Via-less CRLH-TL unit cells loaded compact and bandwidth-enhanced metamaterial based antennas

The via-less composite right hand left hand (CRLH)-TL unit cells loaded compact and bandwidth-enhanced metamaterial (MTM) antennas have been designed and experimentally investigated. Four novel unit cells are designed and its dispersion characteristics of the proposed unit cells are numerically calculated which follows CRLH-TL properties. Further, the conventional metallic vias of CRLH-TL have been eliminated to increase the fabrication flexibility. The four CRLH-TL unit cells are loaded into monopole antennas which result, four via-less open-ended MTM antennas respectively. Its ZOR (zeroth order resonance) bandwidth is increased by realizing small shunt capacitance and large shunt inductance. Further, to increase overall antenna bandwidth, merging of ZOR mode to the higher and lower order modes into a single pass band has been done by realizing proper CRLH-TL unit cells. The each proposed antenna has a dimension of 0.13λ₀ × 0.08λ₀ × 0.0085λ₀, where the free space wavelength λ₀ at 1.6 GHz. The four proposed antennas have S₁₁ < −10 dB fractional bandwidths (FBW) 173% (1–13.6 GHz), 169% (1.2–14.5 GHz), 158% (1.6–13.5 GHz) and 158% (1.6–13.5 GHz) respectively. The optimum gain and desired radiation characteristics have been obtained for all proposed antennas, which can be suitable for UWB applications. The CST-MWS has been used for the parametric study of the proposed antennas. A good agreement has been observed between simulated and experimental results.     

Wheel shaped modified fractal antenna realization for wireless communications

A compact, low profile circular fractal patch antenna with low latency, low cost, high speed and multiband is presented. With the help of CST Microwave Studio Suite TM the proposed structure has been designed and analyzed. The simulated results are fixed experimentally. The suggested antenna has dimension of 32 × 36 mm² (W × L) and operating from 2.93 GHz–9.53 GHz with VSWR ≤ 2. The aerial is assembled on FR-4 (ε_r = 4.4) substrate with a thickness of substrate 1.25 mm. Detailed parametric studies of the antennas have been carried out. This microstrip fed antenna is suitable for ultra wideband (UWB), S, C and part of the X band applications.     

A printed monopole ellipzoidal UWB antenna with four band rejection characteristics

An antenna design with four band rejection characteristics for UWB application is demonstrated. The proposed unique UWB antenna has shape of an embedded ellipse at top of trapezoidal patch (named as ellipzoidal), 50 Ω impedance microstrip line feed and a truncated beveled ground plane. To realize four band stop characteristics, three inverted U-shaped and a single I-shaped slots each of half guided wavelength are utilized on radiating element. The fabricated antenna has dimensions of 27 mm × 36 mm × 1.6 mm. This four band notched ellipzoidal UWB antenna has measured frequency bandwidth 2.8–14 GHz for magnitude of S₁₁ < −10 dB level. The measured ellipzoidal antenna exhibits four band rejection characteristics for magnitude of S₁₁ > −10 dB at 3.55 GHz for WiMAX band (3.26–3.9 GHz), 4.55 GHz for ARN band (4.35–5.05 GHz), 5.7 GHz for WLAN band (5.5–6.65 GHz) and 8.8 GHz for ITU-8 band (7.95–9.35 GHz). The proposed ellipzoidal UWB antenna maintains omnidirectional radiation pattern, gain, linear phase response, <1 ns group delay, and transfer function in the whole UWB operating bandwidth except at notched frequency bands.     

Miniaturized active stepped impedance planar inverted-F antenna using common ground

This paper presents a compact active integrated antenna (AIA) comprising of class-A power amplifier (PA) and stepped impedance planar inverted-F antenna (PIFA). In the proposed design, a common ground is used for both PA and PIFA, resulting a compact antenna of size 0.14λ₀ × 0.11λ₀ × 0.01λ₀ (λ₀ is free space wavelength at 0.85 GHz). Moreover, it is demonstrated that by using the stepped impedance radiator the operating frequency of the active PIFA is shifted down from its natural resonant frequency of 1.36 GHz to 0.85 GHz, offering an extensive size reduction of 80%. This active integration increases the passive antenna gain through the effective loading of the antenna to the power amplifier. The measured result indicates that the active and passive antennas achieved the gain of 15.7 dB and 3.81 dBi, respectively after the integration. In addition, the maximum SAR value of antenna is found to be 0.64 W/kg.     

