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This article presents a flexible four-element antenna for X-band applications. The proposed antenna covers the spectrum ranging from 10.6 to 11.9 GHz, including a significant portion of the X-band. The single antenna element comprises a modified E-shaped radiating patch, which is fed by a unique feeding structure consisting of a 50-Ω feeding strip connected with two rectangular stubs on both sides. All antenna elements are printed on a flexible felt 60 mm × 60 mm × 1 mm (2.12 λ × 2.12 λ × 0.035 λ at 10.6 GHz) substrate. The proposed antenna exhibits circular polarization over the desired bans of operation with an axial ratio (< 3 dB) bandwidth of 1.2 GHz, which is significant for X-band applications. The designed antenna is manufactured and practically tested. Both simulated and measured results agree well with each other, ensuring the optimal performance of the antenna. Moreover, the antenna achieves a maximum gain of up to 8 dBi in the desired band of operation. Further MIMO parameters, including envelope correlation coefficient (ECC), diversity gain (DG), channel capacity loss (CCL), and mean effective gain (MEG), are calculated to validate the MIMO performance. Finally, a conformal analysis was carried out to study the robustness of the antenna in various bending scenarios. Results show that the antenna reported in this article is the correct choice for conformal X-band MIMO applications. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surface (RIS) is one of the possible solutions to overcome challenges that bring up the 6G communication networks. Unit cell design for RIS is similar in many aspects to the design of artificial magnetic conductors (AMC) because both have a common nature of changing the phase of the reflected wave. However, RIS is aimed at controlling the angle of reflection to maintain requirements for the radiation pattern similar to phased antenna arrays such as low side lobes and beamwidth. The paper reviews the criteria for optimizing RIS: unit cell dimensions, phase span, frequency bandwidth, and loss. An optimization algorithm is proposed for the proper accounting of RIS optimization criteria. A new X-band unit cell is designed using the proposed optimization algorithm. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a meander-feed antenna system featuring circular polarization (CP) diversity and high isolation. The antenna design comprises a monopole antenna and an isosceles triangular partial ground on a single layer. This innovative structure departs from traditional antennas in three significant ways: it achieves structural asymmetry by modifying the antenna's shape and position, which enhances CP characteristics; and it transitions the feeding structure from a linear to a meander type. Experimental results show that the proposed antenna covers frequency ranges of 6.9–8.5 GHz and 9.2–10.1 GHz, with measured isolation below − 12 dB within the operating bandwidth. As a result, the single monopole antenna attains a CP bandwidth of 20.78% and 9.33%. The single-element CP antenna is then incorporated into a 4-port MIMO antenna, which is fabricated and measured, demonstrating excellent agreement between simulated and measured results. The proposed antenna system achieves an overall gain of 5 to 8 dBi across the operating spectrum, making it an ideal choice for X-band applications. [ABSTRACT FROM AUTHOR]

In this research, a quad‐band sickle‐shaped MIMO antenna of compact size 32 × 32 mm2 (0.28λ0 × 0.28λ0 at lower resonant frequency 2.6 GHz) has been proposed using partial ground and tilted isolation stub at an angle of 45°. It covers 2.40 to 2.80 GHz frequency range with bandwidth (BW) of 15.38% (0.40 GHz) which is applicable for Wi‐Fi application in first band and in second band it covers from 4.48 to 5.75 GHz frequency range with BW of 24.83% (1.27 GHz) for WLAN application. In addition, the third band starts from 9.75 to 10.43 GHz frequency range with BW of 6.74% (0.68 GHz) for the X‐band whereas in fourth band it covers from 13.07 to 15.87 GHz frequency range with BW of 19.38% (2.8 GHz) frequency, which is applicable on Ku‐band application. Moreover, the isolation is < −15 dB in the entire resonating frequency band which is an acceptable limit for reduction of mutual coupling. ECC value is <0.5 in the entire operating band of frequency. The diversity gain of the proposed MIMO antenna is approximately 9.96 dB that shows the antenna exhibits good diversity property. The channel capacity loss value is <0.4 bps/s/Hz in the entire resonating band. In view of all the diversity parameters, the proposed MIMO structure fulfills all the requirements of the MIMO antenna. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive analysis of the design of a high-performance meta-material loaded square patch antenna arrays specifically tailored for X-band applications. To enhance the gain and front to back ratio (FTBR), a novel 1x3 series-fed linear array configuration that integrates solitary series-fed elements with metamaterial-based square patches at X-band frequencies is introduced. Later, parallelfed 1x2 and 1x4 antenna arrays are designed by considering the series-fed antenna array as a single element for further enhancement of gain and FTBR. The single element 1x3 series fed array is fabricated with dimensions of λx3.5λx0.028λ, whereas the respective 1x2 and 1x4 parallel fed antenna arrays has the dimensions of 2.86λx3.8λx0.028λ and 2.86λx4.3λx0.028λ, respectively. The Taconic substrate is chosen as the dielectric material, exhibiting a dielectric constant of 2.2 and a loss tangent of 0.0025. The empirical data presented substantiates the superior performance of the 1x4 parallel fed configuration. This is evident through the remarkable reflection coefficient of -25dB, the wide bandwidth spanning 47MHz, the substantial gain of 17.8dBi, and the FTBR of 30.7. The metrics serve to highlight the array's capacity in guaranteeing a superior level of signal fidelity, encompassing a wide frequency spectrum, amplifying incoming signals, and directing transmissions towards specific orientations. These metrics unequivocally validate its potential for advanced X-band applications. [ABSTRACT FROM AUTHOR]

