查看更多>>摘要：The use of advanced digital signal pro-cessing(DSP)technology in the high-speed terahertz(THz)communication can effectively compensate the lin-ear and nonlinear effects of the system and further im-prove the transmission performance of the system.This paper introduces the principle and application of ad-vanced DSP algorithms such as probability shaping(PS)technology,Volterra series nonlinear compensation al-gorithm,Kramers-Kronig receiver,look-up table(LUT)pre-distortion compensation technology,pre-equalization and decision-directed least-mean-square equalization al-gorithm.Combined with DSP algorithms such as PS and LUT pre-distortion,using photon-assisted technology to successfully realize the wireless transmission of vector THz signals higher than 1 Tbit/s on the sub-THz band(D-band)4×4 multiple input multiple output system.
查看更多>>摘要：The research on high power 170 GHz frequency doubler based on the GaAs Schottky diodes is proposed in this paper.This basic doubler cell is de-veloped with a 50-μm-thick,600-μm-wide,and 2-mm-long AIN substrate with high thermal conductivity to reduce the thermal effect.Besides,power combined frequency doubler has been fabricated to improve the power capa-city by a factor of two.Great agreement has been achieved between the simulated results based on electro-thermal model and measured performances.At room tem-perature,the 3 dB bandwidth of the single doubler based on GaAs Schottky diodes is 11.8％over the frequency range from 160 to 180 GHz with pumping power of 150 to 330 mW.And the peak efficiency of the doubler is meas-ured to be 33.1％,while the maximum output power is 101.7 mW at 174.08 GHz.As for power combined circuit,the best efficiency is 30.1％with a related output power of 204.6 mW.The proposed methods of developing high power multipliers can be applied in higher frequency band in the future.
查看更多>>摘要：This paper presents an E-band reflector antenna fed by dual circularly polarized feed system.Axi-al displaced ellipse reflector is adopted for high gain and low blockage mechanisms.The feed system mainly com-posed of orthomode transducer,iris polarizer and horn antenna,and possesses dual circular polarization.The or-thomode transducer offers high isolation performance in broadband by double symmetry and the iris polarizer achieves phase shift by introducing discontinuities.In ad-dition,the ridge and iris in the feed are optimized to be wide enough to fabricate and maintain good mechanical properties in higher frequency band.The entire antenna is simulated and fabricated.The measured gain of 45±1.2 dBi corresponds to about 52％efficiency.The measured res-ults of reflection coefficients less than—18 dB,isolation over 27 dB,axial-ratio value less than 2.3 dB are achieved from 71 to 86 GHz.
查看更多>>摘要：In this paper,A 220 GHz orthogonal modulator based on two symmetrical subharmonic mix-ers is designed,analyzed and measured,where the mixers are implemented basde on antiparallel Schottky diodes.The orthogonal modulator consists of a 90° phase shifted 220 GHz 3 dB coupler,two sub-harmonically pumped mixers and an in-phase 110 GHz 3 dB power divider.The IF output signals are in-phase(Ⅰ)branch and quadrature(Q)branch operating from DC±3.5GHz.In the back to back experimentaltests,it is shown that the conversion loss of the two 220 GHz I/Q mixers is less than 30 dB when the IF operating frequency is DC—3.5 GHz,IF in-put power is—10 dBm and the LO power is around 6 f mW.Based on floating-point simulation,the amplitude]and phase imbalance of the I/Q mixer are less than 0.2 dB and 2 degree respectively.When the 220 GHz modu-lator and demodulator are set in a back to back configur-ation,a signal-to-noise ratio of 21 dB can be obtained us-ing the 16QAM modulation type.
查看更多>>摘要：This paper presents the research on a 220 GHz multi circuit inte-grated front end based on solid-state circuits.This integrated front end integrates a 220 GHz subharmonic mixer,a 110 GHz tripler,a 110 GHz 8 dB hybrid coupler and a 220 GHz waveguide bandpass fil-ter(BPF)in one single block.Compared to the tradition-al transceivers which usually use cascade connection of the independent mixers and multipliers,the size of the proposed multi circuit integrated front-end block is 25 mm×20 mm×20 mm,ten times smaller than the cas-cading transceiver.In order to check the tripler's output power,a modified compact 110 GHz 8 dB hybrid coupler is set between mixer and tripler.Due to the characterist-ics of the hybrid coupler,the deterioration of cascading transceiver's performance caused by mismatch has also been improved.In addition,to achieve single sideband(SSB)communication,a 220 GHz BPF with high selectiv-ity is integrated in the circuit.The measured conversion loss of the fabricated multi circuit integrated front end is less than 11 dB,where the LO and RF frequency are 37 and 210-220 GHz.Based on this front-end,a 220 GHz high speed communication system has been setup and it can achieve 10 Gbps data transmission using 16QAM modulation.
查看更多>>摘要：A reflective phase shifter is proposed to realize the two-dimensional beam-scanning reflectarray.The reflectarray is composed of double-dipole resonant elements in which the phase shift is implemented by ap-plying a driving voltage to the liquid crystal(LC).A 30×30 phase shifter sample is fabricated on a quartz sub-strate with a 480 μm thickness and a 4 cm × 4 cm area.According to the experimental results,0 to 360° phase shift can be achieved within the bandwidth of 5 GHz.In order to accomplish two-dimensional beam-scanning and reduce the negative impact of driving lines on the reflec-tarray,a new LC driving method is developed.To verify the accuracy of the proposed approach,three samples of different driving line numbers are designed using the above-mentioned phase shifter,which all have achieved a 0-360° phase shift in the bandwidth of 4 GHz.Consider-ing the influence of LC anisotropy and inhomogeneity,an improved calculation result is obtained and compared with experimental data.
查看更多>>摘要：As the carrier frequency goes into the terahertz band,the phase noise of the signal source has increasing impacts on the performance of the communica-tion system.Considering a 16QAM high-order digital modulation terahertz communication system(DMTCS),by comparing the influence of two kinds of local oscillator signal sources with different phase noise characteristics on the bit error rate(BER)performance of the system based on theoretical analysis and experimental research,it is found that the near-end phase noise of local oscillator sig-nal source has a great influence on the BER performance of the DMTCS.The suppression of phase noise of the loc-al oscillator signal source based on choosing loop band-width of the digital phase-locked loop(DPLL)at the re-ceiving end is also discussed.It is found that the negative impacts of phase noise on BER performance of the sys-tem can be efficiently decreased by reasonably selecting the loop bandwidth of the DPLL.
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