Authors:
Donghee Park;Longyue Qu;Hyeongdong Kim;
Pages: 1509 - 1514 Abstract: This research proposes a single-fed circularly polarised (CP) antenna operating at 2.4 GHz for wireless local area network applications by utilising ground radiation, which is particularly applicable to small-size printed circuit boards (PCBs) such as the Internet of Things (IoT) devices. To simultaneously excite two orthogonal degenerate ground modes for CP wave radiation, ground mode tuning (GMT) technique is further adopted to adjust the resonant frequencies of the two ground modes. The proposed small antenna element is located at an optimum position of the PCB based on the analysis of the theory of characteristic modes for simultaneously exciting two ground characteristic modes. Experiments verify good performances with the compact size of 0.28 λ0 × 0.28 λ0 × 0.008 λ0 (including the ground plane and antenna element) at 2.45 GHz. The proposed antenna achieves 3 dB axial ratio bandwidth of 10.6% (2.36-2.62 GHz) and -6 dB impedance bandwidth of 7.4% (2.34-2.52 GHz). The measured efficiency of the proposed antenna is 55.3%, and the direction of the maximum radiation for LHCP and RHCP is + z and - z, respectively. The measured gain is 1 dBi at 2.45 GHz. The proposed antenna applies to small-size PCBs for CP communication, which is desirable for practical wireless products. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Qing Liu;Dong-Fang Zhou;De-Wei Zhang;
Pages: 1515 - 1521 Abstract: A new class of compact microstrip bandpass filters in doublet topology based on a dual-mode loop microstrip resonator with controllable locations of input/output feeding lines is presented and researched. Filters with up to five poles are proposed and researched. Diagonal cross-coupling path in box-like topology can be introduced to produce a finite transmission zero (TZ) with controllable position. Some design examples are provided to illustrate the performances of the proposed two-, three-, four- and five-pole filters with controllable TZs. A three-pole and a five-pole filters were fabricated and measured. Good agreement is achieved between the simulated and the measured results. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
S.H. Ramazannia Tuloti;P. Rezaei;F. Tavakkol Hamedani;
Pages: 1522 - 1528 Abstract: Having studied the transmitarray antennas, it is found that the cells depending on their location on the antenna aperture should have a specific slope in the transmission phase diagram in terms of frequency. The central cell has the most negative slope, and as long as the centre is farther away, the negative slope of the transmission phase diagram in terms of frequency is reduced. Therefore, the ability to change the slope of the transmission phase diagram in terms of frequency in the unit cell is essential. To validate the proposed approach, by providing a suitable unit cell, a typical X-band antenna with an aperture size of 20.55λ02 at 10 GHz has been designed, fabricated, and tested. In order to evaluate the effect of the transmit array aperture, the gain enhancement value of the antenna is calculated and maximum gain of 5.9 dBi at 10.5 GHz and a 29.71% 1 dB gain bandwidth is achieved. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Jin-Wei Pan;Kai Fu;Qi Liu;Wen-Sheng Zhao;Linxi Dong;Gaofeng Wang;
Pages: 1529 - 1535 Abstract: The crosstalk effects of differential through silicon vias (D-TSVs) are studied. The equivalent circuit model is developed, with the circuit elements extracted analytically. Using the three-dimensional (3D) full-wave field solver HFSS, the circuit model is validated up to 100 GHz. By virtue of the circuit model, the noise couplings in the D-TSVs are evaluated. It is found that the noise coupling can be cancelled in the D-TSVs for a particular case. Finally, the influence of floating silicon substrate on the crosstalk in the D-TSVs is investigated. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Mahsa Valizdeh;Hoda Ameri;Reza Faraji-Dana;
Pages: 1536 - 1545 Abstract: Here, a simple, accurate and rapidly convergent method based on complex images (CI) technique is developed to derive a closed-form Green's function for periodic structures perpendicular to a substrate. The Green's function is represented in a two criteria form, based on the distance of the field point from the source point. That is, for the small field point to source point distances, it is given in terms of a CI representation, while for the larger field point to source point distances, the contribution of the poles in the spectral domain function is used through the application of the residue theorem. The main advantage of the derived Green's function lies on its accuracy, ease of computation, and fast convergence. The usage of the derived closed-form Green's functions in the mixed potential integral equation (MPIE), an efficient method for analysing periodic structures, has been introduced. The proposed method is applied to several examples, and the results are in good agreement with the simulations in commercial software. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Koray Surmeli;Ahmet Kizilay;