This study presents an original parallel connected hybrid microstrip-substrate integrated waveguide (PCHMSIW) bandstop filter. A low-pass filter implemented on a microstrip structure and a SIW-based high-pass filter are connected in parallel to each other. In this way, the aim is to obtain a bandstop filter in the novel hybrid design. The parallel connected hybrid microstrip-substrate integrated waveguide (PCHM-SIW) bandstop filter is synthesised, simulated, and produced. The effects of connecting filters in parallel are discussed. It is seen from the results of CST Studio Suite simulation that PCHM-SIW bandstop filter has a bandwidth of 2.85 GHz and a center frequency of 4.26 GHz. The frequency change rate of the center frequency between simulation and measurement is 7.02 % where it is just 3.76 % for the deviation in bandwidth. The results of the simulation and those of the measurement are close to each other. These results converge to ideal analytical results. [ABSTRACT FROM AUTHOR]

In this paper, a microstrip patch antenna fed by a waveguide using an end-wall iris through ground plane has been modelled. The iris feed technique was proposed to overcome the narrow bandwidth problem of microstrip patch antenna. The iris is sized so that it is resonant and subsequently the antenna operates under the fusion of two modes relating to the iris and the patch, resulting in a wideband radiation characteristic with dual resonance. Measurement demonstrates the single bandwidth dual resonance type and the radiation bandwidth of (8 GHz-10.6 GHz). In order to show the impact of the iris feed technique on microstrip patch antenna's bandwidth, a comparison with some state-of-the-art works proposing various bandwidth enhancement techniques in the X-band is made. The proposed prototype, with a size of 1.76λ0×1.65λ0×1.29λ0, is more compact than several designs. It has a fractional bandwidth of 27.9%, thus it presents the prototype with the widest bandwidth with the simplest design fabrication. With regard to the electromagnetic modelling, this work is oriented towards the use of the hybrid MOM-GEC method in order to be able to perform a rigorous electromagnetic. It has been found that the MOM-GEC model is more efficient in terms of memory requirements and approximately four times faster than HFSS simulator software. [ABSTRACT FROM AUTHOR]

A novel elliptically slotted antenna (ESA), with two notched bands for Ultrawideband (UWB) applications, is presented. The ESA comprises of an elliptically slotted radiator with a beveled defected ground structure (DGS) for achieving UWB bandwidth ranging from 3.42 to 11.79 GHz (110%) for VSWR< 2. Two rejected bands at WLAN (5.02–5.97 GHz) and down link of X- band (7.23–7.72 GHz) applications are obtained by etching S-shaped slot in the microstrip feed line and an asymmetrical C- shaped parasitic stub above the DGS, respectively. The ESA is printed on FR-4 substrate with a compact size of 24 × 28 m m 2 and with a stable gain fluctuation from 2 to 4.08 dBi. A good matching, achieved in-between tested and simulated results, makes ESA to be a suitable candidate for WLAN/X-band-notched UWB applications. [ABSTRACT FROM AUTHOR]

An airborne radar echo signal includes signals returned from clutter and a target; thus, simulating the signal from the clutter may be crucial for predicting and analyzing accurate radar performance. Because it can be extremely difficult and expensive to obtain real measured signal data for various scenarios, an accurate signal generation method is required. Existing weather clutter and ground clutter simulators for an X-band airborne radar are combined to simulate the echo signal when two clutters exist simultaneously. The weather clutter effect becomes more significant with increasing frequencies, such as in the X-band. The proposed simulator can generate time-do- main signals by considering the random characteristics of the clutter signal and the Doppler effect caused by the movement of aircraft and clutter. In addition, a simple scheme is proposed for generating signals from artificial structures. Finally, the finite bandwidth of the transmitted chirp signal is calculated to improve the accuracy of the generated signal. [ABSTRACT FROM AUTHOR]

