IET Microwaves, Antennas & Propagation
Volume 14, Issue 15, 16 December 2020
Volumes & issues:
Volume 14, Issue 15
16 December 2020
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- Author(s): Ankang Wang ; Xi Li ; Jiawei Zhao ; XiangJie Yi ; Lin Yang ; Yu Zhang
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1919 –1925
- DOI: 10.1049/iet-map.2020.0685
- Type: Article
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p.
1919
–1925
(7)
A circularly polarised (CP) monopulse waveguide antenna array for Ka-band wireless communication is proposed. The antenna structure can be divided into six layers from top to bottom, including radiating layer, aperture layer, cavity layer, aperture layer, feeding layer and monopulse comparator. The upper radiating layer allows two transmission modes of the transverse electric (TE) wave and the transverse magnetic (TM) wave to pass through. The 90° phase difference can be obtained by adjusting the horizontal and vertical angles of the horn radiator, which realises the CP radiation pattern. Besides, the 0° or180° phase difference produced by the monopulse comparator enables the antenna to obtain a monopulse radiation mode. In order to obtain the low sidelobe characteristics, the coupling parameters of the coupling layer are weighted by the Taylor distribution. The overall size of the antenna is 194 × 25 × 31 mm3. The slot waveguide antenna is fabricated and measured to validate the proposed design. The measured results show that the monopulse system can achieve an impedance bandwidth of 3.7% (34.5–35.8 GHz) in the Ka-band at the centre frequency of 35 GHz. The sum-pattern maximum gain and radiation efficiency are 23.3 dBic and 75% at 35 GHz, and the gain of the whole bandwidth is >20 dBic. The axial ratio and the sidelobe level is less than 1.2 and −28 dB, respectively. The difference-pattern amplitude imbalance is <0.2 dB and the null-depth lower than −30 dB. Also, the isolation is better than 30 dB. Besides, the pure metal structure of waveguide has incomparable advantages in a harsh environment.
- Author(s): Stefano Maddio ; Giuseppe Pelosi ; Stefano Selleri
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1926 –1932
- DOI: 10.1049/iet-map.2020.0450
- Type: Article
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p.
1926
–1932
(7)
This study presents a single-layer via-less antenna array operating in circular polarisation for wide-band operation in C-band. The antenna comprises disc based elements arranged in a sequential rotation architecture. Each element is tuned to exhibit multiple resonances with good circular polarisation performance over a broadband of frequencies. A proper feeding network is then designed so that the resulting array is capable of a wide-band operation and enhanced gain, equalising the frequency response of the set of elements. Simulations are validated by fabricating and measuring a prototype realised on a commercial FR408 dielectric substrate. Notwithstanding a dimension of only , that is only at centre frequency, measured performance of the proposed array can be summarised in a gain better than 7 dB over an operation bandwidth of , which is an unmatched result, given the via-less single-layer technology and the specific available area.
- Author(s): Lin Bai ; Xin Ge Zhang ; Qiang Wang ; Chen Xi Huang ; Wei Xiang Jiang ; Tie Jun Cui
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1933 –1942
- DOI: 10.1049/iet-map.2020.0415
- Type: Article
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p.
1933
–1942
(10)
The authors have proposed a dual-band reconfigurable Fabry–Pérot (F-P) cavity antenna with high gain and meanwhile small radar cross-sections (RCSs) in wideband. Different from the traditional F-P antennas, they used a dynamic metasurface reflective plane (DMRP) as the lower superstrate to realise reconfigurable functions and a digital coding metasurface as the upper superstrate to achieve wideband RCS reduction. To investigate the dual-band reconfigurability, a wideband rectangular waveguide is used to feed the F-P antenna. By varying the bias voltage applied to varactors embedded in the elements of DMRP, the reflection phase of DMRP is changed and the two operating frequencies can be tuned electronically. To realise RCS reduction, they adopted a meticulous arrangement of the coding elements on partially reflecting surface. The designed metasurface-assisted F-P antenna has good radiation performance with high gain, high aperture efficiency, and high radiation efficiency. In the experiments, a prototype was fabricated via printed circuit board technology, and measured results agree well with numerical simulations. The measured peak gain reaches 17.52 dBi and the maximum aperture efficiency is 56.97%. The two reconfigurable bandwidths cover 5.10–5.40 and 6.60–6.93 GHz, respectively; and 7 dB RCS reduction is achieved from 9.40 to 13.7 GHz for arbitrary polarisation
- Author(s): Tomas Mikulasek ; Jan Puskely ; Alexander G. Yarovoy ; Jaroslav Lacik ; Holger Arthaber
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1943 –1946
- DOI: 10.1049/iet-map.2020.0069
- Type: Article
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p.