Pages: 1546 - 1553 Abstract: In this study, a slant polariser design for directional antennas and antenna arrays is proposed. The polariser changes linear polarisation (vertical or horizontal polarisation) to slant (45°) polarisation of a directional antenna and arrays. The polariser consists of five layers that are formed by metallic strips with different angular orientations on each layer. In this way wide impedance and pattern bandwidth is obtained. Theoretical background of the polariser is examined and calculated parameters for the polariser are given. The designed slant polariser is placed in front of the horn antennas and the stacked patch antenna array. The polariser has a wide bandwidth and operates in the frequency range of 6.5-18 GHz. The performance of these polarisers are examined with simulations and verified by experimental results. Measured radiation pattern results show that the polariser successfully changes the polarisation for directional antennas and antenna array. Also, measurement results show that by using the polariser these directional antennas and antenna arrays can radiate in both two linear polarisation components (both vertical and horizontal polarisation). PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Eliseo García;Carlos Delgado;Lorena Lozano;Felipe Cátedra;
Pages: 1554 - 1563 Abstract: The multilevel fast multipole algorithm is a popular technique that enables the efficient solution of the method of moments (MoM) matrix equations. In this work, the authors address the adaptation of this method to the compute unified device architecture (CUDA), a relatively new computing infrastructure provided by NVIDIA, and the authors take into account some of the limitations that appear when the geometry under analysis becomes too large to fit into the memory of graphics processing units. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Anumoy Ghosh;Gobinda Sen;Mukesh Kumar;Santanu Das;
Pages: 1564 - 1571 Abstract: A microstrip line fed planar monopole patch antenna is designed to provide impedance bandwidth ( S11 ≤ -10 dB) of 2.56-12.25 GHz, thus exhibiting ultra-wideband (UWB) characteristic. Two metallic strips are branched symmetrically from the patch radiator to generate resonant frequencies at 0.9 and 1.9 GHz, corresponding to GSM operating frequencies. A filtering element based on electromagnetic bandgap (EBG) unit cell is placed near the feedline of the antenna to introduce two notches at 5.17 and 7.97 GHz thereby mitigating any interference from lower WLAN and X-band satellite uplink frequencies respectively. The proposed structure has satisfactory gain at the GSM frequencies and fairly constant gain with a variation of PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Reza Toreinia;Morteza Kazerooni;Mohsen Fallah;
Pages: 1572 - 1579 Abstract: This article introduces a new type of soft surface as truncated soft surface (TSS) for the mutual coupling reduction in stacked aperture-coupled microstrip patch phased array antennas. Also, a meandered TSS (MTSS) is introduced with a reduced size compared to the TSS. Conventional soft surfaces not only prevent the propagation of waves in the soft longitudinal direction but also guide the waves in the transversal direction. So, the mutual coupling decreases in the soft longitudinal direction and increases in the transversal direction. Truncation in the transversal direction prevents the waves from guidance on TSSs. Simulation results show that using this technique helps to decrease the mutual coupling in the E-plane of a phased array antenna without any noticeable increase in the H-plane coupling. Also, there is no blind spot in the desired scan range and the embedded element pattern will not have any null in the scan range. Using this technique, the acceptable scan range for an antenna substrate with a low relative permittivity of 2.33, can be increased up to 45°. Finally, measurement results show that using TSS leads to an 8-dB decrement in the E-plane mutual coupling. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Neng-Wu Liu;Xin-Peng Chen;Lei Zhu;Xi Chen;Guang Fu;Ying Liu;
