Showing papers on "Return loss published in 2019"

High-Isolation 3.5 GHz Eight-Antenna MIMO Array Using Balanced Open-Slot Antenna Element for 5G Smartphones

Abstract: A high-isolation eight-antenna multi-input multi-output (MIMO) array operating in the 3.5 GHz band (3.4–3.6 GHz) for future smartphones is proposed. Here, a novel balanced open-slot antenna is designed as an array antenna element, in which this antenna design can yield a balanced slot mode (with reduced ground effects) that can enhance the isolation between two adjacent input ports. Furthermore, by meticulously arranging the positions of the eight antenna elements, desirable polarization diversity can also be successfully achieved, which further mitigates the coupling between antenna elements. A prototype was manufactured to validate the simulation. A good impedance matching (return loss > 10 dB), high isolation (>17.5 dB), high total efficiency (>62%), and low envelope correlation coefficient (ECC, <0.05) were measured across the desired operation bandwidth. To verify the MIMO performance, ergodic channel capacity using the Kronecker channel model was calculated. The effects of hand phantom were also studied.

Dual-Band Eight-Antenna Array Design for MIMO Applications in 5G Mobile Terminals

Abstract: This paper proposes a dual-band eight-antenna array for multiple-input and multiple-output (MIMO) applications in 5G mobile terminals. The designed MIMO antenna array comprises eight L-shaped slot antennas based on stepped impedance resonators (SIRs). The required dual-resonance can be obtained by adjusting the impedance ratio of the SIR, and good impedance matching can be ensured for each antenna element by tuning the position of the microstrip feed line. The experimental results show that a measured return loss of higher than 10 dB and a measured inter-element isolation of greater than 11.2 dB have been obtained for each antenna element with a simulated total efficiency of larger than 51% across the long term evolution (LTE) band 42 (3400-3600 MHz) and LTE band 46 (5150-5925 MHz). In addition, the measured envelope correlation coefficient (ECC) is lower than 0.1 between arbitrary two antenna elements, and the proposed MIMO antenna array realizes a simulated channel capacity of higher than 36.9 bps/Hz within both operation bands. Furthermore, the MIMO antenna array can maintain acceptable radiation and MIMO performance in the presence of specific anthropomorphic mannequin (SAM) head and human hands.

Eight Element Multiple-Input Multiple-Output (MIMO) Antenna for 5G Mobile Applications

Abstract: This work presents a systematic design of high performance eight element antenna array for a 5G mobile terminal operating at 2.6/3.5 GHz bands. The proposed eight element slot antenna array based on unit monopole slot antenna embedded in the metal casing or ground resonates at fundamental mode at 2.6 GHz. The antenna array is developed from four antennas (open-end slot antenna) etched near to the corner edges of the printed circuited board with supported pairs of vertically mounted slot antennas in middle section of the long edge ground plane. This combination of the antenna elements provided pattern diversity and enabled the smartphone in the reception of the signal in a different direction. The impedance bandwidth based on -10 dB return loss criteria cover from 2.4 GHz to 3.6 GHz includes the two allocated bands of (2400 MHz to 2600 MHz) and (3400 MHz to 3600 MHz) for 5G cellular communication systems. The vital MIMO performance measures as envelope correlation coefficient or ECC is less than 0.2 for any two antenna array meeting the required standard of less than 0.5 alongside the mean effective gain or MEG ratio of any two antenna meeting the required standard of less than 3 dB for power balance and optimal diversity performance. As modern smartphone demand desires slim handsets, the after mentioned compact multiple antenna structure can be easily implemented for the future smartphones as it utilizes the conductive sheet or chassis and the middle vertically mounted antenna do not use the additional space of the chassis or ground. The customer hand or human hand effect on the multiple antenna array to mimic the use of mobile phone customer is also studied. The maximum MIMO Channel capacity based on measured result is 34.25bps/Hz and is about 3 times of 2 × 2 MIMO operations.