A miniaturized Vivaldi antenna by loading with parasitic patch and lumped resistor

A miniaturized Vivaldi antenna is presented in the paper. On the basis of original antenna, the miniaturized Vivaldi antenna applies parasitic patch and lumped resistor to improve impedance characteristics. The proposed load can expand the lower operating frequency to 1.96 GHz without changing antenna dimensions. The size of antenna is set as 43 × 40 mm². This size is about 0.28λ_L × 0.26λ_L, where λ_L is the free space wavelength at 1.96 GHz. The loaded Vivaldi antenna is fabricated and measured. The simulated and measured results clarify the viability and effectiveness of the proposed design. The measured impedance bandwidth (VSWR ≤ 2) is from 2 GHz to more than 18 GHz. In addition, the measured radiation patterns and a peak gain between −1 and 9 dB can be obtained in the band of 2–18 GHz.     

Compact circular-patch-based bandpass filter for ultra-wideband wireless communication systems

Ultra-wideband (UWB) is a radio technology that enables low-power-level, short-range, and wide-bandwidth communication, and it has been widely applied in personal area networks, precision geolocation, medical, surveillance, and vehicular radar systems. Since Federal Communications Commission released the unlicensed use of the UWB range (3.1–10.6 GHz), a significant attention has been paid to the development of UWB devices, particularly UWB bandpass filters. In this paper, we propose a novel UWB bandpass filter based on circular patch resonator that is grounded by via and perturbed by slits and defected ground structures. The resonator’s behaviour is analysed in detail and it is shown that its specific configuration allows a flexible control of the three lowest resonant modes, which are used to form UWB passband. To demonstrate the potential of the resonator, a UWB filter has been designed, fabricated, and measured. The filter is characterized by the insertion loss lower than 1 dB and return loss higher than 17 dB within the passband, as well as by very small group delay variation of only 0.07 ns. Also, the filter exhibits suppression higher than 19 dB up to 30 GHz, and very small overall dimensions of only 0.31λ_g × 0.31λ_g, and thus it outperforms other published UWB filters.     

A modified ground apollonian ultra wideband fractal antenna and its backscattering

This paper presents the design of a modified ground apollonian ultra wideband (UWB) fractal antenna. The printed fractal antenna has been designed on a substrate with dielectric constant ?_r = 4.3 and thickness h = 1.53 mm. The antenna has been fabricated with optimized dimension and tested. The experimental result of this antenna exhibits UWB characteristics from frequency range 3 GHz to 18 GHz. This corresponds to 142.86% impedance bandwidth with center frequency of 10.5 GHz. The experimental radiation patterns of this antenna are nearly omni-directional in H-plane and bidirectional in E-plane. The effect of various design parameters on UWB characteristics have also been analyzed using a 3D electromagnetic simulator based on FEM method. The simulated and experimental results are in good agreement. The backscattering RCS of this UWB fractal antenna is better than ?31 dB throughout the FCC band (3.1 GHz to 10.6 GHz). The proposed coplanar waveguide feed appollian fractal antenna can be easily integrated with radio-frequency/microwave circuitry with low-manufacturing cost and useful for UWB applications.     

Corrugated SIW K band horn antenna

In the recent years, the strong demand for high performance, low cost and high gain antennas for telecommunication, surveillance, and imaging applications has rapidly grown at microwave and higher frequencies. High speed wireless links require modular, compact size and high directivity with low cross polarization antennas. To demonstrate the proposed concepts and design features, in this paper, a substrate integrated waveguide (SIW) feeding technique has been created having well behaved gain and suitable −10 dB bandwidth from 23.8 GHz to 25.7 GHz (roughly 2 GHz bandwidth), while the impedance bandwidth for VSWR < 2.5 is nearly 3 GHz. The simulated antenna attains 12.5 ± 1 dB gain over majority of K band with an occupied size of 82 mm × 40 mm × 2.54 mm and has roughly 95% radiation efficiency. The proposed antenna is an excellent candidate for integrated low cost K band and even higher frequency systems. The simulations are done by two full wave packages i.e. ANSYS HFSS and CST MWS that associated with finite element method (FEM) and finite difference time domain (FDTD), respectively. The results show good agreements between these two methods.     