Pages: 1580 - 1585 Abstract: A low-profile microstrip patch antenna (MPA) operating in triple WLAN bands (2.4 /5.2 /5.8 GHz) with stable broadside radiation is proposed by employing TM10, TM12, and TM30 modes. Firstly, the TM12 mode of the MPA could be excited at around 5.8 GHz by properly selecting its dimensions. Meanwhile, a linear slot is etched out at the center of the radiating patch to transform the radiated fields of TM12 and TM30 modes into the broadside radiation with low sidelobe level. Secondly, the shorting pins are symmetrically loaded underneath the patch, aiming to improve the input impedance matching of TM10 mode and push up its resonant frequency to around 2.4 GHz. Thirdly, a pair of parallel slots is near the radiating edges of the patch radiator, thus extending the surface current distribution of TM30 mode and reallocating its resonant frequency to around 5.2 GHz. In final, the prototype antenna is fabricated and measured to validate its working principle. The results illustrate that this low-profile MPA makes these three radiative modes resonate at around 2.44, 5.22, and 5.82 GHz, respectively. Most importantly, a stable normal radiation pattern with low cross-polarisation and sidelobe levels is maintained for the proposed antenna as well. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Elham Erfani;Safieddin Safavi-Naeini;Serioja Tatu;
Pages: 1586 - 1592 Abstract: A broadband and high gain transmit array (TA) antenna, operating at 60 GHz, is proposed. To meet the design requirements of a TA antenna with polarisation-insensitive radiation performance, an optimal multi-layer unit cell (UC) is introduced. The dimensions of the UC are parametrically expressed to realise a linear transmission phase response with a variation range of 270° and insertion loss PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Guru Prasad Mishra;Biswa Binayak Mangaraj;
Pages: 1593 - 1601 Abstract: This article proposes a new class of miniaturised microstrip patch design for wireless communications at 10 GHz. Antenna miniaturisation is achieved here by loading a highly capacitive modified Minkowski fractal (type-2) defected ground structure (MFDGS-II) exactly beneath the center of the radiating patch. The proposed methodology involves sensitivity analysis to select best DGS configuration. The resonant frequency corresponding to the patch is reduced from 16.832 GHz to 10 GHz incorporating MFDGS-II without any change in the physical size of the antenna. This enables a patch size reduction of as high as 68% and an overall volumetric reduction of 84% along with an improvement in bandwidth and efficiency of the antenna. A prototype of the proposed antenna is fabricated, and its performance parameters are measured. An equivalent transmission-line model is presented to explain the theoretical background behind the shift in the resonant frequency of the antenna. Our antenna prototype with a lower patch size of 0.20λ0 × 0.15λ0, exhibits an impedance bandwidth of 270 MHz, a realised gain of 3.2 dBi with radiation efficiency of 98% centered at 10 GHz. The proposed compact antenna has the potential to meet the practical requirements for portable X-band wireless sensor applications. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Hui Wang;Shaobo Qu;Mingbao Yan;Jiafu Wang;Lin Zheng;
Pages: 1602 - 1609 Abstract: In this article, based on the idea of the metamaterial designing, the authors present a design and analysis of a polarisation selective metasurface (PSM), providing a multi-band response. The proposed PSM is composed three metallic layers. The middle- and lower-level layers are formed of combinations of short and long metal wire with periodic arrangement and structural dimensions, while the upper layer is consisting of gridded square loops arrays. Among the three polarisation selective operating bands generated by PSM, the 3-db transmission is used as the threshold of the operating band. TE polarised wave passband bandwidth is 1.5 and 1.83 GHz, respectively, while TM polarised wave passband bandwidth is 1.13 GHz. In each passband, the insertion loss is PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Nidhi Pandit;Nagendra Prasad Pathak;
Pages: 1610 - 1619 Abstract: This study reports the design, development and analysis of centre frequency and bandwidth (BW) reconfigurable multi-mode band-pass filter with independently tunable transmission zeroes (TZs). The designed filter can tune lower TZ (TZ1) from 1.66 to 1.88 GHz (220 MHz) with lower-side BW tuning range 200-400 MHz and upper TZ (TZ2) from 2.32 to 2.48 GHz (120 MHz) with upper BW tuning range 430-630 MHz. The centre frequency of the designed filter can be tuned from 1.98 to 2.04 GHz (60 MHz). For the entire tuning range, the insertion loss of the designed filter is around 1.4-2.3 dB and return loss is better than 10 dB within the pass-band. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Brian S. Collins;