1943
–1946
(4)
A novel basic antenna element for travelling-wave substrate integrated waveguide (SIW) arrays is proposed in this study. The antenna element is based on a transverse slot and newly complemented by a pair of vias used for matching and a phase shifter. By changing the geometries of the slot and the phase shifter, the amplitude and phase of a radiated wave can be controlled. The proposed approach extends the potential of transverse slots in SIW-based travelling-wave antenna arrays. To verify the capabilities of the antenna element, the authors demonstrate a six-element array with side-lobe suppression, intended for a 24 GHz radar system. The measured results show good agreement with simulations.
- Author(s): Niraj Agrawal ; Anil Kumar Gautam ; Karumudi Rambabu
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1947 –1951
- DOI: 10.1049/iet-map.2019.1153
- Type: Article
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p.
1947
–1951
(5)
An innovative design of a right hand circularly polarised (RHCP) antenna at two different resonant frequencies that is GPS (global positioning system) L2 and L5 has been proposed in this study. The proposed design comprised the concept of slotted radiator excited with a coaxial probe. Two asymmetric spiral slots were incorporated in a rectangular radiator to realise size miniaturisation, the axial ratio bandwidth and beamwidth at L2 (1.22760 GHz) and L5 (1.17645 GHz) frequencies of GPS applications. The proposed design has accomplished an excellent axial ratio bandwidth and beamwidth at both GPS L2 and L5 bands. The size of the designed antenna has been , which makes it attractive for the consumer market. Measured and simulated results achieved that the antenna conquered RHCP radiation at two separate operating bands, i.e. GPS L2 and L5.
- Author(s): Zhi-peng Li ; Lin Peng ; Jing Ma ; Bin Shi ; Qi-xiang Zhao ; Xing Jiang ; Si-min Li
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1952 –1959
- DOI: 10.1049/iet-map.2019.1129
- Type: Article
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p.
1952
–1959
(8)
Low-profile and wideband gain enhancement Fabry–Perot cavity antennas (FPCA) is proposed using gradient Partially Reflective Surface (PRS) and gradient Artificial Magnetic Conductor (AMC). A wideband source antenna is designed with a −10 dB impedance bandwidth of 58.1% (6.1–11.1 GHz). The PRS is constructed by a complementary frequency-Selective Surfaces (FSS) with a square hole and four small patches in a unit, which realizes phase increasing with frequency. The PRS and the AMC are gradient alone x-direction to achieve wideband phase compensation. While they are uniform in y-direction to realize better gain enhancement. Compared with the source antenna, the gain enhancement of the proposed FPCA is about 4–7 dBi. Moreover, the simulated and measured 3-dB gain bandwidths are 7.26–10.33 GHz (34.8%) and 6.8–10.8 GHz (46%), respectively. The gain enhanced bandwidth is about 52.3% (6.5–11.1 GHz). The impedance bandwidth is 6–11.1 GHz (59.65%). By using the gradient size AMC, the profile of the FPCA is reduced from 0.5λ 0 to 0.2λ 0, where λ 0 is the wavelength of 8.5 GHz. The proposed FPCA has the characteristics of wide impedance bandwidth, wide 3-dB gain bandwidth, wide gain enhanced bandwidth and low-profile.
- Author(s): Meng-Jie Hsiao and Cam Nguyen
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1960 –1968
- DOI: 10.1049/iet-map.2020.0439
- Type: Article
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p.