A novel low profile ultra-wideband antenna design has been presented in this work, that offers switchable band-notch characteristics suitable for both wideband and narrowband applications. The ultra-wideband characteristics (3.1–10.6 GHz) have been accomplished by using a unique elliptical shaped radiating structure, which is fed by a 50 Ω rectangular feedline and incorporating a defected ground structure that encompasses a pair of L-shaped slots and two rectangular slots for enhancing impedance matching performance. The proposed design has offered four notch-bands (Wi-Max, WLAN, X-band and C-band) that have been attained by using combinations of various types of slot structures in distinct parts of the proposed design along with a pair of split ring resonators. The reconfigurability among the desired notch-bands have been realized by configuring five switches in their ON/OFF states, which has resulted in a design apt for various narrowband applications. Antenna design optimization and performance evaluation has been carried out with the help of HFSSv13 tool. The performance of antenna has been assessed in terms of VSWR, gain and radiation patterns. The simulated and measured results have validated that antenna exhibits an operational UWB bandwidth from 3.1 to 10.6 GHz (with VSRW < 2) encompassing four notch-bands at 3.1–3.65 GHz (Wi-Max), 4.9–5.56 GHz (WLAN), 5.9–6.4 GHz (C-UPLINK) and 7.3–8.5 GHz (X-UPLINK). The profile size of the presented antenna (24 × 24 × 1.6 mm3) is appreciably compact and displays a fairly stable gain and radiation pattern characteristics for complete operational bandwidth except for four switchable notch-bands, making it suitable for wideband and narrowband applications. [ABSTRACT FROM AUTHOR]

In modern communication systems, dielectric resonator antennas (DRA) play an important role due to its several advantages over contemporary antennas. In this paper, novel flower-shaped multiple input multiple output (MIMO) DRA is proposed for wireless applications in X- band. The proposed antenna with four ports displays more than -15 dB isolation between ports with defected ground technique. The antenna exhibits 7.2-7.5 GHZ impedance bandwidth and 4.66 dBi gain at 7.3 GHz. MIMO performance parameters: Envelope Correlation Coefficient (ECC) and Diversity Gain (DG) of the proposed antenna are also studied and calculated. [ABSTRACT FROM AUTHOR]

This article presents a 2 × 2 printed planar array and its single element for weather‐monitoring (8.175–8.125 GHz) related applications. The proposed array's single antenna prototype is a nature‐inspired‐based design and is derived from natural Clover‐leaves. The single proposed element gives an appreciably decent gain and heavily suppresses cross‐polarization (x‐pol.) along its main beam direction. The array is designed using the Wilkinson divider‐based corporate feed network to achieve a low loss level and better bandwidth response. The sole fabricated element resonates at 8.19 GHz and offers 7.85 dBi peak gain and 336 MHz impedance bandwidth, respectively. Similarly, 12.30 dBi gain and 263 MHz impedance bandwidth have been achieved from the array geometry at the resonating frequency of 8.195 GHz. The prototypes' computed correction factor is 40.64 and 36.20 dB/m, respectively. Both the prototypes provide 100% bandwidth coverage for weather‐monitoring applications under X‐band. Both the prototypes provide a below −35 dB x‐pol. Along its main beam direction. They offer reasonably good radiation efficiency of 92.77% and 89.16%, respectively. An excellent agreement has been entrenched in between measured and simulated results of the prototypes. [ABSTRACT FROM AUTHOR]

A novel miniaturised single-layer square loop frequency-selective surface (FSS) designed and optimised for effective shielding in X-band is presented. The proposed FSS structure provides a wider bandwidth response of 4.0 GHz and it covers the X-band frequency (8–12 GHz) with a centre frequency of 10 GHz and attenuation of 39 dB. The proposed design compared the simulation results with equivalent circuit method results. Both achieved the same frequency response and bandwidth but the attenuation level is varied. Due to the symmetric structure, the proposed design achieves polarisation-independent characteristics and provides stable response at normal and oblique incidences for both TE and TM modes up to 60 ∘ . Both the measured and simulated results are in good agreement. [ABSTRACT FROM AUTHOR]

This paper presents the design and analysis of a miniaturized and novel wearable ultra-wideband (UWB) band-notch textile antenna for Body Area Networks (BANs). The major goal of building the antenna for wearable applications with band notch in X-band is to reject the downlink band (7.25 to 7.75 GHz) of satellite communication in the UWB frequency ranges of 3.1-10.6 GHz to keep away from interference. Computer Simulation Technology (CST) TM Microwave Studio, which is user-friendly and reliable, was used to model and simulate the antenna. The radiating element of the antenna is designed on Jeans' textile substrate, which has a relative permittivity of 1.7. The thickness of the jeans' fabric substrate has been considered to be 1 mm. Return loss, gain, bandwidth, impedance, radiation, and total efficiency, and radiation patterns are presented and investigated. The antenna is simulated placed on the three layers of the human body model, and the on-body results are summarized in comparison with free space. Results and analysis indicate that this antenna has good band-notch characteristics in the frequency range of 7.25 GHz to 7.75 GHz. The parametric study varying the relative permittivity of Jeans' fabric substrate of this antenna is also evaluated. In addition, effects on the antenna parameters of variation of ground plane size have been reported. The antenna is 25 mm × 16 mm × 1.07 mm in total volume. Results reveal that this antenna achieves the design goal and performs well both in free space and on the body. [ABSTRACT FROM AUTHOR]