Pages: 1620 - 1625 Abstract: The study describes a small antenna with a hybrid loop-notch configuration. This format has very small dimensions in terms of the operating wavelength and operation is possible over two or more non-contiguous frequency bands. When integrated into a host circuit board it can be designed to maintain a substantially constant resonant frequency in the presence of obstructions such as the human body. A number of different simple feed arrangements are described, which can be adapted to suit other implementations. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Amit Kumar Baghel;Shashank Kulkarni;Sisir Kumar Nayak;
Pages: 1626 - 1636 Abstract: A parabolic profile pyramidal horn antenna with flaring in both the Eand H-plane is presented in this study. The proposed structure having aperture dimensions of 518.10 × 408.36 mm2 is designed and fabricated for S-band (2.2-3.3 GHz). Due to increase in the flaring by 3.35° in the E-plane and 3.18° in the H- plane compared to the optimal typical pyramidal horn antenna (TPHA), a half-power beamwidth (HPBW) of less than 16.20° in both the planes with higher gain is achieved in the proposed antenna. The maximum phase centre (PC) variation, phase and amplitude variation of the electric field across the aperture in the proposed design are half compared to TPHA throughout the band, thus having good PC stability and lower phase error. The cross-polarisation level and the measured return loss of PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Yasir I.A. Al-Yasir;Yuxiang Tu;Mustafa S. Bakr;Naser Ojaroudi Parchin;Abdalfettah S. Asharaa;Widad A. Mshwat;Raed A. Abd-Alhameed;James M. Noras;
Pages: 1637 - 1645 Abstract: This study presents an original asymmetric stepped-impedance resonator filter combined with meander coupled-line structures and enabling the realisation of finite transmission zeros (TZs) and the implementation of multi-band bandpass filters. The meander coupled sections (MCSs) tune the TZs and resonant frequencies: with higher-order spurious frequencies cancelled by the TZs, a single wideband with wide stopband from 1.18 to 1.84 GHz is possible. Furthermore, by positioning the finite TZs between the high-order spurious frequencies and adjusting the coupling strength between resonators, a quint-wideband filter can be realised, with centre frequencies of 1.19, 4.29, 5.43, 6.97, 9.9 GHz and fractional bandwidths of 31.9, 15.4, 15.8, 4.3, 39.2%, respectively. More importantly, two filters with single/quad-wideband performance can be realised by tuning the parameters of the MCS, and therefore they can be designed separately by using only one original structure. The triple-wideband filter is realised with the help of the asymmetric parallel uncoupled microstrip section. These filter structures enjoy the advantage of single/multi-band versatility, structure reusability and simplicity. The good in-band and out-of-band performance, low loss and simple structure of the proposed single/tri/quint-wideband filters make them very promising for applications in future multi-standard wireless communication. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Slawomir Koziel;Anna Pietrenko-Dabrowska;
Pages: 1646 - 1652 Abstract: Numerical optimisation plays more and more important role in the antenna design. Because of lack of design-ready theoretical models, electromagnetic (EM)-simulation-driven adjustment of geometry parameters is a necessary step of the design process. At the same time, traditional parameter sweeping cannot handle complex topologies and large number of design variables. On the other hand, high computational cost of the conventional optimisation routines can be reduced using, e.g., surrogate-assisted techniques. Still, direct optimisation of EM simulation antenna models is required at certain level of fidelity. This work proposes a reduced cost trust-region algorithm with sparse updates of the antenna response Jacobian, decided based on relocation of the design variable vector between algorithm iterations and the update history. Our approach permits significant reduction of the optimisation cost (~40% as compared to the reference algorithm) without affecting the design quality in a significant manner. Robustness of the proposed technique is validated using a set of benchmark antennas, statistical analysis of the algorithm performance over multiple initial designs, as well as investigating the effects of its control parameters that permit control efficiency vs. design quality trade-off. Selected designs were fabricated and measured to validate the computational models utilised in the optimisation process. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Ziyu Xu;Helin Yang;Qisheng Zhang;Linyan Guo;Zhengwei Yang;