1960
–1968
(9)
A new ultra-wideband millimetre-wave passive balanced duplexer (DUX), employing a lumped-element Wilkinson power divider and grounded-centre-tap transformer, has been developed using 0.18-m BiCMOS process for fifth generation operations at 28, 37, 39 GHz, and beyond. The developed DUX is configured single-ended transmitter (TX) and antenna (ANT) ports and differential receiver (RX) port. It has an inherent matching at TX, RX and ANT ports, high TX–RX isolation, and highly balanced differential RX waveforms, and is ready for direct integration with a differential low-noise amplifier. Analysis has been performed to confirm the DUX's characteristics and assess its performance. Measured isolation from TX to each single-ended RX port is higher than 50 and 40 dB from dc-20 GHz and dc-60 GHz, respectively. Measured insertion loss from TX to antenna is better than 6.3 dB across 13–53 GHz. Measured insertion loss from ANT to differential RX port is lower than 13.8 dB from 25 to 57 GHz with 10.8 dB at 40 GHz. The core chip only occupies 0.3 mm2.
- Author(s): Bing Zhang ; Lin Zhou ; Qian Chen ; Li Wu ; Yanping Zhou ; Huacheng Zhu ; Yi Zhang ; Fei Cheng ; Ping Lu ; Kama Huang ; Yang Yang
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1969 –1974
- DOI: 10.1049/iet-map.2019.1126
- Type: Article
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p.
1969
–1974
(6)
A K-band (18–27 GHz) dielectric-loaded waveguide antenna is designed as the feed for a parabolic reflector. The antenna is composed of a waveguide launcher and a dielectric load. The waveguide launcher is fabricated by selective laser melting using aluminium alloy. The dielectric load is fabricated by stereolithography using resin. The aperture field distribution of the antenna is tuned by extending the E- and H-walls of the waveguide launcher to radiate a sidelobe-reduced main beam in the boresight from −90° to + 90°. The agreement is achieved between the simulation and measurement. It has impedance bandwidth of |S 11|<−10 from 18 to 27 GHz, the maximum gain of 11.8 dBi @ 19 GHz, and 3-dB gain bandwidth from 18 to 25 GHz. For the sidelobe reduced, simple design and low cost, the proposed antenna features a good candidate as the feed for a parabolic reflector.
- Author(s): Jun-Da Chen and Jia-bin Qian
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1975 –1982
- DOI: 10.1049/iet-map.2020.0287
- Type: Article
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p.
1975
–1982
(8)
This study presents an ultra-wideband up-conversion mixer chip that operates within the frequency range of 2–12 GHz using TSMC 0.18 μm complementary metal oxide semiconductor (CMOS) technology. The architecture is based on that of a Gilbert cell mixer. The design of the transconductance stage is based on an inverting amplifier. Two series resonant inductors are used to increase the conversion gain of the mixer, and a transformer that consists of two self-made inductors reduces the spatial requirement of the chip. This up-mixer achieves a 12.48 dB conversion gain and features an excellent gain flatness value of ±1.2 dB. The local oscillator (LO)-to-radio-frequency isolation is 44–20 dB, the input third-order intercept point (IIP3) is −6.8 to −8 dBm and the DC power consumption is 5.084 mW for a supply voltage of 1 V. The total size of the chip for the up-mixer is 1.2 × 1.2 mm2, including the pad frames.
- Author(s): Pooria Salami and Leila Yousefi
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1983 –1989
- DOI: 10.1049/iet-map.2020.0396
- Type: Article
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p.
1983
–1989
(7)
Although the ability of metasurfaces to control electromagnetic wavefronts has made it possible to design ultrathin carpet cloaks, the narrow operation bandwidth limits the performance of these cloaks. Here, the authors propose a new method to enhance operating bandwidth of metasurface-based carpet cloaks. The proposed cloak consists of super-cells providing appropriate phase shift to incident wave over a wide and continuous range of frequencies. Using the proposed method, a polarisation-independent wide-band single-layer carpet cloak is designed and fabricated. The performance of the proposed technique is verified using both numerical and experimental data. Experimental results show that the cloak operates well at all frequencies in the range of 9–10 GHz. The proposed method can be used for designing single-layer wide-band metasurface-based cloaks and illusion coatings at different frequency regimes.
- Author(s): Gang Zhang ; Shicheng Liu ; Zhuowei Zhang ; Chang Liu ; Yang Gao ; Jiquan Yang
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1990 –1997
- DOI: 10.1049/iet-map.2019.0842
- Type: Article
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p.