Quasi-Yagi Antenna Array With Modified Folded Dipole Driver for mmWave 5G Cellular Devices

Abstract: A novel quasi-Yagi antenna is proposed for millimeter-wave (mmWave) 5G cellular handsets operating in the 28 GHz band. The proposed antenna is designed to be compact through modification of the planar folded dipole topology so that it can be mounted inside a compact mobile terminal. A vertically stacked structure utilizing a multilayer printed circuit board (PCB) and via holes is applied to the antenna topology to minimize the antenna lateral width while maintaining the characteristics of the planar folded dipole antenna. A single antenna yields a $-$ 10 dB bandwidth for a return loss of 12.3% (26.3 to 29.75 GHz) and a gain of 5.51 dBi at 28 GHz. The change in beam patterns due to the chassis effect when four-element linear arrays are inserted into the upper and side edge inside the terminal is analyzed.

Compact Integrated Full-Duplex Gap Waveguide-Based Radio Front End For Multi-Gbit/s Point-to-Point Backhaul Links at E-Band

Abstract: This paper presents the design and realization of a high data rate radio front-end module for point-to-point backhaul links at E-band. The design module consists of four vertically stacked unconnected metal layers without any galvanic and electrical contact requirements among the building blocks, by using gap waveguide technology. The module components are a high-gain array antenna, diplexer, and circuitry consisting of a transmitter (Tx) and a receiver (Rx) monolithic microwave integrated circuits (MMICs) on a carrier board, which is successfully integrated into one package with a novel architecture and a compact form. The diplexer consists of two direct-coupled cavity bandpass filters with channels at 71–76 GHz and 81–86 GHz with a measured return loss of 15 dB and an isolation greater than 50 dB. A wideband $16\times 16$ slot array antenna with a measured gain of more than 31 dBi is used to provide high directivity. The measured results show that the packaged transmitter provides a conversion gain of 22 and 20 dB at 76 and 86 GHz, respectively, with an output power of 14 and 16 dBm at 1-dB gain compression point, at the same frequencies. The packaged receiver shows an average conversion gain of 20 dB at 71–76-GHz and 24 dB at 81–86-GHz bands. A real-time wireless data transmission is successfully demonstrated with a data rate of 8 Gbit/s using 32-quadrature amplitude modulated signal over 1.8-GHz channel bandwidth with spectral efficiency of 4.44 bit/s/Hz. The proposed radio front end provides the advantages of low loss, high efficiency, compact integration, and a simple mechanical assembly, which makes it a suitable solution for small-cell backhaul links.

Dual-Band Dual-Sense Polarization Reconfigurable Circularly Polarized Antenna

Abstract: This letter presents a novel dual-band circularly polarized slot antenna. The far-field polarization of the antenna can be switched electronically between left-hand circular polarization and right-hand circular polarization. A 50 Ω microstrip feed line is divided into four arms those excite a ground plane slot. The p-i-n diodes are introduced in the arms for polarization switching. A prototype dual-band dual-sense antenna with f 01 = 2.4 GHz and f 02 = 5.2 GHz is fabricated using a 1.6 mm thick FR4 substrate. The measured 3 dB axial ratio bandwidths are more than 16.6% and 5.7% at the lower and upper bands, respectively. The measured return loss is more than 10 dB over the wireless local area network (LAN) bands.

Novel approach for the design and analysis of a terahertz microstrip patch antenna based on photonic crystals

Abstract: In this study, we designed and analyzed five terahertz microstrip patch antennae based on a modified photonic band gap substrate in the frequency range from 0.5 to 0.8 THz. The objective was to achieve the best antenna characteristics around 0.65 THz, which has applications in sensing and communication technologies. Simulations were performed for rectangular patch antennae based on different substrates, including homogeneous, periodic photonic crystals and four new aperiodic photonic crystal substrates. Each of the modified photonic crystal substrates contained several sets of air holes perforated in the polyimide substrate, where each set had its own specific radius. The proposed antennae had high radiation characteristics around 0.65 THz compared with conventional antenna. The best characteristics were achieved with the second antenna structure, which obtained a minimal return loss of −83.73 dB and a wide bandwidth greater than 230 GHz. The gain achieved and radiation efficiency were 9.19 dB and 90.84%, respectively. The simulations were performed based on the finite integration technique with the commercially available CST Microwave Studio simulator.