in the last years the rapid development in the satellite communication and broadcasting systems require to develop a low cost, light Wight, easiness in movement and in usage antennas. That's capable of high performance at the same time. In this paper X-band micro-strip antenna has been discussed and designed which could be used for many applications and it is consist of radiating patch on a Roger RO4003C substrate with a ground patch, and the micro-strip feeding line to the patch is set on 50 Ohm. And it will give us 8.45 dB peak gain in X-band Frequency range and wide Impedance Bandwidth (IBW) range from 5.8 GHz till 12 GHz. [ABSTRACT FROM AUTHOR]

A coplanar waveguide (CPW) fed Eshaped patch antenna for X-band applications is presented in this paper. The proposed antenna consists of meandered slots on the main arm of Eshaped patch and occupies a size of 46×43 mm². The simulated resonating frequency is 10.01 GHz with reflection coefficient -31.03 dB and impedance bandwidth is 1400 MHz. The measured resonating frequency is also 10.01 GHz with reflection coefficient -43.41 dB and impedance bandwidth is about 1480 MHz. The bandwidth of the proposed antenna is improved compared to existing models due to usage of CPW. The measured and simulated results are in good agreement. [ABSTRACT FROM AUTHOR]

A simple circular patch antenna with notch ground and arc patch has been proposed in this paper. Antenna is fed with Coplanar Waveguide (CPW) feed. In this CPW feed, ground exists only on top of the substrate and either side of the feed strip. Ground is notched at either top corner to achieve multiband frequency. A small arc gap is created between the feed strip which is attached to arc patch and the circular radiating patch known as capacitive loading to achieve WLAN 5.2/5.8 GHz band. Antenna is fabricated on FR4 substrate having dimensions (40 mm x 30 mm x 1.6 mm). Relative dielectric constant of the substrate is 4.4. The proposed antenna covers multiple frequency bands with impedance bandwidth (S11 <-10 dB) of 20.4% from 2.2-2.7 GHz, 61% from 4.1-7.7 GHz, and 25.5% from 8.9-11.5 GHz. These operating bands are suitable for 2.4 GHz / 5.2 GHz / 5.8 GHz Wireless local area network (WLAN) bands and X-band applications. Effects of key design parameters such as radius of the patch and length and width of arc have been investigated. Return loss, VSWR, Radiation pattern, and gain characteristics of the antenna are investigated. Antenna exhibits positive gain and good radiation characteristics over these frequency ranges. There is a good agreement between the measured and simulation results. [ABSTRACT FROM AUTHOR]

A three-section coupled-cavity traveling-wave tube (CC-TWT) has been developed for avionic applications. The design parameters for a TWT operating in ${X}$ -band with a high average power, high power, high efficiency, high duty, wideband, low weight, and rugged structure have been obtained. Data presented show a good agreement between simulation results and prototype test results. The small-signal simulations were done with software developed in house for the evaluation of interaction impedance. The commercial code CST suite was used for the prediction of the dispersion diagram. The large-signal simulations were carried out with the “1-D code, computer program for analysis of CC-TWT,” by Cosmic. This paper explains the theory used for the design and shows the “cold test” and “hot test” results achieved with the prototype. The prototype has been able to deliver more than 1.5-kW average output power in a bandwidth larger than 1 GHz. [ABSTRACT FROM AUTHOR]

Abstract: This article presents the design and fabrication of a 6 W X‐band hybrid Class‐J power amplifier (PA) based on a bare die GaN on SiC HEMT by accurate implementing the transistor nonlinear capacitor effects. The transistor input capacitor is precisely modelled and its nonlinearity effects on Class‐J performance is studied for the first time. It is shown that the harmonic generation property of the nonlinear input capacitor, especially at the second harmonic, can be of benefit to shape the transistor gate voltage as a quasi‐half wave sinusoidal waveform and consequently, it can improve the power added efficiency (PAE). A complete 3D thermal model of the power transistor is developed using ANSYS software and it is calibrated based on the thermal measured data. The PA achieves 13 dB average power gain over the frequency range of 8.8‐9.6 GHz. The drain efficiency and PAE are about 67% and 58% at 9.2 GHz, respectively. [ABSTRACT FROM AUTHOR]

