In this paper, a symmetrical fixed-frequency scanning leaky-wave antenna with dual polarizations (DP) based on the gap waveguide (GW) is proposed. The antenna operates in 5G millimeter wave band and is comprised of two side-by-side GWs and 96 DP radiating elements. The antenna is simulated and measured, achieving the scanning range of exceeding 95° and a peak gain of 14.5 dBi at 26.5 GHz.
A dual-band reconfigurable frequency selective surface (RFSS) is designed using characteristic mode (CM) analysis. By observing the modal behaviors of the two basic structures (microstrip line and square ring), an appropriate combination of them forms the initial element with a bandpass feature. In addition, the PIN diode is placed in the middle of the microstrip line so that the element’s resonant frequency varies with its ON/OFF state. Full-wave simulation shows the design of dual-band RFSS operating at 8.8 GHz and 10.4 GHz, which validates the proposed CM design.
A compact antenna feeding calibration network is proposed in this paper, aiming to provide a versatile and reliable feeding calibration integrated network for X-band phased arrays. Based on gap coupling theory and series-fed structure, the proposed calibration network is realized by the multi-layer couplers and a serpentine feedline. Meanwhile, the isolated metal columns and metal shielding boxes are designed to effectively improve the mutual coupling. Experimental data indicate that the fluctuations of coupling amplitude and phase are below 4.7 dB and 1.5°, the voltage standing wave ratio (VSWR) of each network port is below 1.25 and the isolation at the antenna end is greater than 53 dB.
Compared with PIN diode, varactor diode has more flexible phase manipulation capabilities [1] , [2] . By integrating varactor diode on the reflective meta-atom and changing the reverse bias voltage of varactor diode, the reflective phase can be continuously adjusted from 0 to 2π to achieve reconfigurable functions [3] .
This paper proposed the design and implementation of a Ka-band eight-channel transmit beamformer for SATCOM phased array, which employs the 0.13-µm SiGe Bi-CMOS technology and the wafer-level chip-scale packaging (WLCSP) technology. By using the switched-type attenuator and the active vector modulated phase shifter, the beamformer only consumes a quiescent current of 180 mA under 1.6-V supply voltage. The measurements show that from 27 to 31 GHz, a single-channel gain of 19.4~22.7 dB and a minimal OP1dB of 9.3 dBm can be achieved. Meanwhile, the measured RMS gain error is less than 0.48 dB and the measured RMS phase error is below 2.6°. The total size of the chip is 5.2×5.6 mm2 including pads.
In this paper, a low-profile, light weight ultra-wideband array antenna based on tightly coupled dipole antenna element is investigated. A hybrid wide-angle impedance matching (WAIM) layer consist of a parasitic dipole layer and a frequency selective surface (FSS) layer is used to replace the traditional dielectric wide-angle impedance matching layer. The parasitic dipole and FSS are printed on thin dielectric substrate laminated with PMI foam, which can effectively reduce the antenna weight. The infinite array element achieves 6:1 bandwidth with VSWR ≤ 3 for scanning to ± 60° in E-plane and VSWR ≤ 3.5 for scanning to ± 45° in H-plane. The array element profile is less than one tenth of the wavelength of lowest operating frequency.
The previously established energy transport theorem (ETT)-based decoupling mode theory (DMT) for the wave-port-fed transmitting antennas is further extended to the wave-port-fed transmitting-receiving systems. This paper only considers the case of metallic transmitting-receiving system, and the obtained ETT-based DMT (ETT-DMT) will be further extended to the cases of material and metal-material composite transmitting-receiving systems in the future studies.
This paper proposes a 1×3 interconnected magneto-electric (ME) dipole array on a single layer of PCB substrate. The magnetoelectric dipole in the center is fed through the L-shaped coupled strip and two passive magnetoelectric dipoles on both sides along the E-plane are fed through microstrip lines. The ME dipole array achieves a simulated impedance bandwidth of 8.6GHz from 22.5GHz to 31.0GHz (30.7%). In addition, the simulated 3dB gain bandwidth is 6.6 GHz from 25.57GHz to 32.19GHz (23.6%). The proposed ME dipole array has the advantages of simple feeding structure, easy fabrication, low profile, light weight, and high gain.
