multiconductor transmission line (MTL). The results of the proposed algorithm are confirmed by those of the Leap-Frog algorithm. The unconditionally stable algorithm alone cannot decrease the time consumption, especially when the MTL is excited by modulated signals. The complex phasor transformation approach is used to separate the modulating signal from the carrier signal when an MTL is excited by a modulated signal. A new set of equations is generated using this approach. The new equations are based on the modulating signal, and the carrier signal is eliminated in these equations. The derived equations are solved by Leap-Frog algorithm, and the results confirm the accuracy of these equations. Finally, the proposed equations are solved by the unconditionally stable algorithm at several temporal step sizes. The results indicate that this method has much lower CPU time compared with the conventional method and also has a very good accuracy. [ABSTRACT FROM AUTHOR]

In this study, a reconfigurable triple‐band triple‐mode substrate integrated waveguide filter is designed and fabricated in the C‐band spectrum. A novel and simplified design procedure based on analytical equations is proposed. The filter design also benefits from a reconfigurable structure, using metallic via holes as perturbation, allowing wide‐band selectivity of the C‐band spectrum (from 4.4 to 6.9 GHz). Moreover, the filter benefits from a magnetic coupling solution between the resonators, which only couples the first three modes and rejects the next resonating modes. Therefore, a large bandgap in the spectrum is achieved. The proposed structure is fabricated and measured, and a high similarity between the simulation and fabrication is observed. The measured results show that the first band can be tuned in the frequency range of 4.4 to 7, the second band can be tuned in the range 5.8 to 7.7 GHz, and the third band from 5.8 to 7.7 GHz. The insertion loss 1.5 to 2.5 dB, 2 to 3 dB, and 2.5 to 3.5 dB for the first, second, and third bands, respectively. [ABSTRACT FROM AUTHOR]

In this paper, two ultracompact power dividers based on the substrate integrated waveguide (SIW) and half‐mode SIW (HMSIW) technologies loaded by complementary split‐ring resonators (CSRRs) are presented. The presented structures are designed based on the theory of evanescent mode propagation. To obtain a size reduction, the CSRR unit cells are etched on the metallic surface of the SIW and HMSIW structures. First, a two‐way HMSIW power divider is reported. In this circuit, the concept of HMSIW is utilized aiming at a further size reduction in addition to the size reduction by the CSRR unit cells. Then, a four‐way SIW power divider is designed so that the direct coaxial feed is used for the input port and microstrip transmission lines are used for the output ports. Both two‐way and four‐way SIW/HMSIW power dividers at 5.8 GHz covering WLAN are designed, fabricated, and measured. They respectively have 0.18 × 0.21 λg2 and 0.38 × 0.21 λg2 total size. A fair agreement between simulated and measured results is achieved. The measured insertion losses are 0.5 ± 0.5 and 0.6 ± 0.5 dB for the two‐way and four‐way SIW/HMSIW power dividers, respectively, in the operating band of interest. [ABSTRACT FROM AUTHOR]

A novel super compact filter based on half‐mode substrate‐integrated waveguide (HMSIW) technology loaded by the modified complementary split‐ring resonator (MCSRR) is proposed. The working principle of the proposed filter is based on the evanescent‐mode propagation technique. According to this technique, by loading the complementary split‐ring resonator (CSRR) on the metal surface of the substrate‐integrated waveguide (SIW) structure, an additional passband below the SIW cutoff frequency can be obtained. In order to miniaturize the physical size of the conventional CSRR, a new method is introduced. In the proposed MCSRR unit‐cell, the meander slots are carved inside all of the interior space of the ring. Accordingly, the length of the slot is increased which leads to an increase in the inductor and capacitor of the proposed structure without occupying the extra space. Therefore, the electrical size of the proposed MCSRR unit‐cell is reduced. Consequently, the resonance frequency of the proposed MCSRR unit‐cell is decreased compared to the conventional CSRR with the same sizes. Namely, the lower resonance frequencies can be achieved by using this technique without increasing the size of the unit‐cell. In order to confirm the miniaturization technique, two HMSIW filters loaded by the proposed MCSRR unit‐cell are designed, fabricated, and experimental verifications are provided. The results show that a miniaturization about 67% is achieved. [ABSTRACT FROM AUTHOR]

In this article, a new miniaturized metamaterial unit‐cell using stepped‐impedance resonator technique is proposed. The proposed unit‐cell is used to miniaturize the physical size of the conventional complementary split‐ring resonators (CSRRs). In the proposed unit‐cell which is called complementary G‐shaped resonator (CGR), the slot line in the conventional circular CSRR is replaced with the stepped‐impedance slot line. As well as, by carving two trapezoidal shapes inside the inner ring, the resonance frequency of the proposed CGR unit‐cell has been more decreased. Compared to the conventional circular CSRR structure, the electrical size of the proposed CGR is decreased and miniaturization is occurred. To investigate the performance of the proposed CGR unit‐cell in the size reduction, two substrate integrated waveguide filters and a diplexer are designed. To validate the proposed miniaturization technique, the designed filters and diplexer loaded by the CGR unit‐cell are fabricated and measured. The measured results are in a good agreement with the simulated ones. The results shows that, a miniaturization factor about 0.69 is achieved. [ABSTRACT FROM AUTHOR]

A high‐gain dual‐band distributed amplifier (DBDA) based on the dual‐composite right/left handed transmission line (D‐CRLH TL) is presented. Both forward and reverse gains of the DAs are simultaneously available, when their conventional TLs are replaced by the metamaterial TLs. To improve the performance of the DBDA, a new D‐CRLH with a narrower stop band than the conventional D‐CRLH is proposed. This leads to enhanced bandwidth for the proposed DBDA. In addition, the introduced TL increases the reverse power gain of DBDA, by decreasing the wave attenuation coefficients at this band. The results show that the DBDA achieves 31.5 ± 1.4 dB forward power gain with a 3 dB bandwidth of 2 GHz (from 0.8 to 2.8 GHz) and 31.5 ± 1.5 dB reverse power gain with a 3 dB bandwidth of 2.5 GHz (from 5 to 7.5 GHz). The good agreement between measurement and simulation results confirms the accuracy of the design method. [ABSTRACT FROM AUTHOR]