BiFeO 3 (BFO) multiferroic nanoparticles have attracted increasing attention owing to the coexistence of ferroelectric and ferromagnetic properties. In this work, Bi 1−x Mg x FeO 3 (x = 0.05, 0.1, 0.15) multiferroic nanoparticles were synthesized by the sol-gel method. The electromagnetic properties and microwave absorption performance in the temperature range of 323–723 K at X-band were investigated. The qualified bandwidth (absorption intensity < −10 dB) of the Mg-doped BFO materials covers the whole X-band at 673 K, suggesting promising candidates as high-temperature electromagnetic absorbers. [ABSTRACT FROM AUTHOR]

A novel carbon nanotube (CNT)-based rectangular microstrip antenna for wide impedance bandwidth applications has been designed and developed. The copper patch commonly placed on the substrate in a conventional rectangular microstrip antenna is replaced with a CNT patch prepared using spin coating. The MWCNT patch antenna was fabricated by spin coating method and it exhibits an increased impedance bandwidth of 20%. The enhancement of the impedance bandwidth does not affect the broadside radiation characteristics. The carbon nanotubes are highly conductive nanomaterial. Due to this unique property, each nanotube present on the surface resonates electromagnetic waves individually and influences the enhancement in the bandwidth. The simple design and fabrication of the proposed antenna can be employed for synthetic aperture radar applications. [ABSTRACT FROM AUTHOR]

In this paper, a novel compact dual-band textile printed slot antenna with partial ground plane is proposed. The substrate of the designed antenna is prepared from jeans fabric material while the patch and ground plane are made from copper tape. The proposed antenna offers an experimentally measured impedance bandwidth of 46 %, i.e. from 3.01 to 5.30 GHz and 41 %, i.e. from 8.12 to 12.35 GHz. The antenna is further characterized by a peak gain of about 5.7 dB and a comparatively stable radiation pattern in the useful band. The antenna is compact in size and useful for WiMax (3.25-3.85 GHz), WLAN (5.15-5.35 GHz) and X-band (8-12 GHz) applications. Also, a comparison of simulated results is discussed with the measured results of the fabricated prototype. [ABSTRACT FROM AUTHOR]

ABSTRACT The aim of this work is to design a low-profile Circularly Polarized Dielectric Resonator Antenna for the X-band frequency applications. With optimized design the proposed Cylindrical DRA (CDRA) fed by off-centered L shaped slot is showing characteristics of Circular Polarization in the proposed band. Two orthogonal arms of off-centered L shaped slot having different dimension excite the two TM01δ modes at 9.5 and 10.5 GHz, in addition both slots itself produce resonances nearly at 8.6 GHz. Combination of all these resonances is generating the nature of circular polarization near 9.5 GHz. Parametric study on designed antenna has been done in order to determine the effect of design parameters on the circular polarization. Axial Ratio bandwidth of 10.5% (1 GHz) and impedance bandwidth of 25% (2.3 GHz) at 9.5 GHz has been shown for single and simple feed low-profile CDRA. Prototype of optimized design has been fabricated for the validation and measured results have shown good agreement with simulated ones. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:996-1000, 2017 [ABSTRACT FROM AUTHOR]

This article focuses on the common problem of uncontrollable transmission zero (TZ) in X-band filter design. Using uniform impedance rectangular resonator (UIRR) to design an X-band filter always results in an unpredictable TZ on the low-frequency side of the passband, which greatly deteriorates the frequency selectivity of the filter performance. Electromagnetic coupling polarity analysis of the UIRR shows that the magnetic crosscoupling between nonadjacent resonators which is opposite to the main coupling plays a major role in the unpredictable TZ. By optimizing the UIRR from the loop structure with a small opening to the folded one, weak couplings between resonators are obtained. A high-temperature superconducting filter at X-band using folded UIRR resonator was designed and fabricated with a center frequency of 10.01 GHz and a bandwidth of 58 MHz, and the uncontrollable TZ has been removed successfully from the low-frequency side of passband. The measured insertion loss is less than 0.4 dB and the return loss is greater than 15 dB. [ABSTRACT FROM AUTHOR]

This paper demonstrates double bow-tie frequency selective surface (FSS) geometry for X-band applications with a bandwidth value of 1.82 GHz and Ku-band applications with a bandwidth value of 3.44 GHz. Throughout this study, parametric analyses of the proposed structure are also performed. Alterations in the reection and transmission characteristics of this specially designed structure by virtue of defined variables are analyzed. Those variables are determined by considering the geometric and material properties of the proposed structure. To analyze the reection and transmission coefficients, two different simulators, namely the High Frequency Structure Simulator (ANSYS HFSS), which is based on the finite element method (FEM), and the Computer Simulation Technology Studio Suite (CST Studio Suite), which is based on the finite integration method (FIM), are used. The structure is validated via those two solvers. Good agreement is obtained by both solvers, and the results are compared in terms of frequency, return loss, insertion loss, and fractional bandwidth. [ABSTRACT FROM AUTHOR]