Design,fabrication and measurement of triple band frequency reconfigurable antennas for portable wireless communications

In this paper two triple-band monopole antennas are proposed for portable wireless applications such as WiFi, WiMAX and WLAN. Two different geometrical structures are used for the radiating elements of these antennas, each printed on a low cost FR-4 substrate. Truncated metallic copper ground is used to attain optimum radiation pattern and better radiation efficiency. The frequency of the antennas is reconfigured using a lumped-element switch. The proposed antennas covers three frequency bands 2.45, 3.50 and 5.20 GHz depending upon the switching conditions. Both antennas works with an optimum gain (1.7–3.4 dB), bandwidth (6–35%), VSWR (<1.5) and radiation efficiency (85–90%). Due to its affordable size (1.6 × 35 × 53 mm³), the antennas can be used in modern and portable communication devices such as laptops, iPads and mobile phones. The prototype of the antennas are fabricated and the measurements and simulations are found in close agreement.     

Dual band monopole antenna based on metamaterial structure with narrowband and UWB resonances with reconfigurable quality

In this article, an Ultra Wide Band (UWB) monopole antenna based on Metamaterial (MTM) unit cell with reconfigurable feature has been developed. The proposed antenna covers 3.1–10.6 GHz for UWB applications and it has a reconfigurable narrow-band for L-band (1.27 GHz) and wireless applications. The gaps in Split Rings Resonator (SRR) element are made for the Left-hand capacitance and Ω-shape strip layer by four via junctions are used for Left-hand inductance. The antenna is printed on FR-4 low cost substrate with relative permittivity of 4.4 and thickness of 1.6 mm. The total size of the antenna is 40 mm × 40 mm. The simulation is carried out using HFSS commercial full-wave software. In addition, the experimental results are presented and compared with simulated results. The antenna gives a maximum peak gain of 6 dBi with Omni-Directional radiation pattern and high efficiency of more than 70%. By embedding four switches in Ω-shape strip layer, a reconfigurable antenna has been successfully designed for wireless applications with sufficient qualification. The monopole part covers the UWB spectrum and the CRLH is responsible for the controllable narrowband resonance. The simulation and experimental results are confirmed by the numerical results.     

Design and analysis of implantable CPW fed bowtie antenna for ISM band applications

A novel implantable coplanar waveguide (CPW) fed crossed bowtie antenna is proposed for short-range biomedical applications. The antenna is designed to resonate at 2.45 GHz, one of the industrial-scientific-medical (ISM) bands. It is investigated by use of the method of moments design equations and its simulation software (IE3D version 15). The size of the antenna is 371.8 mm³ (26 mm × 22 mm × 0.65 mm). The simulated and analyzed return losses are −23 and −25 dB at the resonant frequency of 2.45 GHz. We have analyzed some more performances of the proposed antenna and the results show that the proposed antenna is a perfect candidate for implantation. The proposed antenna has substantial merits like low profile, miniaturization, lower return loss and better impedance matching with high gain over other implanted antennas.     

Auxiliary components for kilopixel transition edge sensor arrays

We have fabricated transition edge sensor bolometer focal plane arrays sensitive to mm-submillimeter (0.1–3 THz) radiation for the Atacama Cosmology Telescope (ACT), which will probe the cosmic microwave background at 145, 215, and 280 GHz. Central to the performance of these bolometers is a set of auxiliary resistive components. Here we discuss shunt resistors, which allow for tight optimization of bolometer time constant and sensitivity. Our shunt resistors consist of AuPd strips grown atop interdigitated superconducting MoN_x wires. We can tailor the shunt resistance by altering the dimensions of the AuPd strips and the pitch and width of the MoN_x wires and can fabricate all of the shunts necessary for a kilopixel focal plane bolometer array on a single 4″ wafer. By modeling the resistance dependence of these parameters, a variety of different 0.75 ± 0.05 mOhm shunt resistors have been fabricated. This variety includes different shunts which have MoN_x wires with wire width equal to 1.5 and 10 μm and pitch equal to 4.5 and 26 μm, respectively. Our ability to set the resistance of the shunts hints at the scalability of our design. We have also integrated a SiO₂ capping layer into our shunt resistor fabrication scheme, which inhibits metal corrosion and eventual degradation of the shunt. Consequently, their robustness coupled with their high packing density makes these resistive components attractive for future kilopixel detector arrays.     