1990
–1997
(8)
This study presents a new reconfigurable quasi-elliptic filtering power divider (FPD) with tunable centre frequency (CF) and bandwidth (BW) by exploring singly one varactor-loaded triple-mode resonator. Avoiding the need for the variable couplings of the inter-resonant nodes and external input/output, the reconfigurability of the proposed FPD is achieved by only tuning the resonant nodes of the triple-mode resonator. Compared to the other reported ones, the proposed FPD not only exhibits better performance, but also compact and concise topology with the reduced number of resonators and loaded varactors. For demonstration, a prototype of tunable FPD is implemented following the given design procedure. Measured results coincide well with simulated ones, exhibiting that tunable CF (1.5–1.91 GHz), 1-dB BW (80–300 MHz) with better in-band isolation (>18 dB).
- Author(s): Xiaowen Zhang ; Guisheng Liao ; Zhiwei Yang ; Xintong Zou ; Ying Chen
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 1998 –2006
- DOI: 10.1049/iet-map.2019.0750
- Type: Article
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p.
1998
–2006
(9)
Processing conformal array signal is sensitive to antenna patterns on horizontal (H) and vertical (V ) planes while mutual coupling (MC) impacts distinctly on them. Many existing MC calibration algorithms ignore that and thus lose their efficacy. In this study, MC is modelled as distortions of H and V patterns. The direction-dependent and slowly varied properties indicate that MC can be estimated via sampling in the interested spatial range and calibrated. A novel MC estimation and calibration algorithm for all kinds of conformal arrays is proposed based on it. The process requires the use of three signals with diverse sets of polarisation emitted by a known calibrated source in each sampling direction. The selection of diverse polarisations is analysed in terms of optimisation and practical application. Simulations exhibit the potentialities of the proposed algorithm regarding the precision of MC estimation and the efficiency of calibration. It shows that significant superiority influences greatly in the analysis of conformal arrays.
- Author(s): Yu Wang ; Guo Liu ; Weijie Wang ; Chao Fang ; Zewei Wu ; Yong Luo
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2007 –2010
- DOI: 10.1049/iet-map.2020.0385
- Type: Article
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p.
2007
–2010
(4)
A periodic dielectric meta-surface structure was designed to extend the output window operating bandwidth of a wideband mode gyrotron travelling wave tube. The equivalent permittivity of the meta-surface matching layer can be adjusted arbitrarily by changing the lattice dimensions. The fabricated meta-surface dielectric window demonstrated a relative bandwidth of 53.9% with a reflection below in the Ka- and Q-band.
- Author(s): Sree Pramod Pinapati ; Joshua Brittain ; Adrian Caldow ; Christophe Fumeaux
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2011 –2019
- DOI: 10.1049/iet-map.2019.1025
- Type: Article
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p.
2011
–2019
(9)
An electromagnetic bandgap (EBG)-inspired low-profile wideband textile antenna is presented. By partially surrounding a standard textile patch antenna with mushroom EBG cells, a significant enhancement of the 10 dB impedance bandwidth is obtained. In particular, whereas a standard textile patch antenna exhibits a typical 10 dB bandwidth of 6% for a substrate thickness of 0.04, the proposed technique extends the 10 dB impedance bandwidth to 32%. Notably, the relatively large impedance bandwidth is achieved without extracting a heavy cost in terms of fabrication or design complexity. To make the design amenable for textile implementation, as opposed to more conventional designs which use EBG cells as a replacement for a ground plane, the proposed design hinges on the patch antenna being coplanar with a single quasi-ring of coplanar EBG cells. The proposed antenna design is validated through measurements in free space and on-body, where it is demonstrated to be robust to the effects of bending in the two principal planes.
- Author(s): Aslihan Aktepe ; Hüseyin Avni Serim ; Hüseyin Arda Ülkü
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2020 –2026
- DOI: 10.1049/iet-map.2020.0642
- Type: Article
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p.
2020
–2026
(7)
Analysis of transient scattering from impedance surfaces using physical optics (PO) approximation is presented. Specifically, a fast relaxed vector fitting scheme is applied to determine a weighted rational function fit to the surface impedance and associated functions in the frequency domain, then inverse Fourier transformed to the time domain in terms of decaying exponential functions. The scattered fields are obtained by convolving the time-dependent surface impedance (and associated functions) and the PO integral, which is determined via closed-form expressions obtained using the Radon transform interpretation. The numerical examples that demonstrate the applicability and validity of the proposed method are shown.