In this paper Cylindrical Dielectric Resonator Antenna (CDRA) has been designed for X-band frequency range applications with slot feeding. Bandwidth of designed cylindrical dielectric resonator antenna has been enhanced by making the slot to be resonating and inserting very thin low permittivity dielectric layer between the slot and CDRA. Resonating slot excites the closely spaced HEM11δ and HEM21δ mode inside the antenna as well as provides the resonance at the upper side of desired X-band. Low profile low permittivity layer provides the excellent matching of these modes and shift the HEM21δ mode to higher frequency side at 11.25 GHz with better impedance matching. By combining all of three resonances, nearly 85 % increment in impedance Bandwidth has been obtained with reference to non resonating slot excited CDRA. Fractional impedance bandwidth for proposed design is 48 % and average Gain of 6 dB with more than 92 % radiation efficiency has been shown by the antenna throughout the desired band with broadside pattern. [ABSTRACT FROM AUTHOR]

ABSTRACT This letter presents the design, fabrication, and measurement of a broadband MEMS microwave phase detector for X-band, 8-12 GHz. In order to realize the broadband performance, a two-section power combiner is designed and utilized for the configuration of the phase detector. Stable sensitivities of phase detection are revealed by measurements within the bandwidth 8-12 GHz. The sensitivities are all better than 7.1, 22.1, 33.4, 42.0, and 51.2 mV/mW at 10, 50, 100, 150, and 200 mW input power, respectively. Moreover, the discrepancies are less than 1.8, 5.1, 7.3, 9.3, and 10.9 mV/mW at the above powers for different frequencies. The measured output voltage versus the phase difference at 200 mW, 10 GHz is normalized and compared to the theoretical value. The relative error is less than 8.5%. The response times of this presented phase detector are also obtained by measurement. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:806-809, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT This paper presents two narrowband high-temperature superconducting (HTS) filters at 10 GHz with a 0.6% fractional bandwidth. Uniform impedance rectangular resonator (UIRR) and stepped impedance H-type resonator (SIHR) are proposed to achieve HTS filters with high Q value, low sensitivity, weak coupling, and good parasitic response. A six-pole HTS filter that has UIRRs with a Q value of 17,700 is fabricated; this filter has a 19.9 dB return loss and a 0.38 dB insertion loss. An eight-pole HTS filter that has SIHRs with a Q value of 12,100 is also manufactured; this filter has a 12.2 dB return loss and a 0.64 dB insertion loss. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1516-1520, 2014 [ABSTRACT FROM AUTHOR]

A design procedure for asymmetric SPDT switches is proposed and validated by a MMIC demonstrator covering the full X-Band, well suited to integration in T/R modules. The demonstrator exhibits 0.7 dB and 1.6 dB insertion loss along its TX and RX paths, respectively, and 21.5 dB isolation in TX mode. Chip size is as compact as 1 x 1 mm². [ABSTRACT FROM AUTHOR]

Highlights: [•] We present a 1GHz DAC-board based home-built EPR spectrometer operating at X-band. [•] Supported by a fully customizable Python programming platform. [•] Highly precise phase (0.007°), amplitude (42dB), and delay (⩽250ps) resolution. [•] Demonstrates a transfer function correction to compensate for resonator bandwidth. [ABSTRACT FROM AUTHOR]

A narrow band radar system based on a field programmable gate array is proposed for dual-mode operation.Frequency-modulated continuous-wave (FMCW) radar mode is for short-range target detection and pulse-Doppler (PD) radar mode is for long-range target detection. Precomputed codes are used to generate linear frequency modulation signals in both FMCW and PD radar mode. The bandwidths of FMCW and PD radar modes are 10 and 1 MHz. Experiments have been carried out to confirm the system operation. In FMCW radar mode, nonlinear amplitude response can be corrected by precomputed code. In PD radar mode, the RX signals have been checked in the pulse width of 4 μs with a compressed echo signal response. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:474-479, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27343 [ABSTRACT FROM AUTHOR]

Abstract: This paper reports on the performance comparison of different structures of reflectarray resonant elements operating in X-band frequency range. A thorough investigation has been carried out in terms of reflecting area, surface current density, reflection loss, 10% bandwidth, reflection phase and Figure of Merit (FoM). Predicted results based on Finite Integral Method (FIM) demonstrate that rectangular patch element with widest reflecting area of 105.46mm2 and surface current density of 162A/m is shown to offer minimum reflection loss and static phase range of 0.23dB and 120° respectively, whereas triangular loop with a smallest reflecting area of 7.46mm2 and surface current density of 3925A/m exhibits maximum reflection loss and static phase range of 3.90dB and 190°. Moreover it has been shown that FoM value increases with an increase in static phase range performance. [Copyright &y& Elsevier]