A Bidirectional Same Sense Circularly Polarized Endfire Antenna Array With Polarization Reconfigurability

Abstract: In this communication, a bidirectional same sense circularly polarized (Bi-SSCP) endfire antenna array with reconfigurable polarization is proposed and implemented. First, a circular polarization (CP) reconfigurable endfire antenna element is realized by adopting two pairs of switchable electric dipoles, which have a 180° phase difference inherently. Along with the fixed magnetic dipole, the endfire antenna element can work at two CP states, i.e., left-hand CP (LHCP) and right-hand CP (RHCP) by switching the states of the two electric dipoles. Then, a Bi-SSCP endfire antenna array with polarization diversity is developed by using two identical endfire antenna elements placed back-to-back with a single feeding probe. For verification, prototypes of the designed endfire antenna element and Bi-SSCP endfire antenna array are fabricated and measured. The measured results show reasonable agreement with the simulated ones. The measured overlapped bandwidth for 10 dB return loss and 3 dB axial ratio of the Bi-SSCP endfire antenna array is from 5.7 to 5.9 GHz for the two CP states.

Substrate Integrated Plasmonic Waveguide for Microwave Bandpass Filter Applications

Abstract: In this paper, we numerically and experimentally demonstrate a substrate integrated plasmonic waveguide (SIPW) concept and its application in microwave bandpass filters. This SIPW consists of double arrays of slots etched on the top and bottom metal layers of a substrate integrated waveguide (SIW) to support spoof surface plasmon polariton (SSPP) modes with low and high cutoff frequencies. The simulated results show that by tuning the parameters of the SIPW's unit cell, the dispersion characteristics can be engineered at will. Then, we propose a sharp roll-off microwave bandpass filter based on this SIPW. This filter has a passband from 7.5 to 13.0 GHz with high return loss and low insertion loss. Furthermore, to demonstrate the independent tuning of the passband of the filter, we also design two microwave bandpass filters with passbands of 9.2-13.0 GHz and 7.5-10.5 GHz by decreasing the distance between two rows of via holes and increasing the slot length, respectively. Finally, to experimentally validate the filter designs, we fabricate and measure three prototypes and find that the experimental results are in excellent agreement with the simulations. This SIPW concept may have extensive potential applications in the development of various plasmonic integrated functional devices and circuits.

Analysis and design of a terahertz microstrip antenna based on a synthesized photonic bandgap substrate using BPSO

Abstract: A microstrip patch antenna based on a synthesized photonic bandgap (PBG) substrate is designed and analyzed by using a technique based on the combination of an evolutionary heuristic optimization algorithm with the CST Microwave Studio simulator, which is based on the finite integral technique. The initial antenna is designed by analyzing air cylinders embedded in a thick silicon substrate, which has high relative permittivity. Then, to synthesize the PBG substrate, a binary particle swarm optimization (BPSO) algorithm is implemented in MATLAB to design a two-dimensional (2D) photonic crystal on a square lattice that improves the initially designed microstrip antenna. The unit cell is divided equally into many square pixels, each of which is filled with one of two dielectric materials, silicon or air, corresponding to a binary word consisting of the binary digits 0 and 1. Finally, the performance of the initial antenna is compared with the BPSO-optimized antenna using different merit functions. The results show remarkable improvements in terms of the return loss and fractional bandwidth. Both microstrip patch antennas based on the synthesized photonic crystal substrate achieve noticeable sidelobe suppression. Furthermore, the first design, which is a dual-band antenna, shows a return loss improvement of 5.39 %, while the fractional bandwidth of the second design is increased by 128 % (bandwidth of 128 GHz), compared with the initial antenna based on the air-hole PBG substrate. Both antennas maintain a gain close to 9.17 dB. Also, the results show that the obtained antennas have resonant frequencies around 0.65 THz, as required for next-generation wireless communication technology and other interesting applications.

Investigation on Metamaterial Antenna for Terahertz Applications

Abstract: In this paper, the metamaterial based rectangular microstrip patch antenna is proposed and designed for THz applications. The proposed antenna is designed with the help of circular split ring resonator as unit cell which is considered as metamaterial. By incorporating metamaterial in the conventional microstrip patch antenna, the size is reduced and the performance of antenna is improved. The proposed antenna has the dimensions of 180 × 212 ×10 µm 3 which is designed on Quartz substrate which is fed by microstrip line feed technique. Additionally, the performance of the metamaterial antenna is analyzed by varying unit cell gap size and thickness. The antenna resonates at 1.02 THz which gives the return loss of -65 dB. Thus, the proposed antenna can be utilized in THz region.

