GHz Wireless Applications Research Articles

Liquid‐metal‐disk‐loaded monopole antenna based on 3D printed technique

A 3D printed disk-loaded monopole antenna by injecting liquid metal alloy is designed. The monopole antenna is operating at 2.4 GHz for wireless sensor network applications. The proposed antenna mainly comprises three parts: a hollow dielectric shell, liquid metal alloy, and a feeder. The hollow dielectric shell is fabricated by 3D printing technique. Liquid metal alloy EGaIn is filled in the hollow dielectric shell to form the antenna radiator. An SMA connector with square flange is inserted into the hollow dielectric shell to feed the antenna. A prototype antenna is fabricated and experimentally measured for verification. Measured results show that the frequency of the designed antenna covers from 2.36 to 2.6 GHz, which is suitable for commercial 2.4 GHz wireless communication applications.

Analysis of Different Feeding Techniques of Butterfly-Shaped Patch Antenna with Defected Ground for UWB Application

A miniaturized butterfly-shaped microstrip patch antenna is proposed for unlicensed millimeter wave band applications. The overall dimensions of the proposed antenna are (20 × 18 × 1.6) mm3 or (3.93 × 3.54 × 0.314)λ0 3 with rectangular defected ground structure, which is etched on the ground plane to improve its performances. This configuration achieved an ultra-wide bandwidth (UWB) of 7 GHz (26%) and 22 GHz (37.9%) with radiation efficiencies of 92% and 61%, covering the frequency range from 19.3–25.2 GHz to 48–70 GHz, respectively. The reflection coefficient of the antenna is −41.2 dB with a peak gain of 12.4 dBi at the 56.6 GHz and 10 dBi at 61.4 GHz resonating frequency. Further, the analysis of the proposed antenna is done by different feeding techniques like coaxial, inset feed, gap coupled, aperture coupled and proximity coupled. Considering the size, bandwidth and gain, the microstrip antenna is applicable for unlicensed 57–64 GHz wireless applications for the short-range and high-speed communications like WPAN, WLAN, Intelligent Transport System, Smart Automobiles and Gi-fi. All the simulation results have been performed on Ansys HFSS v.13.1. Proposed antenna has been fabricated on the PCB board.

Employment of mixed mode in single-layer microstrip antenna for ISM/WiMAX/WLAN/4G/Sub 6 GHz 5G mobile communication

ABSTRACTThe design and development of multiband antenna for useful operating bands are the current state-of-the-art research in the field of antenna research. A simple and single-layer printed multiband radiation structure eliminates the packaging complexity of modern communication devices. The present investigation proposes such simple and single-layer multiband antenna for ISM 2.5 GHz/WiMax 3.5 GHz/WLAN 5.2 GHz/ISM 5.8 GHz wireless application for 4G LTE and sub 6 GHz 5G spectrum. The proposed antenna can completely cover the required frequencies with good radiation characteristics at the broadside direction. The design has been carried out using the RT duroid 5870 substrate (ϵr = 2.33, height h = 1.575 mm) for simulation and measurements. In the proposed patch antenna, the slots have been judiciously used to employ mixed modal behaviour which capitulates multiple useful bands with proper bore-sight radiation.

Dual band circular polarized bow tie slotted patch antenna over high impedance surface for WiMAX application

AbstractA novel planar dual-band bow-tie slotted patch antenna backed by high-impedance surface (HIS) is designed at 2.5 and 3.5 GHz for wireless application. The antenna employs coplanar waveguide fed patch and bow-tie slot as radiating elements. The bow-tie slot enables dual-band operation for the antenna. The HIS is made asymmetric in design to make it polarization dependent. This polarization-dependent HIS is eventually designed to reflect circularly polarized waves from linearly polarized incident waves.