Pages: 1653 - 1659 Abstract: Strong mutual coupling always exists between the elements of the antenna array, thereby affecting its radiation capability. For this problem, an efficient method for suppressing the mutual coupling of array elements and improving the radiation performance of the antenna is proposed. In this study, take the antipodal tapered slot antenna (ATSA) array, for instance, a set of split-ring resonators (SRRs) unit cells is incorporated into the design to reduce leakage of the side walls at first. With the adding of SRRs, the mutual coupling in the entire operating frequency band (1.4-10 GHz) gets reduced, and the maximum reduction of 35 dB can be achieved. In addition, in order to compensate for the gain reduction caused by the isolation material, the grooves and semi-circular dielectric lens were introduced to enhance the low- and high-frequency gain, respectively. The gain of the proposed ATSA array can be improved by ~3.2 dB. At last, the proposed ATSA array has broadband, high gain with lower mutual coupling properties. This decoupling and gain-enhancing mechanism can be applied to other antenna designs. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Junho Park;Sangwook Park;Wonmo Yang;Dong Gun Kam;
Pages: 1660 - 1663 Abstract: The authors proposed a folded aperture-coupled patch antenna (ACPA) on a flexible printed circuit (FPC) with vertically polarised end-fire radiation, suitable for fifth-generation millimetre-wave massive multi-input-multi-output (MIMO) systems. For low-cost implementation, antenna elements were fabricated on a single polyimide substrate. The fabricated FPC was first folded to implement a three-layer ACPA, and then the feed line was bent 90° to achieve end-fire radiation. Measurement of five antenna samples demonstrates that the resonance frequency lies between 27.7 and 28.3 GHz. Each antenna sample has the bandwidth ( S11 1.2 GHz. The measured antenna gain is 2.74 dBi at 28.1 GHz, and the difference between co- and cross-polarised radiation intensities is>15 dB in all directions of interest. To improve the impedance bandwidth and the gain further, they increased the distance between the patch and the aperture of the proposed antenna by folding the fabricated FPC multiple times without an additional layer. Experimental results confirm the bandwidth of 2.64 GHz (26.27-28.91 GHz) and the gain of 3.80 dBi at 28 GHz. Additionally, the 1 × 8-folded APCA array is simulated to verify the feasibility for a practical application of multi-beam massive MIMO technology. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Waleed Abdelrahim;Quanyuan Feng;
Pages: 1664 - 1670 Abstract: This study introduces a simple, compact broadband dual-band circularly polarised slot antenna suitable for the use in the compact universal ultra-high frequency (UHF) radio-frequency identification (RFID) reader devices and Global Positioning System (GPS) applications. The proposed antenna is fed using an open-end coplanar waveguide with an inverted `L' structure. To realise a broadband circular polarisation and good impedance matching, an inverted L-shaped strip line is inserted adequately into a square slot at the right centre of the slot toward the slot centre. The experimental results demonstrate that the proposed antenna exhibits a 10 dB return loss bandwidth of 552 MHz (716-1268 MHz) and 3-dB axial ratio (AR) bandwidth of 564 MHz (824-1388 MHz). Additionally, the antenna gains are 3.8 and 4.29 dBi throughout UHF RFID band and GPS band, respectively. The proposed antenna has a wide AR bandwidth, a compact size, and a simple structure. Furthermore, the proposed antenna is printed on one substrate layer with an overall size of 112 × 112 × 1.6 mm3, which makes it more practical for universal UHF RFID handheld readers and GPS applications. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Oluwole John Famoriji;Shitan Yang;Yang Li;Wenhao Chen;Akinwale Fadamiro;Zhongxiang Zhang;Fujiang Lin;
Pages: 1671 - 1677 Abstract: Reconfigurable antenna array has received a lot of attention in present-day wireless communication systems. In this study, a simple design of a four-element circularly polarised dual-frequency reconfigurable microstrip patch antenna array for millimetre-wave applications is proposed. The sequentially rotated series-parallel stub approach is employed in the feeding network design to provide symmetrical array elements positioning, and bringing about a good axial ratio of polarisation. Additionally, a matching branch per element is employed to generate spatial flexibility for element positioning and good impedance matching. Furthermore, due to high-cost constraints of Ka-band RF switches (such as PE42524 SPDT), switches are considered as transmission lines, and are placed within the fractal slots of each elements to reconfigure the frequency. The proposed array operates in two switching states: ON and OFF. Hence, it allows dual-frequency reconfigurability of 27 and 35 GHz for the ON and OFF states, respectively. A full array prototype was then fabricated on a Rogers R5880 substrate and tested in an anechoic chamber. Simulation and measurement results corroborate quite well in general. Patch antenna array gives much better result characterised by reconfigurable behaviour with associated return loss, radiation pattern characteristics, and PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Guoping Gao;Chen Yang;Bin Hu;Shaofei Wang;Ruifeng Zhang;