This manuscript presents a novel polarization- reconfigurable metasurface antenna based on vanadium dioxide (VO2) films, which can be configured as left-handed or right-handed circular polarization (LHCP or RHCP) states or linear polarization (LP) state in the operating band. Firstly, a VO2-based reconfigurable polarization-rotation metasurface is proposed, which has a wide polarization-rotation bandwidth, and the structure exhibits full connectivity, which is convenient for applying DC bias to control the state of the VO2 film. Then, the proposed metasurface is used to construct a polarization- reconfigurable metasurface antenna, which is fed by a SIW cavity and coupled with a slot. The results show that the antenna has a good reconfigurability of polarization in the operating band with a low profile of 0.754mm. In LHCP/RHCP state, the 3-dB axial ratio band is from 28.6~29.5GHz (3.1%), and it is well matched over the entire band, with a maximum gain of 6.5dBi. In LP state, it operates from 29.6~30.3GHz (2.3%) with the maximum gain 7dBi.
This paper proposes a low profile circularly polarized Fresnel lens antenna for millimeter-wave (MMW) frequency band. The antenna consists of four parts: Fresnel lens, dielectric polarizer, folded structure and linearly polarized feed. The linearly polarized electromagnetic wave emitted by the feed is reflected twice in the folded structure to reduce the section height. When the wave propagates through the dielectric polarizer, it is be converted from linearly polarized wave to circularly polarized (CP) wave. After propagating the lens, the electromagnetic wave is converted from spherical wave to high-directional plane wave, thus realizing a low-profile, high-gain CP antenna. The simulation results show that the impedance bandwidth of the antenna reaches 50%, the highest gain is 26.17dBic at 67GHz, the AR bandwidth is 29.7%, and the section size is reduced by 39%. The antenna has excellent performance and has great application prospects in MMW long-distance communication.
The design of broadband metasurface with ferrite loading is proposed in this paper. The ferrite applied in this structure has high permittivity and permeability, which promoting the miniaturization of the metasurface and operation in low frequency region. Broadband characteristic is achieved through structure designs including slotting and adding periodical sawtooth. The optimized design has covered the reflection phase bandwidth from 270 MHz to 710 MHz (fractional bandwidth up to 90%). Besides, its electric size is only 0.034λ0 and the reflection coefficient magnitude is larger than 0.8. Furthermore, due to its symmetric design, the reflection coefficient of the metasurface is slightly affected by incident angle.
The receiver plays a very important role in the research field of deep space exploration and radio astronomy, and the cryogenic low noise amplifier (LNA) is the key component of their receiving system. The LNA's noise performance is greatly improved when operating at extremely low temperatures. In this paper, we designed a VHF/UHF cryogenic LNA. The LNA adopts the topology of two-stage cascaded amplification. By adopting the structure of series negative feedback and parallel negative feedback and accurate input and output matching, it not only realizes the optimization of input return loss and noise, but also broadens the operating bandwidth and improves stability. Based on this structure, the design of a broadband LNA with high gain, low noise, and better return loss is realized in this paper. This design is tested at 300 K, 77 K, and 15K respectively. The experimental results show that the gain of the VHF/UHF (100-700 MHz) LNA is greater than 32.3 dB, the return loss of the input and output ends are better than 10 dB, and the noise temperature is less than 95.83 K at 300 K, the noise temperature is less than 23.83 K and 17.90 K at the physical temperature of 77 K and 15 K, respectively.
In order to solve the problem of undershoot and non-monotonicity in the envelope fitting applied to frequency spectrum analysis, this paper proposed an improved envelope fitting algorithm based on linear interpolation. The improved algorithm performs envelope fitting on the non-stationary region of the original signal by combining the method of finding extreme values and linear interpolation, and rejects the non-monotonic extreme points to ensure the monotonicity of the envelope. For the stationary signal regions, the envelope can tightly wrap the original signal and retain the characteristics of the original signal. The simulation results shows that the method proposed in this paper can effectively fit the envelope of the original signal without undershoot regions.