Design and optimization of a CMOS power amplifier using innovative fractional-order particle swarm optimization

In this paper, a new optimization algorithm is proposed to design and optimize a CMOS power amplifier at the frequency of 2.4 GHz for wireless applications in TSMC 0.18μm with respect to stability. In this new algorithm which is denoted as Hunter-Attack Fractional-order Particle Swarm Optimization (HAFPSO) algorithm, two main weaknesses of the classic Particle Swarm Optimization (PSO), i.e. trapping in local optima (stagnation) and the slow convergence rate are resolved. In the proposed algorithm, using the fractional-order derivatives, the particle convergence rates accelerate to the optimal solution. In addition, Hunter-attack strategy is used to avoid stagnation in classic PSO. In order to investigate the performance of the HAFPSO optimization algorithm, fifteen computationally expensive benchmark optimization problems are utilized. The results of experiments show the significant performance of the proposed algorithm in comparison with seven other well known optimization algorithms i.e GA, PSO, HFPSO, CLPSO, PSOGSA, GAPSO and FPSO. A statistical test procedure is also exploited to show significant difference performance of proposed algorithm from other optimization algorithms. The power amplifier is designed using HAFPSO, GA and two PSO-based optimization algorithms, i.e. classic PSO and Fractional-order PSO (FPSO). The results show the improvement of 50% of in PAE of the power amplifier.

Amplifier type active antenna at 2.45 GHz for wireless applications

In this paper, an active antenna is proposed, where microwave amplifier is directly integrated on passive antenna. The amplifier provides required RF power to the antenna, hence improves the system efficiency. This paper presents a slotted patch antenna, resonating at 2.45 GHz for Industrial Scientific Medical band, having excellent return loss of − 30 dB and radiation efficiency of 100%. The microwave amplifier was designed and optimized on AWR Microwave Office software for 11 dB gain and noise figure less than 2 at the frequency of 2.45 GHz. The proposed amplifier type active antenna was designed using FR4 substrate with substrate height, 1.6 mm and dielectric constant of er = 4.4. In active antenna, amplifier provides extra power to the antenna while electric parameters of active antenna are same, such as return loss is − 21.95 dB at 2.11 GHz and the improved bandwidth of 125 MHz. The passive antenna is designed, analyzed and optimized on IE3D Zeland software version 15.30.

Multi-cut four-port shared radiator with stepped ground and diversity effects for WLAN application

AbstractA four-port shared radiator is proposed for 5.2 GHz wireless application using multiple-cut rectangular geometry and partially stepped ground. The difficulty in making the shared radiator structure is almost removed in the presented design, and without the help of any isolating structure, sufficient value of isolation is achieved. The proposed shared geometry produces isolation of >10 dB in the 4.96–5.5 GHz operating frequency band. The gain of the MIMO antenna varies from 2.4 to 5.5 dBi, and radiation efficiency is >63% in the proposed band. The ports are arranged in an orthogonal manner to reduce the mutual coupling. An envelope correlation coefficient is <0.03 in the proposed antenna band. The total active reflection coefficient bandwidth of the antenna is 500 MHz with best combination of input excitation angles of 90, 180°. The isolation in the proposed shared radiator is enhanced by creating multiple cuts and stepped ground. To check the suitability of antenna for indoor and outdoor environments the mean effective gain and specific absorption rate results are also presented in the paper and it found under the required safety norms as per the international telecommunication union for uniform and Gaussian environments.

CPW-fed electrically small open-ended zeroth order resonating metamaterial antenna with dual-band features for GPS/WiMAX/WLAN applications

This paper gives the description of an electrically small (ka = 0.46 < 1) and low profile (0.007 λo) coplanar waveguide (CPW)-fed open-ended zeroth order resonating (ZOR) dual-band metamaterial (MTM) antenna. This MTM antenna is mainly composed of CPW-fed rectangular patch, small square metallic patches, semi-circular patch, and meander line inductor connected to CPW ground plane. The patches form a series inductor, the gap between them refers to the series capacitor, meander line inductor denotes shunt inductor whereas the capacitance between signal line and ground is modeled by shunt capacitor, thus exhibiting composite right/left-handed (CRLH) transmission line (TL). The design produces three resonant bands; first is because of zeroth order mode (n = 0) and the second and third are due to combined effects of coupling between patch and ground plane; and meander line inductor and the ground plane. The measured zeroth-order resonance (ZOR) occurs at 1.22 GHz. The bands due to coupling merge to create a wideband from 4.88 GHz to 7.24 GHz. The radiating unit cell size of the given antenna is 0.07 λo × 0.12 λo × 0.007 λo and the overall size is 0.08 λo × 0.12 λo × 0.007 λo at 1.22 GHz. The measured impedance bandwidths are 3.28% and 38.9% and measured gain is 0.99 dBi and 3.72 dBi for the first and second band respectively. The simulated results are verified through measurement and a good match is found between them. The intended antenna is a good candidature for working in GPS L2 band at 1.22 GHz, WLAN 5.2/5.8 GHz and WiMAX 5.5 GHz wireless applications.