Dual-resonance concurrent oscillator

This paper studies a new dual-band CMOS class-C voltage-controlled oscillator (VCO). The oscillator consists of a dual-resonance LC resonator in shunt with two pairs of capacitive cross-coupled nMOSFETs. The proposed oscillator has been implemented with the TSMC 0.18 μm CMOS technology, and it shows a frequency tuning range with two frequency bands and a small tuning hysteresis is measured. The oscillator can generate differential signals at 2.4 GHz and 6.9 GHz and it also can generate concurrent frequency oscillation while the circuit is biased around the bias with frequency tuning hysteresis. With the supply voltage of V_DD = 1.1 V, the VCO-core current and power consumption of the oscillator are 2.90 mA and 3.19 mW, respectively. The die area of the class-C oscillator is 0.9 × 0.97 mm². Overvoltage stress is applied to the oscillator, measurement indicates the concurrent oscillation is sensitive to overvoltage stress.     

A novel low power UWB cascode SiGe BiCMOS LNA with current reuse and zero-pole cancellation

A low power cascode SiGe BiCMOS low noise amplifier (LNA) with current reuse and zero-pole cancellation is presented for ultra-wideband (UWB) application. The LNA is composed of cascode input stage and common emitter (CE) output stage with dual loop feedbacks. The novel cascode-CE current reuse topology replaces the traditional two stages topology so as to obtain low power consumption. The emitter degenerative inductor in input stage is adopted to achieve good input impedance matching and noise performance. The two poles are introduced by the emitter inductor, which will degrade the gain performance, are cancelled by the dual loop feedbacks of the resistance-inductor (RL) shunt–shunt feedback and resistance-capacitor (RC) series–series feedback in the output stage. Meanwhile, output impedance matching is also achieved. Based on TSMC 0.35 μm SiGe BiCMOS process, the topology and chip layout of the proposed LNA are designed and post-simulated. The LNA achieves the noise figure of 2.3–4.1 dB, gain of 18.9–20.2 dB, gain flatness of ±0.65 dB, input third order intercept point (IIP₃) of ?7 dBm at 6 GHz, exhibits less than 16 ps of group delay variation, good input and output impedances matching, and unconditionally stable over the whole band. The power consumption is only 18 mW.     

On the performance of the 2D planar metamaterial structure

The performance of a 2D metamaterial (MTM) structure using finite element method (FEM) and transmission line model (TLM) is investigated in this paper. The size of the proposed unit cell is 4 mm × 4 mm to resonant around 12 GHz. The unit cell is constructed from a patterned patch and solid ground plane that are connected with via through an FR-4 substrate. The unit cell is characterized from 11 GHz to 14 GHz in terms of S-parameters, effective refractive index, and dispersion properties. It is found that the proposed unit cell behaves like unbalanced case of a passive constant k band elimination filter. Moreover, it is found that the unit cell exhibits no negative refractive index (NRI) over a wide range of frequencies; however, it shows a less than 1 refractive index over then same frequency range. A theoretical investigation based on TLM is developed to extract the values of the basic lumped, RLC, elements network.     

Broadband proximity fed ring microstrip antenna arrays

Various gap-coupled array configurations of ring microstrip antennas and rectangular slot cut ring microstrip antennas with proximity fed slot cut ring microstrip antenna for larger bandwidth and gain are proposed. The rectangular slot in ring patch reduces its orthogonal TM₀₁ and TM₀₂ mode resonance frequencies and along with TM₁₀ modes of fed and parasitic ring patches, yields broadband response. The gap-coupled configuration with ring patch and slot cut ring patch yields bandwidth of nearly 430 MHz with broadside radiation pattern and peak gain of more than 9 dBi. By gap-coupling ring patches along all the edges of proximity fed pair of slot cut ring patch, a 3 × 3 ring microstrip antenna array is realized. It yields bandwidth of more than 460 MHz with peak gain of more than 10 dBi. To further improve upon the bandwidth, a 3 × 3 array of ring patches in which rectangular slot is first cut on the edges of ring patch which are gap-coupled along x-axis and further cut inside the patches which are gap-coupled along x and diagonal axes, is proposed. Both of these configurations yield bandwidth of more than 500 MHz (>45%) with a peak gain of around 10 dBi.     

