The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In this paper, we discuss the limitations of phased arrays for 5G massive MIMO systems. The multibeam radiation patterns produced by a full phased array, a phased array with fixed sub-arrays, and a phased array with segmented phased sub-arrays are compared via illustrative examples. In fact, conventional phased array can only improve the link gain or the coverage, but couldn't enhance the capacity...
A substrate integrated waveguide (SIW) cavity-backed slot antenna with circularly polarized radiating pattern is presented. Four circular radiation slots and four insert metallic via arrays are introduced to from the radiation waves. Some metallic vias in the center of the cavity are set to prevent the fundamental mode. The proposed antenna have the advantage of a compact structure and high axial...
The design of a low-phase-noise local oscillator (LO) module for RF transceivers which support the very high throughput mode of IEEE 802.11ac standard is presented in this paper. This LO module provides both intermediate frequency (IF) LO and radio frequency (RF) LO by using HMC83x series chips. Low pass filters and amplifiers are used to improve output power and suppress harmonics of LO signals....
This paper presents the design of RF receiver operating in 5.0GHz to 6.0GHz band for high throughput IEEE 802.11ac system. A double-conversion super-heterodyne architecture with IF of 1.05GHz is employed and the maximum bandwidth is 80MHz. Measurement results show that the receiver has excellent performance. The noise figure is about 4.6dB and the gain flatness over any 80MHz bandwidth is less than...
In the field of high-speed wireless LAN, IEEE 802.11ac is gradually becoming the mainstream standard. Based on the main requirements of IEEE 802.11ac standard, this paper provides details on how to implement the high performance RF transmitter working in 5GHz to 6GHz band, which can support the very high throughput (VHT) mode of the standard. The maxim bandwidth of the transmitter is 80MHz and 256-QAM...
Implementation of a wideband RF transmitter is reported in this paper. In order to achieve the best performance, a super heterodyne architecture with RF of 14GHz and IF of 1.6GHz is employed, and the signal bandwidth is 1000MHz. Finally, measurement results of the transmitter are provided and the overall system performance indicated by EVM (Error Vector Magnitude) with 100MHz signal bandwidth (maximum...
A design of broadband multiple-input and multiple-output(MIMO) millimeter wave transceiver system is developed in this paper. The millimeter wave(mm-wave) transceiver system includes the ultra-wide bandwidth baseband data processing unit (BAP), intermediate frequency module (IF), mm-wave frontend and the power module. The developed system can support 4×4 MIMO configuration. The mm-wave frequency of...
In this paper, a wideband circularly-polarized patch antenna is presented. The patch is fed by four probes arranged by sequential rotation arrays, the four probes are connected to a feed network comprising of a pair of broadband 90° phase shifter and Wilkinson power divider. The proposed antenna shows a compact low profile, wide axial-ratio (AR) bandwidth, wide reflection coefficient bandwidth, as...
These paper proposes a Ka-band quadruple filter with coplanar waveguide (CPW) line to implement negative cross-coupling structure, which can obtain a single pair of transmission zeros (TZs) to improve stopband performance. Position of TZs can be adjustable according to the length of the CPW line, which decides the negative cross-coupling coefficient between the nonadjacent cavities. Compared to the...
In this paper, a 1×8 active antenna array based on frequency shiftable vector modulator (FSVM) module is demonstrated. The FSVM module can flexibly shift the operating frequency band of the vector modulator (VM) while not deteriorating the signal performance. By employing the FSVM module, a 1×8 active antenna array with a RF path beamforming structure is developed. Since the magnitude and phase of...
In this paper, the wideband digital predistortion (DPD) and the Zhu's general sampling theorem (ZGST) are applied to compensate the nonlinear characteristics of a wideband RF power amplifier with memory effects. In order to utilize the ZGST, the DPD test bench is carefully designed after analysis with the ZGST. The power amplifiers are excited by a long term evolution advanced signal with up to 100...
This paper presents a method to expand the bandwidth of conventional class-F power amplifier. Analysis indicates that small characteristic impedance of quarter-wave shorted-circuit transmission line in the harmonic control network is beneficial for PA design, as the second harmonic impedance varies less with frequency variation. A 10W GaN packaged transistor is used to verify the proposed method....
In this paper, a fast calculation method is proposed to calculate the output nonlinear distortions of the weakly nonlinear system stimulated by practical signals. The weakly nonlinearity is characterized by a third-order quasi-memoryless polynomial which is widely used and there are no assumptions on the statistical properties of the driven signals. The output is orthogonalized using Gram-Schmidt...
The design of a highly efficient dual-band power amplifier operating at 2.1 GHz and 2.6 GHz is presented in this paper. The output matching network is constituted with two parts, one is used to control the harmonic impedance, and the other is to match the 50 Ω load to the targeted fundamental impedance at this two frequencies. The harmonic controlled network is implemented with short-circuited and...
The design of a dual-channel broadband millimeter-wave receiver front-end for the next generation mobile communication is presented in this article. The front-end operates at 28GHz with 2GHz and 500MHz bandwidth in radio frequency (RF) and immediate frequency (IF) respectively. A scheme of single downconversion is used and a compact substrate integrated waveguide (SIW) bandpass filter is designed...
This paper describes recent progress on the investigation of scandate cathodes at BVERI. The key factors related to the cathode emission performance will be discussed. The application results of scandate cathodes in linear inductance accelerator (LIA), sheat beam TWTs (SBTWTs), electric thrusters and coaxial magnetrons will be presented.
This paper introduces the investigation of high performance Nickel-Oxide cathode for high powerw with long pulse. The authors also discuss the key factors affecting the performance of cathode, including the cathode surface, porosity of Nickel matrix, and distribution of temperature, etc. the authors employ the special mould to change the density and roughness of cathode surface. Finally, the magnetron...
In this paper, a novel architecture of a digital RF transmitter for the future massive MIMO system is proposed, which features flexible deployment, low cost, small volume and power efficiency. The comparison with a traditional architecture is also provided. To evaluate the feasibility of the proposed architecture, a prototype of one radio channel is implemented. The prototype consists of a BBU (Base...
This work reveals the design for broadband GaAs Class-F power amplifier employed in terminal applications. The approximated continuous Class-F mode was analyzed and applied to GaAs device. A harmonic matching network was used to realize a broadband fundamental load impedance match while the second and third harmonic impedance are kept inside the high-efficiency region on the edge of the Smith chart...
This paper describes the experiments for the evaporation and film degradation of osmium-coated cathode. Evaporating rate and under-heated characters were tested, and SEM & EDS were used. Barium evaporation is the main factor of cathode life degradation under 1080 C. The model of failure caused by evaporation was established.
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.