Pages: 1678 - 1683 Abstract: A novel quasi-Cassegrain metasurfaces (MS) antenna with wide bandwidth operating in 8 GHz band is proposed. Initially, the article demonstrates a complete set of working principles and design approach for the proposed antenna. Then, this antenna is optimised, manufactured, and measured. The profile of the antenna is further reduced by using the reflect-array based on MS, and the gain is improved by loading shielded vias. Note that the second resonant frequency generated from sub-reflector is utilised to extend the bandwidth. The measured results indicate that the antenna achieves the peak gain of 15.9 dBi, impedance bandwidth of 1.07 GHz, and half power beam width of 26° in E plane and 21.5° in H plane. It has a low profile of 26.5 mm (0.71λ0) and occupies an area of 120 mm × 120 mm (3.20λ0 × 3.20λ0). The article not only completes the antenna operating in 8 GHz band but also provides a reference for the design of the proposed quasi-Cassegrain antenna in microwave band. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Rohit Mathur;Santanu Dwari;
Pages: 1684 - 1689 Abstract: In this study, a compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna with reconfigurable band notch characteristics is presented. The key feature of the antenna is its novel dual-band notch technique which blocks worldwide interoperability for microwave access or wireless local area network band interference. The UWB-MIMO property is achieved by two square monopoles separated by grounded multi-branch T-shaped stub. The reconfigurable dual-band notch operation is performed by PIN diodes integrated in a parasitic resonant structure in the ground plane. The antenna has a compact size of 40 × 20 mm2, with the operating frequency band of 3-11 GHz, where port isolation is better than 15 dB. The MIMO performance is ensured by calculating envelope correlation coefficient for the isotropic, indoor and outdoor environment. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Chang-Hyun Lee;The Viet Hoang;Sang Wook Chi;Sun-Gyu Lee;Jeong-Hae Lee;
Pages: 1690 - 1698 Abstract: This paper presents a high efficiency and low profile quad-beam circularly polarised transmitarray antenna using metasurface. In order to improve the aperture efficiency, the small unit cell is employed to obtain the beam forming since the gain of multi-beam is higher and the feed antenna suitable for low profile transmitarray is selected. To further improve the aperture efficiency, the cells with high transmittance are located at the centre of metasurface to increase the transmission efficiency since the electric fields of the low profile transmitarray are more concentrated on the centre of metasurface than those of the high profile transmitarray. The unit cell of metasurface is stacked by optimising with equivalent circuit analysis and generalised sheet transition conditions that can confirm a multi-layer performance easily. The principle of superposition was used to easily calculate the phase set required for quad-beam forming. The designed metasurface is 17 × 17 array of four-layer unit cells of 0.25λ0 × 0.25λ0 size at 5.8 GHz. The finally designed antenna with circularly polarised quad-beam has the peak gain of 12.1 dBic at 5.72 GHz, and the aperture efficiency and 1 dB gain bandwidth were found to be 30.7% and 3.5%~5.5% at four beams, respectively. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Mehdi Taherkhani;Jalaledin Tayebpour;Soheil Radiom;Hadi Aliakbarian;
Pages: 1699 - 1704 Abstract: A quadrifilar helix antenna (QHA), with an improved isoflux radiation pattern for S-band satellite ground stations, is designed and fabricated. The performance of the antenna with respect to its beam pattern, axial ratio and efficiency is investigated. To have optimum coverage of a low earth orbit satellite rotating the Earth's surface with one fixed pattern ground station antenna, an ultra-wide beamwidth isoflux pattern covering the complete upper hemisphere is required. The presented QHA antenna not only satisfies the required beam shape but also its pattern stays unchanged within a wide bandwidth. Besides that, an efficient Wilkinson power divider as the antenna's feed is designed to match the input impedance of helices appropriately, resulting in efficiency enhancement to>85%. The measured results, which indicate the performances of the proposed antenna in terms of the reflection coefficient, radiation pattern and axial ratio, are in good agreement with the simulation results within 2 to 2.2 GHz frequency band. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Zhou Chen;Jin Shi;Kai Xu;
