This Letter presents a dual linearly polarised microstrip antenna for base station applications. Firstly, a dual-polarised metasurface-based antenna element employing differential feeding technology ...is proposed. The proposed antenna element achieves a simulated bandwidth of 11.6% for |S11| < −15 dB, mutual coupling better than 30 dB, and the cross-polarisation discrimination level over 35 dB. Secondly, based on the antenna element, a 3 × 3 antenna array is eventually presented, which was fabricated and characterised. The measured bandwidth is 12% for |S11| < −10 dB, and the port-isolation is over 25 dB. The superiorities of low-profile and high port isolation indicate that the proposed design is a promising candidate for sub-6G base-station applications.
This study introduces a fundamentally new approach to suppress mutual coupling among two closely-spaced vertical monopole elements of a multiple-input multiple-output antenna array. The 40 × 40 × ...1.27 mm decoupling and matching element consists of a single planar ring resonator acting as a stop-band filter along with two tuning strips printed on an ungrounded substrate surrounding a two-element co-planar waveguide-fed monopoles separated by 8 mm (λ0/16) at 2.45 GHz. Measurements reveal 14.2% bandwidth centred at 2.395 GHz over which the decoupling is below 20 dB, and −10-dB impedance bandwidth of 19.5% centred at 2.36 GHz. An improvement of 43 dB in isolation is observed at a frequency of 2.38 GHz. It is shown that the decoupled array provides a total realised gain of 1.69 dBi with excellent diversity performance as demonstrated by the low envelope correlation coefficient and improved link efficiency in highly-correlated channel environments due to the spatially orthogonal 3D radiation patterns. The capacity offered by the decoupled array is enhanced by 50, 22, 18 and 12% at signal-to-noise ratios of 5, 20, 30, and 50 dB, respectively, as compared to the coupled array in an urban micro-channel spatial model.
In this paper, various Low Noise Amplifier topologies presented for high frequency applications. Distributed amplifier, source degeneration, common gate, common source with inductive and resistive ...load discussed with their advantages and disadvantages. The effect of parasitic capacitances at high frequencies discussed. The tradeoff between the various parameters are discussed for the given topologies and comparison table comparing the parameters given in this paper.
Abstract
This work clarifies the gain/noise figure spectra of average power model Raman optical amplifiers in coarse wavelength multiplexed systems. The proposed model have a total received power of ...16.306 dBm, signal gain of 21.68 dB, and noise figure of 3.802 dB at the same operation parameters of the previous model which operated at length 0.2 km at the optical fiber coarse wavelength division multiplexing (CWDM) and transmitted signal power is 20 dBm. So the updates help us to greatly improve the system.
Due to the significant advancement of transmission networks and related technologies, optical communication with a large capacity is essential. In this study, a few-mode PbS quantum dot-doped fibre ...amplifier (FM-PQDFA) was developed and numerically studied. The amplifier can effectively amplify the linear polarisation (LP) signal modes, including LP01, LP11, and LP21, in the range 1100–1350 nm. The influences of the quantum dot (QD) doping concentration, fibre length, and signal power on the gain and noise figure (NF) of FM-PQDFA were investigated. In addition, the pump influenced the gain, NF, and differential mode gain (DMG). The results revealed that the gain, NF, and DMG can be optimised by adopting an appropriate pump light mode. When the signal and pump light modes were both LP01, the highest gain of 31.6 dB and lowest NF of 3.25 dB were achieved. LP11 pump mode was the optimal pumping mode to obtain the high gain, low NF and small DMG simultaneously.
•A low-noise broadband few-mode PbS quantum dots-doped fibre amplifier was proposed and numerically analysed. It can amplify LP01,s and LP11,s evenly in the band ranging from 1136–1316 nm. The gains were higher than 27 dB, the DMG was less than 1 dB and the NFs were lower than 3.35 dB.•The QD doping concentration, fibre length, and signal power are important parameters that affect the performance of FM-PQDFA.•The pump influenced the gain, NF, and differential mode gain (DMG) by affecting the overlap factor between the pump light mode field, signal light mode field, and the area of the doped material; and the gain, NF, and DMG can be optimised by adopting an appropriate pump light mode.•When the signal and pump light modes were both LP01, the highest gain of 31.6 dB and lowest NF of 3.25 dB were achieved.