Design and Analysis of a Slotted Microstrip Antenna for 5G Communication Networks at 28 GHz

Abstract: The next generation of mobile communication system is the fifth generation (5G) communication systems that used mm-wave bands to achieve high data rates and increase the user capacity. 5G communication system require a low profile, lightweight, high gain and simple structure antennas to ensure reliability, mobility, and high efficiency. Due to the low atmospheric absorption rate of electromagnetic waves at 28GHz, this paper aims to design a directional single element slotted microstrip antenna with compact size to operate at 28GHz for 5G applications. The proposed antenna is simulated by using High Frequency Structure Simulator (HFSS) software on FR4 substrate with 4.4 dielectric constant, 0.8 mm thickness, and 0.02 loss tangent. In order to achieve the requirements of the proposed antenna, the patch is modified by loading specific slots; and the performance of the antenna is studied in terms of antenna parameters that are return loss, VSWR, gain, and radiation pattern, and compared with published results.

Coplanar Waveguide Antenna with Defected Ground Structure for 5G Millimeter Wave Communications

Abstract: This paper introduces a novel compact antenna for the millimetre-wave (MMW) frequency range, having some ultra-wideband capability. The proposed antenna has been designed to target the 5th generation operating bands ranging from 24GHz to 70GHz and can be considered as a potential candidate for 5G wireless networks. The designed antenna uses a microstrip patch structure, fed by coplanar waveguide (CPW); it shows excellent return loss performance in the 36 GHz band that is expected to be deployed for 5G mobile in the relatively near future, but it also has adequate return loss from 30 to 50 GHz and a potentially acceptable figure at the important 60 GHz oxygen-absorption band, which may be deployed later under 5G or the forthcoming sixth generation. The design is etched on high performance planar substrate, using a coplanar waveguide structure on the upper surface, but with a defected ground plane underneath.

Patch antenna with improved performance using DGS for 28GHz applications

Abstract: A compact size patch antenna resonating at 28GHz is presented in this paper. The antenna is simple in structure and fed using microstrip line which enhances its use with different circuitry. The antenna is designed keeping in mind the specification proposed by European Standard Telecommunications series (ETSI). Proposed antenna shows good results in term of return loss and gain, the antenna also satisfies the Federal communication commission (FCC) proposed bandwidth for 28GHZ i.e. 27.5-28.25GHz. ROGERS RT/Duroid 6002 is used as a substrate of the antenna, while the antenna is simulated using commercially available software Higher Frequency Structural Simulator (HFSS).

Miniaturized DC–60 GHz RF PCM GeTe-Based Monolithically Integrated Redundancy Switch Matrix Using T-Type Switching Unit Cells

Abstract: This article presents an approach to monolithically implement radio-frequency (RF) phase change material (PCM) germanium telluride (GeTe) T-type switch as a switching unit cell for millimeter-wave (mmWave) redundancy switch matrix applications. The miniature T-type switch demonstrates three states of operation, including one crossover state and two turn states. A seven-layer microfabrication process, including an additional conductive layer to reduce the $RC$ time constant due to the bias network routing, is developed and optimized to fabricate the multiport RF devices. A $4 \times 6$ PCM-based redundancy switch matrix is developed by monolithically integrating four T-type switches in the cascade configuration. Thermal crosstalk in PCM switches is experimentally investigated using submicrometer spatial resolution transient thermal imaging. The presented T-type switch has the device periphery of 0.55 mm $\times \,\,0.55$ mm, while the overall integrated PCM redundancy switch matrix is fabricated with a device footprint of 0.88 mm $\times \,\,1.1$ mm. The measured results of the T-type switches demonstrate an excellent RF performance with lower than 1.6 dB insertion loss, better than 20 dB return loss, and higher than 20 dB isolation in all states from dc–67 GHz. The redundancy switch matrix exhibits an insertion loss less than 3 dB, return loss better than 14 dB, and isolation higher than 20 dB from dc–60 GHz. To the best of our knowledge, this is the first implementation of a PCM-based redundancy switch matrix.

228-Spatial-Channel Bi-Directional Data Communication System Enabled by 39-Core 3-Mode Fiber

Abstract: We demonstrated simultaneous usage of 228 spatial channels (effectively) within a strand of fiber. We fabricated a 13-km 39-core 3-mode fiber and constructed a bi-directional space division multiplexing (SDM) transmission setup by using cascaded spatial multiplexers on both fiber ends. Aggregated intercore crosstalk and return loss of the system were below -35 and above 31 dB, respectively, over the C and L bands. The feasibility of using bi-directional SDM transmission was investigated using 10 GBaud, 37.38-Gb/s dual-polarization QPSK signals at 1550 nm and coherent detection with a 6 × 6 multi-input-multi-output equalizer. Excellent transmission properties were obtained for most spatial channels.