Pages: 1705 - 1710 Abstract: In this study, a power dividing network with negative group delay (NGD) and balanced-to-single-ended topology is proposed. The resistors connected with coupled lines achieve both the functions of NGD and isolation. Therefore, the approach is much simpler than the one for single-ended power divider with NGD function. Furthermore, the insertion loss of the proposed design is lower than those of the power dividers with a similar level of NGD. Theoretic and experimental investigations of the proposed design are given to guide the design. One prototype working at 1.8 GHz is designed and fabricated. The measured results show that the group delay, return loss, insertion loss, common-mode suppression, and isolation at the centre frequency are -1.1 ns, 20, 2.4, 15, and 17 dB, respectively. The measured results agree well with the analytical and simulated ones. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Zhuozhu Chen;Zhongxiang Shen;Jun Zhang;Gary Zhang;
Pages: 1711 - 1718 Abstract: This article presents an H-plane horn antenna exhibiting very wide bandwidth, low profile, and nearly end-fire radiation. A wideband coaxial-to-waveguide transition is proposed by employing ridged waveguide and metallic posts in order to enhance the bandwidth and to suppress the higher mode, respectively. An ellipse-shaped copper taper is extended along the horn aperture in order to obtain smooth transition from the aperture to free space. The proposed antenna can be fully embedded in a conducting platform. Simulated results show that the proposed conformal antenna achieves a very wide bandwidth from 3.4 to 18 GHz for VSWR ≤ 2.5 while retaining the antenna height of only 5.508 mm (0.062λ0 at the lowest operating frequency). Nearly end-fire radiation is obtained over the whole frequency band. The prototype of the conformal configuration with six antenna elements embedded into a large cylindrical platform is fabricated and tested, measured results are in good agreement with simulated ones. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Jianxing Li;Tayyab Ali Khan;Xianjia Meng;Juan Chen;Gantao Peng;Anxue Zhang;
Pages: 1719 - 1725 Abstract: This article proposes a design of a microstrip patch antenna with reduced radar cross-section (RCS) in a wide frequency band. The RCS of the patch antenna is reduced with the integration of an optimised coding metasurface. The coding metasurface is designed by placing artificial magnetic conductor (AMC) unit cells together to achieve a phase difference between 180 ± 37° within a wide frequency range. The out-of-band RCS for the proposed patch antenna is reduced>7 dB from 12.2 to 19.8 GHz, corresponding to a relative bandwidth of 48%, with a maximum reduction of 20 dB at 18 GHz. The operating frequency of the proposed antenna is 8.7 GHz and the RCS reduction is mainly in the Ku band. Both monostatic and bistatic RCS performance of the proposed patch antenna have been simulated and studied. The radiation performance of the proposed patch antenna is hardly influenced by the employment of the proposed coding metasurface. Details of the design considerations along with the simulation and measurement results are presented and discussed. The measured results are in a good agreement with the simulated ones, verifying the validity of the proposed antenna. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Shi-Chang Tang;Xue-Ying Wang;Qing-Yuan Lu;Jian-Xin Chen;
Pages: 1726 - 1731 Abstract: Here, a fully substrate-integrated dense dielectric patch (DDP) antenna and array is proposed. The DDP resonator based on high-permittivity substrate on the top layer is reasonably constructed and implemented by making full use of the printed circuit board (PCB) technology, whose characteristics are theoretically analysed in detail. Accordingly, the DDP antenna element operating at the dominate TM101 mode (cavity mode) is designed, which is fed by the substrate-integrated strip line (SISL) through a feeding slot. The slot resonant frequency is close to the TM101 mode of the DDP so that the antenna impedance bandwidth (BW) is extended. For further demonstration, a 1 × 4 array based on the DDP antenna element is designed and fabricated. The simulated and measured results are given, showing good agreement. The impedance BW for S11 PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Chenlei Chu;Xiaoping Liao;