- Author(s): Amir Zahedi ; Farhad A. Boroumand ; Hadi Aliakbrian
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2027 –2034
- DOI: 10.1049/iet-map.2019.1117
- Type: Article
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p.
2027
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This work presents a new analytical transmission line model for microstrip T-resonator dielectric constant measurement method in order to simplify the extraction of the complex dielectric permittivity of the substrate and increase its accuracy. The proposed new formula, which is based on the T -matrix equivalent circuit of the structure, is only dependent on the propagation and attenuation constants of the stub line. Two new formulas to determine the end effect of open-ended stub and the propagation constant parameters are also presented. As an example, a T-resonator is implemented on a 31 mil RO4003C substrate, and it is simulated and measured S-parameter results in the range of 1 MHz–8 GHz are used to calculate a complex dielectric constant of the substrate at each resonance frequency. A full-wave simulation is also used to confirm the accuracy of the proposed model. The comparison between the simulated and the measured S-parameters demonstrates a relative error of <1% over the frequency range.
- Author(s): Sumantra Chaudhuri ; Mohit Mishra ; Rakhesh Singh Kshetrimayum ; Ramesh Kumar Sonkar ; Somen Bhattacharjee ; Bhaskar Saha
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2035 –2044
- DOI: 10.1049/iet-map.2020.0094
- Type: Article
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p.
2035
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A two-port planar dual circularly polarised microstrip patch antenna is presented. The designed antenna has two groups of patches, each for transmission and reception. In one such group, only the central patch with truncated opposite corners is probe-fed whereas the surrounding patches act as parasitic patches for bandwidth and gain enhancement. A defected ground structure (DGS) consisting 4 units of complementary square spiral resonators is used to enhance the port-to-port isolation as well as the axial ratio (AR) bandwidth. Based on the measured data of the fabricated prototype, the antenna is seen to have an impedance bandwidth of 900 MHz with the centre frequency of . Moreover, the AR bandwidth is measured to be 600 MHz at , whereas the peak gain within this band is found to be ranging from 6.8 to 7.9 dBic. It is also noted that the AR bandwidth lies entirely within the impedance bandwidth and the cross-polarisation discrimination is 20 dB in the boresight direction.
- Author(s): Goutam Kumar Das ; Subhadeep Basu ; Bappaditya Mandal ; Debasis Mitra ; Robin Augustine ; Monojit Mitra
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2045 –2052
- DOI: 10.1049/iet-map.2020.0083
- Type: Article
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p.
2045
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In this study, a metamaterial (MTM)-based high-gain compact-wearable antenna for 2.45 GHz industrial, scientific and medical radio band application has been proposed. To achieve the flexibility of the antenna, textile material felt fabric has been chosen as the substrate of the antenna as well as MTM. An omega (Ω) like structure has been taken as MTM unit cell design. High value of permeability is utilised for the gain enhancement of the antenna. In addition, very low specific absorption rate (SAR) is obtained using the MTM which makes the proposed antenna suitable for the biomedical application. The proposed antenna has achieved about 3 dB gain enhancement along with SAR value of 0.405 W/kg (1 g tissue). The design has been optimised and the prototype with the optimised parameter has been fabricated and tested over the semi-solid phantom and human body. Further, the proposed antenna over different type of textile material has also been validated.
- Author(s): Yasin Alekajbaf ; Nasser Masoumi ; Safieddin Safavi-Naeini
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2053 –2063
- DOI: 10.1049/iet-map.2019.0525
- Type: Article
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p.
2053
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This study presents a design and fabrication methodology for industrial broadband high power amplifiers (HPAs). The proposed method considers design constraints for broadband HPAs and parasitic effects arising from the fabrication process. This method is based on power combining networks (PCNs) whose characteristics such as power handling constraints, insertion loss, and bandwidth depend on the employed structure. Another important set of challenges is the technical faults and parasitics that occur during the fabrication process such as inequalities among different paths of PCNs, active and passive inherent mismatches, and many uncertainties in the fabrication and integration of a complicated large system. As such, the authors introduce a model for estimating the effects of path inequalities using a Gaussian function. For validation of the proposed methodology, a 2–6 GHz, 50 dBm output power broadband HPA system, which satisfies IEC-61000-4-3 RF radiant immunity measurement, was designed and fabricated. Furthermore, the measurement results exhibit the power-added efficiency of 10–28% and 48–51 dBm output power in the frequency bandwidth 2–6 GHz, which verify the capability of the proposed method for reliable estimation of the fabrication parasitics.