Dynamically Tunable Attenuator on a Graphene-Based Microstrip Line

Abstract: In this paper, a novel type of dynamically tunable attenuator based on graphene is proposed. This type of attenuator is composed of one or two graphene sandwich structures (GSSs) and a microstrip line. The GSSs are spread on the substrate of microstrip line near the signal strip along the direction of propagation to dissipate electromagnetic field. By the application of biased voltage, the surface impedance of graphene can be tuned, and consequently, the insertion loss of microstrip line can also be adjusted while the return loss maintains relatively low level. A transverse equivalent network and a closed form of attenuation of each attenuator are also proposed, which can be utilized to analyze the performance of attenuator with different critical parameters of graphene in detail. According to the analysis, there is a maximum value of the attenuation as the surface impedance of graphene rises from 0 to $3000~\Omega /\Box $ . As an example, a prototype of each tunable microstrip line attenuator operating at gigahertz frequencies is fabricated and measured. The fabricated attenuator present favorable attenuation ranges from 3 to 15 dB, at the operating frequency from 9 to 40 GHz, and with a stable wideband attenuation corresponding to bias voltage changing from 0 to 4.0 V.

Conceptual design of a compact four-element UWB MIMO slot antenna array

Abstract: In this study, an effective methodology to design a compact four-element multiple-input-multiple-output (MIMO) antenna with high performance over ultra-wide bandwidth (BW) is presented and discussed. Taking the advantages of symmetry of most planar ultra-wideband (UWB) antennas, an asymmetric feeding scheme technique is utilised to chop a previously developed UWB slot antenna with overall dimensions of 30 mm × 30 mm into two halves to yield a more compact structure while retaining its overall frequency- and time-domain performances. Benefiting from orthogonal orientation, a compact UWB MIMO antenna system is arranged using four half-sized elements. The proposed MIMO antenna has an overall size of 40 mm × 40 mm and exhibits impedance BW from 2.94 to more than 14 GHz (10 dB return loss) with port isolation better than 17 dB over the entire operating band without using any decoupling structures. This is achieved via the inherent directional radiation properties of slot antenna elements and their asymmetrical placements. Envelope correlation coefficient is computed, and it is within the acceptable limit, which validates the design concept for building a compact MIMO antenna system with good performance.

Design, analysis and fabrication of compact dual band uniplanar meandered ACS fed antenna for 2.5/5 GHz applications

Abstract: In this research, a compact meandered shape design of printed antenna with dual operating frequencies for 2.5/5 GHz applications is presented and experimentally investigated. The proposed multi band antenna is feed with asymmetric coplanar strip (ACS) and has a size of 10 mm × 19 mm. The L and meandered elements acts as a radiating elements that produces operating frequencies from 2.5 to 2.7 GHz and from 4.6 to 6.1 GHz with 200 and 1500 MHz impedance bandwidths respectively. Also, simulation study of feeding the proposed structure with microstrip concept is carried out and similar performance results are found in both ACS and microstrip techniques. The performance of the dual band antenna in terms of return loss, design evolution, radiation patterns and peak gain is studied.

Wideband Loop Antenna With Split-Ring Resonators for Wireless Medical Telemetry

Abstract: This letter presents a wideband flexible loop antenna with split-ring resonators (SRRs) for use in wireless medical telemetry. This design covers the entire MedRadio band (401–406 MHz) and four Industrial, Scientific, and Medical (ISM) bands (433.1–434.8, 868.0–868.8, and 902.8–928.0 MHz and 2.4–2.48 GHz). The SRRs improve the loop antenna return loss and reduce the power absorbed inside the human body over the multiband frequency ranges; they also result in increased radiation efficiency, gain, and transmission coefficient. A human body model has been used to study and optimize the antenna performance in a realistic environment and shows a reduction in specific absorption rate when the SRRs are used. Measurements are conducted in a tissue-simulating liquid phantom and show a good agreement with the simulations. This novel antenna could be used for a range of implantable applications such as wireless data transmission and wireless power transfer.