Pages: 1732 - 1736 Abstract: This study reports a bent cantilever radio frequency microelectromechanical system power detector with improved linearity up to 1 W. The proposed device employs an upward bent cantilever for power detection. The novelty of this structure is that the bend of this kind in cantilever can realize the compensation for non-linear saturation at high power level effectively. As a result, the linearity will be improved on the condition of high power detection. An equivalent circuit model of mechanical principle is established to analyse the bent cantilever behaviour. The whole device is fabricated using GaAs microwave monolithic integrated circuit technology. The bent cantilever is constructed to overcome the stress gradient during deep etching releasing process. Measurement results prove the improved linearity from 100 mW to 1 W and the corresponding sensitivity is 2.8 aF/mW at 10 GHz. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Yutian Zhang;Alexander Weiran Pang;Martin James Cryan;
Pages: 1737 - 1741 Abstract: A photoconductive grounded coplanar waveguide (GCPW) millimetre-wave switch controlled by a single infrared light-emitting diode is presented. By converting a straight GCPW transmission line into an alternating stepped-impedance line structure, the proposed device shows an on-state insertion loss of PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Shailza Gotra;Gaurav Varshney;Rajveer Singh Yaduvanshi;Vinay Shankar Pandey;
Pages: 1742 - 1748 Abstract: A technique is proposed to obtain the dual-band circularly polarised (CP) response along with the miniaturisation of a singly fed rectangular dielectric resonator (DR) antenna. The miniaturised response is obtained by applying the metallic strips on the sidewalls of the DR. The specific format of the applied metallic strips excites the orthogonal degenerate modes. Thus, a dual-band CP response is obtained along with the miniaturisation of antenna. The proposed antenna is designed to obtain the small frequency ratio. The frequency ratio can also be tuned by changing the surface area of the applied metallic strips. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Yanning Yuan;Xiaoli Xi;Yuchen Zhao;
Pages: 1749 - 1755 Abstract: In this study, two compact ultra-wideband (UWB) frequency selective surface (FSS) reflectors, which combine the branch loading method with the design of the traditional FSS, are proposed for antenna gain enhancement application. The working mechanism of the proposed FSS reflectors is analysed by the equivalent circuit model. The first FSS reflector, which is a 10 × 10 array with 8.25 mm × 8.25 mm unit size, not only enhances the gain of the UWB antenna, but also guarantees a constant gain with only 0.5 dB variation across the whole operation band. To further reduce the reflector size, a more compact FSS reflector with 6.25 mm × 6.25 mm unit size is designed by printing similar patterns on both sides of a single-layer dielectric slab. Compared to the first structure, the second reflector can realise a 25% size reduction and the same gain variation in the entire UWB frequency range. The only compromise is a 0.5 dB gain decrease. Finally, a good agreement between the measured and simulated results proves the feasibility of the authors' design. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
Authors:
Giuseppe Salza;George Goussetis;Carlos Vicente;Savvas Kosmopoulos;Marta Reglero;Máriam Taroncher;Vicente E. Boria;Nikolas Sidiropoulos;Jaione Galdeano;
Pages: 1756 - 1759 Abstract: The power handling capability of helical resonator filters is studied by means of the parallel plate model (employed in the European Cooperation for Space Standardisation) and more rigorous modelling techniques (like the one available in the commercial software tool SPARK3D™) as well as through an experimental test campaign. The results indicate that the parallel plate model provides conservative power handling capabilities for this class of filters, while rigorous modelling can better capture the impact of the geometrical features on multipactor evolution. Although the accuracy of the estimated power handling depends on the knowledge of the practical secondary emission yield values, the use of such rigorous modelling tools enables the design of helical resonator filters with improved power handling capability by exploiting the large gap approach, therefore opening opportunities to avoid additional dielectric fillings. PubDate:
8 14 2019
Issue No:Vol. 13, No. 10 (2019)
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