A novel C + L band hybrid erbium-doped fibre amplifier (EDFA) using a two-stage configuration was proposed and demonstrated experimentally. The amplifier is composed of a 0.5-m long hafnium bismuth ...erbium co-doped fibre (EDF) to provide gain within the C-band and a 4-m long zirconia-based EDF to provide gain within the L-band. The proposed amplifier was examined based on the multi-wavelength input source. A parallel pumping distribution technique was used to mitigate the amplifier complexity. The C + L band amplifier achieved a gain flattening of over 55 nm bandwidth for the three levels of the input powers. A gain-flattening of roughly 10.9, 15.5, and 19.2 dB were obtained, respectively, for the input signal powers of −5, −10, and −15 dBm. An average noise figure of 6.4, 5.4, and 4.7 dB was achieved, respectively, for the input signal powers of −5, −10, and −15 dBm.
Ceramic (Ba0.55Sr0.45Ti1.01O3) – polypropylene polymer ER182 composites-based materials were applied for sub-THz range antenna lens application in telecommunications. Typical plano-convex -shaped ...lenses were simulated and measured with a standard rectangular waveguide at 220–330 GHz frequency band and applied on 150 mm on-air distance. The lens fabricated with ER182 polymer material increased the signal strength by 15 dB, ER182/7 vol% BST by 6 dB and ER182/30 vol% BST by −23 dB. Material loss tangent values were 0.008 for ER182, 0.034 for ER182/7%BST and 0.081 for ER182/30%BST. The directivity of ER182 material lens and WR3 waveguide combination was 26 dBi at 300 GHz.
Here, a near-zero permittivity (ε) and permeability (μ) metamaterial superstrate is presented as a decoupling structure for a multiple-input–multiple-output (MIMO) antenna. The proposed design offers ...peak isolation of 41 dB with reduced edge separation of 0.042λo at the resonating frequency. To verify the simulation results, the prototype of the proposed superstrate and antenna is fabricated and tested. The two-element MIMO antenna has −10 dB impedance band of 5.5–5.92 GHz with a peak measured gain of 7.41 dBi and efficiency above 78%. The measurement results ensure an isolation enhancement of 30 dB with a correlation coefficient of <0.26 within the operating band. The proposed method offers a good design technique for high gain and a closely packed MIMO antenna system for WLAN applications.
A self-diplexing mixed-coupling bandpass filter based on a single slotted substrate-integrated-waveguide (SIW) cavity is proposed. By etching a wide slot, two unequal half-mode SIW parts are ...constructed and then fed by four coaxial ports to realise two bandpass filters with different centre frequencies. Since this etched slot can serve as a divider and an isolator, a flexible frequency ratio of 0.60–1.66 and high isolation of better than 20.0 dB is achieved. By further cutting the other two narrow slots, four quarter-mode sub-cavities are obtained where the mixed coupling is induced in the pass bands and a transmission zero (TZ) is introduced at the stopbands. The coupling and TZ are controllable by simply adjusting the length of these cut slots, which makes the proposed design easily redesigned for practical applications. A prototype with a size of 0.59λ0 × 0.59λ0 × 0.03λ0 has been fabricated. The measured centre frequency, TZ, 3-dB bandwidth, and insertion loss of the lower pass band is 2.51 GHz, 2.96 GHz, 340 MHz, and 1.67 dB, respectively, whereas those of the upper pass band is 3.06 GHz, 2.53 GHz, 370 MHz, and 2.44 dB, respectively.
This Letter presents the design of a reduced aperture low sidelobe $4 \times 4$4×4 patch array whose aperture is much smaller than that of a conventional $4 \times 4$4×4 patch array since the spacing ...between adjacent elements is less than $\lambda _o/2$λo/2. Low sidelobes are achieved without implementing an aperture distribution. This results in more efficient patch elements of the array and therefore the overall gain is higher than that of a conventional array of the same aperture. Moreover, as patches are series-fed, the width of feed lines is not limited by patch impedances and no matching transformer is required in the design. The experiment shows that a gain of 15.3 dB at 16.5 GHz and a sidelobe level of −16.7 dB in the E-plane and −15.1 dB in the H-plane are achieved.