Four-Way Filtering Power Divider Using SIW and Eighth-Mode SIW Cavities With Ultrawide Out-of-Band Rejection

Abstract: 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.

Microstrip patch antenna with defected ground structure for biomedical application

Abstract: Proper narrowband antenna design for wearable devices in the biomedical application is a significant field of research interest. In this work, defected ground structure-based microstrip patch antenna has been proposed that can work for narrowband applications. The proposed antenna works exactly for a single channel of ISM band. The resonant frequency of the antenna is 2.45 GHz with a return loss of around -30 dB. The -10dB impedance bandwidth of the antenna is 20 MHz (2.442-2.462 GHz), which is the bandwidth of channel 9 in ISM band. The antenna has achieved a high gain of 7.04 dBi with an increase of 17.63% antenna efficiency in terms of realized gain by using defected ground structure. Three linear vector arrays of arrangement 1 2, 1 4 and 1 8 have been designed to validate the proposed antenna performances as an array. The proposed antenna is light weighted, low cost, easy to fabricate and with better performances that makes it suitable for biomedical WLAN applications.

Multimode waveguide crossing based on a square Maxwell's fisheye lens.

Abstract: Mode-division multiplexing (MDM) is an emerging large-capacity data communication technology utilizing orthogonal guiding modes as independent data streams. One of the challenges of multimode waveguide routing in MDM systems is decreasing the mode leakage of waveguide crossings. In this article, a square Maxwell's fish-eye lens as a waveguide crossing medium based on quasiconformal transformation optics is designed and implemented on a silicon-on-insulator platform. Two approaches were taken to realize the designed lens: graded photonic crystal and varying the thickness of the silicon slab waveguide. Three-dimensional numerical simulations show that the designed multimode waveguide crossing has an ultrawide bandwidth from 1260 to 1675 nm with a compact footprint of only 3.77×3.77 μm2. For the first three transverse electric modes (TE0, TE1, and TE2), the designed waveguide crossing exhibits an average insertion loss of 0.24, 0.55, and 0.45 dB; a crosstalk of less than -72, -61, and -27 dB; and a maximum return loss of 54, 53, and 30 dB, respectively. The designed waveguide crossing supports low-distortion pulse transmission with a high fidelity factor of 0.9857. Furthermore, the proposed method can be expanded to design waveguide crossings with an even higher number of supporting modes by increasing the size of the lens.

Geometric Analysis and Systematic Design of a Reflective-Type Phase Shifter With Full 360° Phase Shift Range and Minimal Loss Variation

Abstract: In this article, a geometric method, along with the concept of the reference circle, is proposed for the analysis of reflective-type phase shifter (RTPS). Comprehensive analyses of popular reflective loads, including capacitive load (CL), resonated load (RL), and $\pi $ -type load, are presented, revealing their limitations. The triple-resonating load technique is proposed to accomplish a full 360° phase shift range and suppress the loss variation. Further, a systematic design methodology for the RTPS using triple-resonating load is developed. Fabricated in 65-nm CMOS technology, the proposed RTPS occupies a core chip area of $0.076~\mu \text{m}^{2}$ . It achieves the first-ever 379° phase shift range at 29 GHz with only one control voltage. With dual-voltage control, a full 360° phase shift range with 8.3 ± 0.2 dB insertion loss is achieved. For both control methods, the return loss is better than 22.8 dB for all phase shift states.

Hybrid Fractal Antenna Using Meander and Minkowski Curves for Wireless Applications

Abstract: This paper describes a novel design of Minkowski and Meander curves based hybrid fractal antenna for mobile devices used for communication in delay tolerant networks, wireless sensor networks and mobile adhoc networks. Meander curve improves the impedance bandwidth. Minkowski fractal curve gives its contribution to make antenna multiband. The proposed antenna resonates at five frequencies 1.98, 5.94, 10.61, 12.73, 14.85 GHz. Prior to fabrication, better performance parameters such as return loss, radiation pattern, gain, current distribution, impedance, VSWR are achieved. The maximum bandwidth 2.83 GHz and gain 9.0 dB at 2.4 GHz are achieved. The proposed antenna can be used for various applications like Bluetooth, Wi-Fi, Wi-Max, Wi-Bro, AWS, GPS, S-DMB, WLAN 802.11b/g and DTH services etc. Simulated and measured results are compared and are found in agreement with each other.