Substrate‐integrated waveguide‐based slot antenna for 60 GHz wireless applications

AbstractThe substrate‐integrated waveguide (SIW)‐based slot antenna is proposed for millimeter wave applications that is 60 GHz applications. The proposed design uses a microstrip feed for excitation, the crown‐shaped slot is used, and dimensions are 14 mm × 8.4 mm × 0.381 mm. The genaralized parameters of the antenna are reported, those are voltage standing wave ratio (VSWR), reflection coefficient, farfield patterns, efficiencies, and surface current. It has impedance bandwidth of 3.64 GHz by proper alignment of slot that is crown, and resonant frequency is 60 GHz and also included antenna prototype. The reflection coefficient, VSWR of measurement results are reported, and the percentage of impedance bandwidth of simulation and measurement results is 6.06% and 6.02%.

Broad‐band H‐spaced head‐shaped slot with SIW‐based antenna for 60 GHz wireless communication applications

AbstractIn this article, a compact SIW‐based H‐spaced head‐shaped slot antenna is proposed, and slot is etched into the top, proposed design printed by RT‐Duriod 5880 substrate (εr = 2.2), which is accountable for achieving millimeter‐wave wireless applications, small size, and broadband operation. The SIW‐based slot antenna with a compacted dimension of 14 × 8 × 0.381 mm3 is fabricated and tested. The testing results show that the design proposed, having occupied frequency range from 58.5 to 61.72 GHz, respectively, covers V‐band (millimeter wireless communications applications). The testing and simulation result bandwidth range of a proposed design is 4.22 and 4.19 GHz. It has fine radiation characteristics for both E‐field and H‐field in all the preferred operational bands and generates superior performances compared to the existing design antenna in the reviews.

Polarization reconfigurable slot antenna for 5.8 GHz wireless applications

A CPW-fed circular polarization reconfigurable antenna is proposed in this paper. The antenna consists of two symmetrically placed inverted L-shaped slots. By using a T-type bias device to change the bias states of two PIN diodes which connect the two slots with the feed port respectively, right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) can be realized accordingly. For both states, the measured −10 dB impedance bandwidth is 5.78–5.96 GHz, while the measured 3 dB axial ratio bandwidth is 5.64–5.91 GHz (4.7%), both the bandwidths can cover the 5.8 GHz ISM band. By using floating ground and reflector board to enhance the front to back ratio of the antenna, 6.84 dBi measured gain can be realized at 5.8 GHz.

A 0.7 V, Ultra-Wideband Common Gate LNA with Feedback Body Bias Topology for Wireless Applications

An ultra-wideband (UWB) low noise amplifier (LNA) for 3.3–13.0 GHz wireless applications using 90 nm CMOS is proposed in this paper. The proposed LNA uses an improved common-gate (CG) topology utilizing feedback body biasing (FBB), which improves noise figure (NF) by a considerable amount. Parallel-series tuned LC network was used between the common-gate first stage and the cascoded common-source (CS) stage to achieve the maximum signal flow from CG to CS stage. Improved CS topology with a series inductor at the drain terminal in the second stage connected and cascoded CS third stage provides high power gain (S21) and bandwidth enhancement throughout the complete UWB. A common-drain buffer stage at the output provides high output reflection coefficient (S22). It achieves an average power gain (S21) of 14.7 ± 0.5 dB with a noise figure (NF) of 3.0–3.7 dB. It has an input reflection coefficient (S11) less than −11.7 dB for 3.3–13.0 GHz frequency and output reflection coefficient (S22) of less than −10.6 dB with a very high reversion isolation (S12) of less than −72.4 dB. It consumes only 5.2 mW from a 0.7 V power supply.