- Author(s): Abdul Samad ; Wei Dong Hu ; Waseem Shahzad ; Hamid Raza ; Leo P. Ligthart
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2064 –2073
- DOI: 10.1049/iet-map.2019.1024
- Type: Article
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p.
2064
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Metamaterial-based double-slit complementary split rectangular resonator sensor is proposed for the characterisation of dielectric properties of the materials under test (MUTs). The proposed sensor is designed and simulated on the CST microwave studio software using a low-cost substrate FR4. An array of three identical resonators is etched in the ground plane of the sensor to achieve a single and deep notch of −58.7 dB in the transmission coefficient (S 21) at the resonant frequency of 7.01 GHz, which is the novelty of the proposed sensor. A deep and single resonant frequency band has a significant role in the precise measurement of the dielectric properties of the MUTs. The effective constitutive parameters are extracted from the S-parameters. An equivalent circuit model is suggested that describes the overall behaviour of the sensor. The sensor is fabricated on the FR4 substrate and measured through the vector network analyser (N5224B) by placing the standard materials. The parabolic equation for the proposed sensor is formulated to approximate the permittivity of the MUTs. A very small percentage of error, 0.77, is found which shows high accuracy of the sensor. This methodology is efficient, simple in fabrication, and reduces cost and computational time also.
- Author(s): Tae Hwan Jang and Chul Soon Park
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2074 –2080
- DOI: 10.1049/iet-map.2020.0416
- Type: Article
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2074
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A novel type of wide-band long-wire antenna is presented for 60 GHz wireless on-board chip-to-multi-chip applications using a vertically polarised electric field. The psi-shaped structure is devised to match the antenna input impedance to 50 Ω and to increase the front-to-back ratio by placing two bent 0.5λ eff lines parallel to the original long-wire antenna, which resulted in improved realised gain and can be directivity compared to those of a conventional baseline structure. The psi-shaped long-wire antenna shows a peak gain of 10.2 dBi, an end-fire gain of 7 dBi, a 22% impedance bandwidth (52–65.2 GHz), and a 25.8% 3 dB gain bandwidth (56–74 GHz) in an area of 3.1 × 105 mm2. This study presents the proposed antenna for an on-board chip-to-multi-chip communication scenario for a distance of 20 mm, with a peak transmission gain of −19.5 dB and a 3 dB bandwidth of 11.8 GHz (=19.6%), which ranges from 55.4 to 67.2 GHz.
- Author(s): Hossein Nazemi-Rafi and Masoud Movahhedi
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2081 –2087
- DOI: 10.1049/iet-map.2020.0487
- Type: Article
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p.
2081
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A dispersive delay structure (DDS) is a device that creates a specified group delay function over frequency bandwidth. In this study, the idea of trapping the electromagnetic waves in a feedback loop is proposed to achieve higher group delay swing. The proposed structure includes two transmission lines and two junctions that act as power divider/combiner. The transmission lines can be either dispersive or non-dispersive. The group delay in the proposed configuration is proportional to the injected power into the feedback loop. So, an increase in the group delay swing can be done by improving the junctions or by adding more feedback loops to the structure. Based on this configuration, a novel DDS, using the substrate integrated waveguide transmission line, is introduced. According to the experimental results, the proposed device with a relatively compact size creates high group delay swings (9 ns), and its insertion loss is about 7 dB.
- Author(s): André Cruz ; Karlo Costa ; Victor Dmitriev ; Nadson Souza ; Quaid Zaman ; Tommaso Del Rosso
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2088 –2096
- DOI: 10.1049/iet-map.2020.0161
- Type: Article
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2088
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In this study, the authors present an electromagnetic model of a nanodipole array above a double-layer Graphene (DLG) operating at Terahertz. The graphene layers deposited between the dielectric mediums are modelled as surface impedances with conductivities described by the Kubo model. The electromagnetic fields are defined by the spectral representation of the periodic Green's function with impedance condition between the mediums. The main objective of this work is to propose an equivalent and analytical electromagnetic model of a nanodipole array above a DLG, which can be used to describe a surface plasmon resonance sensor that operates at the terahertz frequency. As a way of validating the method, the authors compared the proposed model with a software based on the finite element method. In addition, still, as a form of validation, the authors verified the convergence of the method from the spectral analysis of the proposed Green's Function. As results, spatial and spectral parametric analyses are shown as a function of the concentration of nanodipoles in the array, and the chemical potential applied to the graphene layers. In these results, the authors verify the appearance of plasmonic, optical and acoustic modes, and their contributions in the total field.