This work introduces an all-meta high-gain folded reflectarray antenna (FRA) for mm-wave applications. The proposed FRA consists of a reflectarray aperture and a linearly polarized feed with a wide operating frequency band on the bottom layer, and a simple grid polarizer on the top layer. The simple polarized grid is a single-layer structure consisting of a series of parallel metal strips. The polarized grid has the ability to reflect one linearly polarized wave while transmitting its orthogonal linearly polarized wave. The reflectarray is composed of dual-polarization elements who have excellent orthogonal polarization isolation, and an open-ended waveguide is selected as the feed. According to the results of the simulation, the elements provide a significant phase variation of about 540° with low losses in the 200-240 GHz frequency band. Meanwhile, a wideband FRA with a size of 13.6×13.6 mm is designed and simulated. According to simulation results, the suggested FRA achieves a 3 dB gain bandwidth of 29.5%, a peak gain of 27.8 dBi, and a peak aperture efficiency of 48.4% at 220 GHz.
In this brief, an overview of recently published works related to on-chip passive components will be given. As the full potential of CMOS-based active devices has almost reached, it is more important to start looking into passive-inspired designs, which have a potential to demonstrate the performance of the silicon-based RF circuits beyond Moore's Law. In particular, design of minimized passive components, reflectionless filters and passive/active co- designs will be summarized.
The Carrier Aggregation multiplexer is essential for radio frequency (RF) front-end system to meet the demand of Carrier Aggregation higher data rates. With the number of filters in multiplexer increasing, the insert loss will increase with the additional phase shifter in signal channels, which adjusts the impedance mismatch between different filters. This paper presents a Carrier Aggregation bulk acoustic wave (BAW) pentaplexer, designed by a new approach to optimize the phase shifter network. This new topology reduces the quantity and stage of phase shifters, improving the insert loss in signal channel and flexibility to design multiplexer.
In this paper, we design a Rotman lens working in the UWB band (3.1-10.6 GHz) and investigated the frequency domain and time-domain performance. The lens is designed for a scan angle range of -30 to 30 degrees with six beam ports and eight array ports. The designed lens is loaded with power dividers to improve its broadband performance. The time-domain performance evaluated includes energy patterns, fidelity patterns, and energy correlation patterns. The measured results show that the worst fidelity in the beam direction can also reach 0.958 verifying that the designed lens has good pulse fidelity characteristics.
A novel regrown ohmic contact technique is proposed to improve the performance of GaN HEMT by decreasing the parasitic resistance, which features regrowth of n + GaN without any mask on the whole wafer and self-stopping etching of the n + GaN on the access region. Compared with the reference HEMT, this regrown HEMT demonstrates improved on-state performance with increased output current density as well as peak extrinsic transconductance and reduced knee voltage. In addition, the off-state characteristics and gate diode characteristics have not been significantly affected by the self-stopping etching. Both good on-state and off-state characteristics can contribute to a high RF power performance.
In this paper, a simple-structure single-fed wideband circular polarized (CP) antenna is introduced and fabricated. It consists of a classical printed stepped monopole, a substrate and a modified stepped curling-shaped ground plane on the backside. The stepped monopole mainly contributes to the wide impedance bandwidth realization. By introducing a curling-shaped ground plane and shifting the monopole a little left to realize proximity coupling with the end of curling-shaped ground plane and enhance the horizontal surface current distribution, wide axial-ratio (AR) bandwidth can be realized. Measured results of the fabricated antenna exhibit 115.1% (6.66 GHz, 3.25–12.06 GHz) 10-dB impedance bandwidth and 64.1% (3.83 GHz, 4.06–7.89 GHz) 3-dB AR bandwidth. The simple-structure, easy-fabricated and the wide CP bandwidth show the designed antenna a good potential in C-band application.