Hexagonal boundary Sierpinski carpet fractal shaped compact ultrawideband antenna with band rejection functionality

In this paper a second iteration Sierpinski carpet fractal shape UWB antenna with hexagonal boundary is presented. The antenna covers the frequency band from 3 GHz to 12 GHz (VSWR ≤ 2). The proposed antenna has the capability to reject 5.15–5.825 GHz band assigned for IEEE802.11a and HIPERLAN/2 which is achieved by embedding a ‘Y’ shaped slot in the radiator that extends to the central conductor of the CPW feed as well. A fabricated prototype is developed where the simulation and experimental results are in good agreement. Measured peak antenna gain varies from 1.25 dBi to 6 dBi within the band. The proposed antenna has a compact size of 33 mm × 32 mm that includes the substrate around the radiating element. Time domain characteristic reveal that the antenna is non-dispersive with a variation of measured group delay within 0.5 ns over the entire band.     

DC and microwave characteristics of Lg 50 nm T-gate InAlN/AlN/GaN HEMT for future high power RF applications

The DC and microwave characteristics of L_g = 50 nm T-gate InAlN/AlN/GaN High Electron Mobility Transistor (HEMT) on SiC substrate with heavily doped n+ GaN source and drain regions have demonstrated using Synopsys TCAD tool. The proposed device features an AlN spacer layer, AlGaN back-barrier and SiN surface passivation. The proposed HEMT exhibits a maximum drain current density of 1.8 A/mm, peak transconductance (g_m) of 650 mS/mm and ft/fmax of 118/210 GHz. At room temperature, the measured carrier mobility, sheet charge carrier density (n_s) and breakdown voltage are 1195 cm²/Vs, 1.6 × 10¹³ cm⁻² and 18 V respectively. The superlatives of the proposed HEMTs are bewitching competitor for future monolithic microwave integrated circuits (MMIC) applications particularly in W-band (75–110 GHz) high power RF applications.     

Impact of high-k gate dielectric on analog and RF performance of nanoscale DG-MOSFET

Now a days, high-k dielectrics have been investigated as an alternative to Silicon dioxide (SiO₂) based gate dielectric for nanoscale semiconductor devices. This paper is an attempt to characterize the analog and RF performance of the high-k metal gate (HKMG) double gate (DG) metal oxide semiconductor field effect transistor (MOSFET) in nanoscale through 2-D device simulation. The results demonstrates the impact of high-k oxide layer as single and gate stack (GS). The key idea behind this investigation is to provide a physical explanation for the improved analog and RF performance exhibited by the device. The major figures of merit (FOMs) studied in this paper are transconductance (g_m), output conductance (g_d), transconductance generation factor (g_m/I_D), early voltage (V_EA), intrinsic gain (A_V), cut off frequency (f_T), transconductance frequency product (TFP), gain frequency product (GFP) and gain transconductance frequency product (GTFP). The effects of downscaling of channel length (L) on analog performance of the proposed devices have also been presented. It has been observed that the performance enhancement of GS configurations (k=7.5 i.e device D5 in the study) is encouraging as far as the nanoscale DG-MOSFET is concerned. Also it significantly reduces the short channel effects (SCEs). Parameters like DC gain of (91.257 dB, 43.436 dB), nearly ideal values (39.765 V⁻¹, 39.589 V⁻¹) of TGF, an early voltage of (2.73 V, 16.897 V), cutoff frequency (294 GHz, 515.5 GHz) and GTFP of (5.14×10⁵ GHz/V, 1.72×10⁵ GHz/V) for two different values of V_DS=0.1 V and 0.5 V respectively are found to be close to ideal values. Analysis shows an opportunity for realizing high performance analog and RF circuits with the device proposed in this paper i.e. device D5.     

Low power high gain CMOS LNA based on inverter cell and self-body bias for UWB receivers

A low-power low-noise amplifier (LNA) utilized a resistive inverter configuration feedback amplifier to achieve the broadband input matching purposes. To achieve low power consumption and high gain, the proposed LNA utilizes a current-reused technique and a splitting-load inductive peaking technique of a resistive-feedback inverter for input matching. Two wideband LNAs are implemented by TSMC 0.18 μm CMOS technology. The first LNA operates at 2–6 GHz. The minimum noise figure is 3.6 dB. The amplifier provides a maximum gain (S₂₁) of 18.5 dB while drawing 10.3 mW from a 1.5-V supply. This chip area is 1.028×0.921 mm². The second LNA operates at 3.1–10.6 GHz. By using self-forward body bias, it can reduce supply voltage as well as save bias current. The minimum noise figure is 4.8 dB. The amplifier provides a maximum gain (S₂₁) of 17.8 dB while drawing 9.67 mW from a 1.2-V supply. This chip area is 1.274×0.771 mm².