A frequency independent dielectric resonator array (FIDRA) is designed and investigated experimentally for X-band applications.In this proposed array, nine rectangular shaped dielectric resonators are arranged in log periodic fashion to attain electrical characteristics which will vary insignificantly with frequency over the entire desired bandwidth. The resulted frequency independent array offers up to 56% wider impedance bandwidth with a VSWR less than two. The bandwidth achieved by proposed FIDRA covers a frequency range 6.3-11.2 GHz which is the desired frequency range for X-band applications in communication engineering. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:400-403, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27337 [ABSTRACT FROM AUTHOR]

A coplanar waveguide (CPW) fed ultra-wideband (UWB) antenna with dual notched band characteristics is" presented in this paper. The circular wide slot and circular radiation patch are utilized to broaden the impedance bandwidth of the UWB antenna. The dual notched band functions are achieved by employing two stepped impedance resonators (SIRs) which etched on the circular radiation patch and CPW excitation line, respectively. The two notched bands can be controlled by adjusting the dimensions of the two stepped impedance resonators which give tunable notched band functions. The proposed dual notched band UWB antenna has been designed in details and optimized by means of HFSS. Experimental and numerical results show that the proposed antenna with compact size o./'32 x 24 mm has an impedance bandwidth ranging from 2.8 GHz to 13.5 GHz for voltage standing-wave ratio (VSWR) less than 2, except the notch bands 5.0 GHz- 6.2 GHz for HIPERLAN/2 and IEEE 802.11a (5.1 GHz - 5.9 GHz) and 8. 0 GHz-9.3 GHz for satellite and military applications. [ABSTRACT FROM AUTHOR]

A X-band amplifier using microwave power has been developed for Wireless applications .Operating under a single power supply this one stage amplifier has 10 dB of typical gain for the entire 1.56 GHz bandwidth (9.44GHz - 11 GHz).This amplifier is designed for application of data and video transmission on AL2O3 _ Ceramic substrate of thickness of 0.635 mm and relative permittivity of 9.8. To maximize the performance of the amplifier this requires insert networks to adapt input and output of the amplifier with conjugate adaptation. Simulations with Ansoft Designer with the results obtained by inserting different networks to adapt at the input and the output of the transistor are different gain and bandwidth .A maximum gain of 10 dB is obtained with a bandwidth of 1.56 GHz with a triple open stub at the input and a symmetrical open stub at the output of the MESFET transistor. [ABSTRACT FROM AUTHOR]

A microstrip-fed ultra-wideband antenna with dual band-rejection characteristics is investigated. The antenna has the same shape between radiation patch and ground plane, and is fabricated on a Rogers RT/duroid 5880 substrate with an overall size of 22×31.85×0.508 mm3. To generate two notched frequency bands, a U-shaped parasitic element on the back of the patch is utilized. The two notched bands can be controlled by adjusting the size of the parasitic element. The measured results show that the proposed antenna has an impedance bandwidth of 3.0 to 11.7 GHz for S11<-10 dB, expects two eliminated frequency bands 5.08|5.96 GHz for wireless local area network and 8.71|10.25 GHz for X-band [ABSTRACT FROM AUTHOR]

This paper presents a wideband transformer-coupled CMOS power amplifier (PA). On-chip transmission-line transformers are used as key components of matching networks at output, input, and interstage. The wideband on-chip transformer is harnessed without any additional inductive devices so that a wideband power characteristic can be achieved. The PA is fabricated using a 0.18-\mu\ m CMOS process. It provides a saturated output power of 21.5 dBm with the power-added efficiency (PAE) of 20.3%, and the output 1-dB gain-compressed power (P1\ {dB}) is 20.2 dBm with the PAE of 14.8% at 9.5 GHz, respectively. The small-signal gain is 25.3 dB and the 3-dB bandwidth is 6.5 GHz (6.5–13 GHz). The die area is 1.34 mm \times 0.47 mm. Among the reported X/Ku-band CMOS PAs, this amplifier achieves the highest figure of merit, and also shows suitable performances for phased-array systems. [ABSTRACT FROM AUTHOR]

This paper reports a development of a narrowband high-temperature superconducting filter with both high selectivity and flat group delay. The filter has a center frequency of 8.625 GHz and a 3-dB bandwidth of 42 MHz (a fractional band- width of 0.49%). In order to achieve both high band-edge steepness and excellent group-delay flatness, we introduce a 14-resonator quasi-elliptic function response with three pairs of transmission zeros (one pair for high selectivity and two pairs for flat group delay) in the cascaded quadruplet coupling structure. We also develop a novel low radiation resonator (double-folded resonator) to reduce the parasitic coupling and meet other requirements for the 8-GHz filter. The filter was fabricated on a 2-in-diameter 0.5-mm-thick MgO wafer with double-sided YBCO films. The measured results show a midband insertion loss of 1.6 dB and a return loss better than 15.5 dB. Band-edge steepness reaches over 11.7 dB/MHz at both the high- and low-frequency edges. The 60-dB rectangle ratio is less than 1.25. The out-of-band rejection is over 70 dB at 5.98 MHz from the 3-dB band edge. The variation of group delay is less than 23 ns over 33 MHz (78.5% of 3-dB bandwidth), and less than 30 ns over 34.5 MHz (82% of 3-dB bandwidth). [ABSTRACT FROM AUTHOR]