A 3.1–10.6 GHz UWB LNA Based on Self Cascode Technique for Improved Bandwidth and High Gain

In this work, we present a self cascode based ultra-wide band (UWB) low noise amplifier (LNA) with improved bandwidth and gain for 3.1–10.6 GHz wireless applications. The self cascode (SC) or split-length compensation technique is employed to improve the bandwidth and gain of the proposed LNA. The improvement in the bandwidth of SC based structure is around 1.22 GHz as compared to simple one. The significant enhancement in the characteristics of the introduced circuit is found without extra passive components. The SC based CS–CG structure in the proposed LNA uses the same DC current for operating first stage transistors. In the designed UWB LNA, a common source (CS) stage is used in the second stage to enhance the overall gain in the high frequency regime. With a standard 90 nm CMOS technology, the presented UWB LNA results in a gain $$\hbox {S}_{21}$$ of $$20.10 \pm 1.65\,\hbox {dB}$$ across the 3.1–10.6 GHz frequency range, and dissipating 11.52 mW power from a 1 V supply voltage. However, input reflection, $$\hbox {S}_{11}$$ , lies below $$-\,10$$ dB from 4.9–9.1 GHz frequency. Moreover, the output reflection ( $$\hbox {S}_{22}$$ ) and reverse isolation ( $$\hbox {S}_{12}$$ ), is below $$-\,10$$ and $$-\,48$$ dB, respectively for the ultra-wide band region. Apart from this, the minimum noise figure ( $$\hbox {NF}_{min}$$ ) value of the proposed UWB LNA exists in the range of 2.1–3 dB for 3.1–10.6 GHz frequency range with a a small variation of $$\pm \,0.45\,\hbox {dB}$$ in its $$\hbox {NF}_{min}$$ characteristics. Linearity of the designed LNA is analysed in terms of third order input intercept point (IIP3) whose value is $$-\,4.22$$ dBm, when a two tone signal is applied at 6 GHz with a spacing of 10 MHz. The other important benefits of the proposed circuit are its group-delay variation and gain variation of $$\pm \,115\,\hbox {ps}$$ and $$\pm \,1.65\,\hbox {dB}$$ , respectively.

Microstrip Hybrid Coupler with a Wide Stop-Band Using Symmetric Structure for Wireless Applications

In this paper, a wide stop-band microstrip coupler is presented . The proposed structure consists of coupled lines and step impedance cells, which are integrated to operate at 2.82 GHz for wireless applications. This coupler is formed by a symmetric structure so that the locations of the output ports relative to input are quiet similar. Accordingly, the magnitudes (also phases) of S 21 and S 31 overlap each other so that input signal can be selected through the output ports equally. There are little differences between the magnitudes and phases of S 21 and S 31 so that 0.97˚ phase shift is obtained. In comparison with previous works, the performance of the introduced coupler is improved. To get a better isolation, return loss and harmonic attenuation the frequency response is optimized without significant increase in circuit size. Moreover the first, second and third harmonics of S 21 and S 31 are well attenuated as well as a wide stop-band is obtained up to 15.1 GHz. The realized coupler is fabricated and measured. There is a good agreement between simulated and measured results, which confirms the design process.

Design of a novel compact microstrip diplexer with low insertion loss

AbstractIn this article, a microstrip diplexer is implemented based on a novel combination of the coupled lines and spiral structures in order to reduce the circuit size as well as insertion losses. This diplexer with an elliptic function frequency response operates at 2.4/2.79 GHz for wireless applications. Several transmission zeros on the both sides of two passbands are realized, which improve the selectivity. A theory method is presented that helps to miniaturization, control the resonance frequency, improve the insertion loss, and external quality factor simultaneously. The proposed diplexer has a compact size of 0.3λg × 0.25λg with low insertion losses of 0.18/0.39 dB at 2.4/2.79 GHz. The isolation between the two channels (S23) is better than 20.5 dB from DC up to 6 GHz. The designed diplexer is fabricated and measured. There is a good agreement between the simulated and measured results.

Design and development of triple band ACS fed antenna with M and rectangular shaped radiating branches for 2.45/5 GHz wireless applications

In this research, a low profile (12.5 × 18 mm2), easily tunable printed antenna consisting of λ/2 length M-shaped patch with rectangular and L-shaped strips (λ/2 length) that are fed by Asymmetric Coplanar Strip (ACS) is designed for WLAN and WIMAX applications. By varying the position of these λ/2 length simple structure radiating elements, three independent current paths can be produced which leads to generation of three independent resonant frequencies. The CST MWS simulated and VNA measured reflection coefficient (S11) results are compared and its analysis is presented along with its evolution stages, current distribution, smith chart, peak gain and radiation patterns properties. The −10 dB impedance operating bandwidths are about 140 MHz ranging from 2.41 to 2.55 GHz, 200 MHz from 3.45 to 3.65 GHz and 1700 MHz from 4.6 to 6.3 GHz respectively. Further, the developed structure can be easily integrated into advanced portable systems that support WLAN (2.4/5.2/5.8), 4.9 GHz US public safety and WIMAX (3.5/5.5) communication standards.