- Author(s): Jianxun Su ; Hang Yu ; Jiayong Yu ; Qingxin Guo ; Zengrui Li
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2097 –2101
- DOI: 10.1049/iet-map.2019.0938
- Type: Article
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2097
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This study presents a planar single-layer metasurface, with tri-band 10 dB radar cross-section (RCS) reduction under normal incidence for both polarisations, by employing optimised multi-element phase cancellation. The designed artificial magnetic conductor (AMC) unit cell is composed of an upper metal structure, a dielectric layer, and a bottom metal ground. When the dielectric constant and thickness of the substrate are fixed, regardless of any upper structure, the reflection coefficients of AMC are the same as the perfect electric conductor (PEC) at the short-circuit frequencies. Taking into account the multiple reduction bands that avoid short-circuit frequencies, a RCS reduction surface with a large frequency ratio is achieved. The optimised planar metasurface obtains 10 dB RCS reduction in the tri-band frequency (3.81–7.33, 19.16–22.83, and 35.63–38.37 GHz) with bandwidths of 63, 17, and 7.4%, respectively. Moreover, the bistatic scattering patterns between the proposed surface and the equal-sized PEC are investigated. The theoretically predicted, simulated, and measured results are in good agreement and provide a new strategy for achieving multi-band RCS reduction.
- Author(s): Haidong Chen ; Hongping Li ; Quan Xue ; Wenquan Che
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2102 –2109
- DOI: 10.1049/iet-map.2020.0443
- Type: Article
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2102
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This study proposes a compact structure of the three-way Gysel power divider with arbitrary power dividing ratio, which has a significant difference from existing N-way ones with a common node in the centre of the circuit. First, existing equations are reviewed, and new analytical closed-form equations are derived according to the proposed structure. The frequency bandwidths, affected by the parameters of isolation networks are investigated in detail and optimised for performance balance. For verification, the proposed three-way Gysel power dividers are calculated, optimised and fabricated at the centre frequency of 3.5 GHz with different dividing ratios of 1:1:1 and 1:2:3, respectively. Moreover, the equations are derived to design the N-way Gysel power divider.
- Author(s): Claudio Paoloni ; Rupa Basu ; Laxma R. Billa ; Jeevan M. Rao ; Rosa Letizia ; Qiang Ni ; Edward Wasige ; Abdullah Al-Khalidi ; Jue Wang ; Razvan Morariu
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2110 –2114
- DOI: 10.1049/iet-map.2020.0084
- Type: Article
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–2114
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High data rate wireless links are an affordable and easily deployable solution to replace or complement fibre. The wide frequency band available at millimetre waves above 100 GHz can support multi-gigabit per second data rate. However, the high attenuation due to rain and humidity poses a substantial obstacle to long-range links. This study describes a wireless system being developed for point-to-point links at D-band (DLINK), above 150 GHz, to enable a full fibre-on-air link with more than 1 km range and unprecedented data rate up to 45 Gb/s. The upper end of the D-band spectrum is used (151.5–174.8 GHz) in full frequency division duplex transmission. The DLINK system consists of a transmitter using a directly modulated resonant tunnelling diode oscillator powered by novel travelling wave tubes. The performance and the small footprint of the front end will make the DLINK system highly competitive to the point-to-point links presently available in the market at frequencies below 100 GHz. The innovative approach and the design are oriented to large-scale productions to satisfy the high data traffic demand of the new 5G infrastructure.