An in situ tunable diode mounting topology for waveguide switches is presented and utilized to design and fabricate two evanescent-mode X-band switching modules of approximately 15% and 25% fractional bandwidth. The ability of the mounting topology to operate in a high-power environment is verified in an evanescent-mode X-band switch using six packaged p-i-n diodes, successfully reflecting 4 kW of pulsed power. [ABSTRACT FROM AUTHOR]

A consistent strategy for the design of finite array antennas consisting of differently sized radiating elements is discussed. In view of increasing the total bandwidth of the antenna system, while maintaining a low mutual coupling between the elementary radiators, sparse subarrays, operating at adjacent frequency ranges, are interleaved on a common (shared) aperture. The sparse architectures are designed using a combinatorial method that ensures an acceptable behavior in the side-lobes region in conjunction with a narrow beamwidth. The effect of the mutual coupling between identical and differently sized elements is accurately evaluated and is accounted for in predicting the performance of each individual radiator. The concept is illustrated by designing a shared aperture antenna consisting of two interwoven subarrays that jointly cover a fractional bandwidth of 14% in the X-band. Cavity-backed, stacked-patches antennas with coaxial feeding are used as elementary radiators. [ABSTRACT FROM PUBLISHER]

• A compact size antenna with dimensions 10 mm × 10 mm × 1.6 mm. • Exhibits dual band at 9.7 and 11.4 GHz which covers X-band applications. • Considerable gain, better directivity and wide bandwidth. • The computed efficiency is 83% at 9.7 GHz and 69% at 11.4 GHz. • Finite element technique based HFSS 19 has been used for optimization. In this manuscript, a novel Circular Ring Resonator (CRR) defected ground structure has been proposed for X-band applications. The proposed structure uses inset feed modified square ring as the radiating layer, two concentric circular conductive copper rings as Defected Ground Structure (DGS) over a lossy Flame Retardant-4 substrate dielectric material. This DGS is an emerging technique which is used for enhancing the various parameters of patch antennas. The dimensions of the radiating element are 0.3λ × 0.3λ × 0.04λ at first resonating frequency and exhibits impedance bandwidth for S 11 < −10 dB at 9.7 and 11.4 GHz which is useful for military radar and satellite terrestrial communications. Finite element technique based HFSS 19 has been used for simulation. [ABSTRACT FROM AUTHOR]

This article presents a 10-pole high-temperature superconducting (HTS) wideband microstrip bandpass filter with a novel configuration and compact size.The filter at 10 GHz with a fractional bandwidth of 40% is designed and fabricated on a 32.6 mm × 6.7 mm × 0.5 mm MgO substrate with double-sided YBCO films. The internal couplings between quarter-wavelength resonators are realized by parallel-coupled microstrip line (PCML) structure and capacitive open-ended stubs. The strong external couplings required by wideband filter are realized by impedance steps and capacitive stubs. The measured results at 55 K, without any tuning, show a high performance. The insertion loss is less than 0.31 dB, the return loss is better than −14 dB, and the out-of-band rejection is higher than 70 dB. The overall measurements are in good agreement with the simulations. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1027-1029, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27485 [ABSTRACT FROM AUTHOR]

A three-stage 7- to 14-GHz monolithic low-noise amplifier (LNA) has been fabricated using 0.15-μm AlGaAs/GaAs pHEMT technology.To achieve ultra low noise figure and wide operation bandwidth, the proposed LNA uses wideband matching network and negative feedback technique. Measured results from 7 to 14 GHz demonstrate a minimum of 1.1 dB noise figure and 26 dB gain. The input and output return loss exceeded 10 dB across the band. These results demonstrate the best performance of AlGaAs/GaAs pHEMT technology for wideband and low noise applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2615–2617, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25547 [ABSTRACT FROM AUTHOR]

Experimental results on two GaAs PHEMT MMIC Class F Power Amplifiers for X-band applications are reported, aimed to validate a novel devices' combination method. In particular, 28.1 dBm output power with 44% power added efficiency and 30.6 dBm output power with 40% of power added efficiency were measured at 9.6 GHz, for single and combined devices amplifiers respectively. Both realised amplifiers exhibit 12% operating bandwidth. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 360–362, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22141 [ABSTRACT FROM AUTHOR]