Design of a microstrip diplexer with a novel structure for WiMAX and wireless applications

In this paper, a novel combination of coupled lines, loops, step impedance and low impedance sections are used to design a compact microstrip diplexer. The designing method is based on obtaining transmission matrices and finding the effective parameters in tuning the resonance frequencies. T-shape tapped lines feed structures are added to three terminals of the proposed diplexer to decrease insertion losses at the both passbands without increasing the overall size. The proposed diplexer with a total size of 573.11mm2 operates at 2.6GHz for IEEE 802.16 and 802.20 WiMAX technology and 6GHz for wireless applications. The insertion losses at the lower and higher resonance frequencies are 0.6dB and 0.9dB, respectively. The proposed structure is simulated, fabricated and measured. The measurement results are in a good agreement with the simulations.

A Suspended Six-Port Transformer-Based Power Divider for 2.4 GHz Applications

This paper presents a transformer-based power divider with six-port suspending structure for 2.4 GHz wireless applications. The proposed power divider, which is featured with chip size (2.9 mm × 2.8 mm × 21 μm), was constructed by an 8-μm-thick Cu bottom electrode, a 5 μm-height supporting copper post, and an 8-μm-thick suspended spiral copper conducting layer with a 13 μm air gap. The main structure included two transformers and six input/output matching capacitors for simultaneously achieving two single-to-differential paths so that the chip size of the complex multiple-ports transceiver could be reduced. According to the results, the proposed divider has characteristics of the radio frequency (RF), and its input return losses are around −10 dB, output return losses are beneath −10 dB, and minimum amplitude imbalance is below 1.5 dB and less than 1° phase imbalance at 2.4 GHz operating frequency.

Design of a microstrip dual-frequency diplexer using microstrip cells analysis and coupled lines components

In this paper, a microstrip diplexer composed of two similar resonators is designed. The proposed resonator is consisting of four microstrip cells, which are connected to a coupled lines structure. In order to select a suitable geometric structure, first, all cells are assumed as undefined structures where there is a lack of basic information about their geometry and dimensions. Then, an equivalent LC circuit of the coupled lines is introduced and analyzed to estimate the general structure of the resonator respect to a requested resonance frequency. The proposed diplexer is designed to operate at 2.36 and 4 GHz for wireless applications. The insertion losses (S21 and S31) are decreased significantly at the resonance frequencies, so that they are 0.2 and 0.4 dB at 2.36 and 4 GHz, respectively. The designed diplexer is fabricated and measured and the measurement results are in a good agreement with the simulations.

Design and development of CPW fed monopole antenna at 2.45 GHz and 5.5 GHz for wireless applications

The behaviour of various families of the antenna structures is studied. In that, CPW (Coplanar Waveguide) fed antennas show better behaviour for the Wireless applications. The slot antenna is used for precise operating frequency, where the frequency spectrum is 2.45GHz and 5.5GHz. To achieve the proposed frequency, the slot antenna is fed with Coplanar waveguide is implemented and measured with dimensions of 70mm×70mm. To increase the bandwidth, first the mid section of two short slots of either side of the single pole length is increased slowly to check out the maximum bandwidth. The achieved peak bandwidth gradually starts decreasing at some length, considering the achieved peak value, The length responsible for decreasing peak value is to be noted. Now for obtaining the operating frequency lies in the frequency band, the mid section of long slot has to be decreased gradually; thus, operating frequency shows at 2.45GHz and 5.51GHz with return loss of −20dB, and the whole design is printed on the FR4 substrate for better efficiency to the proposed frequency at maximum bandwidth, and thereafter to check out the characteristics of antenna the parameters such as Return loss characteristics, VSWR, Azimuth pattern, Elevation pattern and 3D distribution pattern.