- Author(s): Yongwei Zhang ; Quan Shi ; Ahmed El-Makadema ; Laith Danoon ; Anthony K. Brown
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2115 –2122
- DOI: 10.1049/iet-map.2019.0869
- Type: Article
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An ultra-wideband phased array antenna using interconnected elements arranged in triangular lattices is investigated. The basic unit cell of the array is a dual orthogonal crossed ring structure. Each element is interconnected to its neighbour using capacitive loading. The ring structure on a planar surface produces broad frequency bandwidth with wide scan angles. Unlike other three-dimensional elements such as Vivaldi antennas, the interconnected crossed ring elements can be readily configured on a triangular grid. As is well known from narrow band arrays, a triangular grid allows reduction in the total number of elements needed for a given performance compared to a square grid. The array presented here applies the triangular grid to a broadband planar structure to reduce the total number of elements required by 13% while the electromagnetic behaviour of the array is essentially maintained. An array prototype of the design has been manufactured and tested. The performance is compared to the associated array with a regular square lattice. The proposed triangular grid structure is shown to be an effective solution for applications where a minimum number of elements is required for large-scale broadband dual-polarised antenna arrays.
- Author(s): Frederick Huang ; Pietro Bolli ; Sergio Mariotti
- Source: IET Microwaves, Antennas & Propagation, Volume 14, Issue 15, p. 2123 –2132
- DOI: 10.1049/iet-map.2019.1113
- Type: Article
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The higher order resonances of microwave superconducting filters with spiral resonators were suppressed, giving a very wide stop-band. In one filter spirals were modified to have equal fundamental resonances, but different higher order resonances, by adding stubs and using non-uniform line width. The higher resonances were reduced to −39 dB, in a stop band up to 4.3 times the pass band centre. In another filter, parasitic resistive resonators were added, suppressing the responses to −57 dB. The resistance is provided by patterning the 200 nm gold overlay already required for the external contacts. The increase in pass band loss is not measurable. Measurements of a single spiral resonator with a gold-YBCO bi-layer (200 and 600 nm respectively) suggest that the resistivity of the gold layer at 15 K is the order of 22 times that of bulk gold, a slight advantage for the present application. At 100 K, it is about double.
Low sidelobe level circularly polarised monopulse slot waveguide antenna array for Ka-band application
Circularly polarised sequential array with enhanced gain and bandwidth for applications in C-band
Dual-band reconfigurable metasurface-assisted Fabry–Pérot antenna with high-gain radiation and low scattering
Transverse slot with control of amplitude and phase for travelling-wave SIW antenna arrays
Design of single-fed spiral-shaped slotted planar antenna for GPS L2 and L5 applications
Low-profile and wideband gain enhanced Fabry–Perot cavity antenna using gradient PRS and AMC
25–53 GHz ultra-wideband high-isolation passive balanced duplexer on 0.18-μm BiCMOS for 5G applications
Metallic and dielectric hybrid 3D printed K-band dielectric-loaded antenna with reduced sidelobe
Low-power up-conversion folded CMOS mixer for 2–12 GHz ultra-wideband applications
Wide-band polarisation-independent metasurface-based carpet cloak
Reconfigurable quasi-elliptic filtering power divider with continuously tunable centre frequency and bandwidth
Effective mutual coupling estimation and calibration for conformal arrays based on pattern perturbation
Millimetre-wave design and verification of a meta-surface dielectric window made of polytetrafluoroethylene in Ka- and Q-band
Wearable textile EBG-inspired bandwidth-enhanced patch antenna
Transient analysis of scattering from impedance surfaces using physical optics approximation
Analytical transmission line model for complex dielectric constant measurement of thin substrates using T-resonator method
High port-to-port isolation dual circularly polarised microstrip patch antenna with multifunction DGS
Gain-enhancement technique for wearable patch antenna using grounded metamaterial
Design and fabrication methodology for industrial broadband high power amplifiers
Design of highly sensitive complementary metamaterial-based microwave sensor for characterisation of dielectric materials
60 GHz wide-band psi (Ψ)-shaped long-wire antenna for wireless on-board chip-to-multi-chip communication
Substrate integrated waveguide dispersive delay structure based on wave trapping
Electromagnetic model of a nanodipole array above a double-layer graphene by periodic green's function
Tri-band radar cross-section reduction based on optimised multi-element phase cancellation
Compact three-way Gysel power divider with arbitrary power dividing ratio
Long-range millimetre wave wireless links enabled by travelling wave tubes and resonant tunnelling diodes
Triangular grid interconnected crossed rings antenna for large-scale ultra-wideband dual-polarised arrays
Suppression of spurious harmonic responses in superconducting microstrip spiral filters using gold overlay and stagger tuning
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