Analysis and Design of Microstrip Patch Antenna for Radar Communication

Abstract: In modern days, Microstrip patch antennas become more popular because of its fascinating features such as low cost, light weight, low profile planar configuration which can be effortlessly made conformal to host surface. In order to overcome the demerits of patch antenna like low gain, low efficiency, low directivity and narrow bandwidth, it is obligatory to implement patch antennas in array configuration by creating cuts in the ground, by increasing the height of patch, rising the substrate thickness and by decreasing the permittivity of the substrate. Percentage of bandwidth of the patch antenna can also be increased by the above mentioned techniques. Circuit board FR4 (Flame Retardant 4) is used for designing this patch antenna, since it has fabulous performance during the fabrication process. In this paper, design of two layered electromagnetically coupled rectangular patch antenna with microstrip-line inset-fed with minimized return loss has been proposed for the wireless devices.

Moore, Minkowski and Koch Curves Based Hybrid Fractal Antenna for Multiband Applications

Abstract: Today’s world, multiband antenna has immensely beneficial for fulfill the requirements of wireless communication. In this paper, Hybrid Fractal Antenna (HFA) is designed using three popular fractal curves koch, minkowski and moore. The generator curve is created by adding minkowski curve and invert of koch curve. This hybrid generator curve is then superimposed on moore curve to get proposed HFA. FR4 material is used for the design of proposed HFA. The effect of defected ground and dielectric constant of different materials on the performance of antenna is studied. Proposed antenna is fabricated and S11 in dB is measured using Vector Network Analyzer. A comparison between simulated and measured return loss is done. It is found that simulated and measured results are agreement with each other. The antenna parameters such as return loss, VSWR, radiation pattern, gain are described in this article. A gain of 20.1 dB is obtained at frequency 1.70 GHz. The maximum bandwidth of proposed HFA is 2870 MHz and VSWR range varies between 1.887MAX and 1.008MIN. The dimensions of proposed HFA is 41.5 × 37 mm2 which is small as compared to existing hybrid geometries in literature. This proposed HFA can be used for Bluetooth (2.4 GHz), Wi-Fi (IEEE 802.11b and 802.11g) Wireless LAN (5.5 GHz), Wireless computer networking (2.4 GHz and 5.5 GHz), Wi-MAX (5.20 GHz–5.8 GHz), Satellite communication uplink (5.90 GHz), Military satellite downlink (7.25–7.30 GHz) applications.

Compact Wideband Reflective/Absorptive Bandstop Filter With Multitransmission Zeros

Abstract: Novel wideband reflective bandstop filters (RBSFs) and absorptive bandstop filters (ABSFs) with high stopband rejection (SR) and good frequency selectivity are proposed. Based on a coupled line (CL) with an open-circuited stub, a broad stopband response with three transmission zeros (TZs) is implemented in a compact circuit configuration. Two modified CL structures are loaded at the ports resulting in two additional TZs. In addition, a grounded resistor is introduced to absorb unwanted signals in the stopband. For demonstration, the five-zero RBSFs and three-zero ABSFs operating at 2 GHz are designed and built. The reflective filter shows a 35-dB SR with 79.5% relative bandwidth (RB). The absorptive filter with 69.5% RB of 24-dB SR achieves an all-passband 12.2-dB return loss. Good agreements between simulated and measured results are observed.

CPW-fed ultra-wideband slot antenna with broadband dual circular polarization

Abstract: A novel coplanar waveguide (CPW) fed ultra-wideband slot antenna with broadband dual circular polarization is proposed, fabricated and measured. The antenna structure is simple and consists of two CPW-fed ports to achieve both right-hand circular polarization and left-hand circular polarization at the same frequency band with the overall size of 48 × 48 × 1 mm3. The design process of the proposed antenna is given and the circular polarization mechanism is analyzed from the surface current distribution. The variation of return loss, port isolation and axial ratio (AR) with antenna parameters is simulated. By optimizing the radiation patch and improving the ground plane, the ultra wide impedance bandwidth and broad axial ratio bandwidth are achieved. The measured impedance bandwidth is 153.1% (1.9–14.3 GHz) with return loss better than 10 dB, and the measured 3 dB axial ratio bandwidth is 102.6% (1.9–5.9 GHz). The gain and port isolation are better than 3 dB and 15 dB, respectively, within the AR band.