A new decoupling structure in H-plane for Vivaldi antenna is proposed in this article. The ultra-wideband (UWB) decoupling structure is shaped like an short-ended E, placed between two adjacent Vivaldi antennas along the H-plane. At the same time, a series of bowtie patches with overlapping edges is introduced, and a row of grid-shaped metal strips with equal height is loaded on the edge of the patches. All structure improvements lead to working bandwidth increasing, the total length reducing, and a better decoupling effect in the lower frequency. The simulation results show that the decoupling structure works well in 1.9-4.6 GHz, and the S21 between the two adjacent antennas in H-plane can be reduced at most 17 dB, with less influence on the radiation performance compared to the original antenna array.
For the pursuit of solving the electrically large scattering problems quickly and efficiently, an algorithm combining multilevel characteristic basis function method (MLCBFM) and compressive sensing (CS) is proposed for calculating the radar cross section of electrically large objects. According to MLCBFM, the surface of the object is first divided into large subdomains. Similarly, more levels of small subdomains are obtained by multilevel division, and the characteristic basis functions (CBFs) of each large subdomain can be obtained by those of small subdomains. Then, the obtained CBFs are taken as the sparse basis functions of compressive sensing theory, and the total impedance matrix which includes all large subdomains is evenly extracted as a measurement matrix. Finally, the coefficient of the unknown current can be obtained by implementing a recovery algorithm. The results of numerical simulations show that the algorithm of MLCBFM combined with CS has the same level of accuracy but higher efficiency than the traditional MLCBFM.
This paper presents a novel approach to detect failure elements in antenna arrays using a multi-branch artificial neural network (ANN) based on compressed sensing (CS) framework. The approach comprises a pre-trained decoder for quick far-field power pattern calculation and an encoder for recovering the sparse signals of the excitations of failed elements. The decoder trains on data from randomly impaired arrays to learn to calculate the sampled far-field patterns, while the encoder predicts the excitations of failed elements by inputting a small amount of phaseless measurement. Numerical examples demonstrate the effectiveness of the proposed method in terms of computational efficiency and diagnostic accuracy.
In this article, we present a balanced dual-channel filter based on dual-mode square dielectric resonator (DR) with a short end at the bottom. In this case, the resonator acquires a compact size, while it still retains a high unloaded quality factor. The electric fields of the modes are half cut like the shape of DR. According to the field distributions of the applied degenerate modes (half-TE011 and half-TE101), the pair of feeding probes are placed on both sides of the DR to realize differential excitation. Compared with the single-end feeding scheme, the higher order mode adjacent to the two used modes disappears after differential feeding. This property is beneficial to alleviate the adverse effect of higher order mode on the stopband suppression of the filter. The two orthogonal modes of half-TE011 and half-TE101 provide the internal isolation between the two channels. Based on the above analysis, a balanced dual-channel dielectric filter is designed with the center frequency of 1.52GHz and 3dB fractional bandwidth (FBW) of 2.6% for both channels. Because the structure is completely symmetric, the Chebyshev filtering responses of the two outputs are the same, and the number of size variables is significantly reduced. The results exhibit that the balanced dual-channel filter has the features of low loss, small size and wider upper stopband suppression.
This paper investigates the orthogonal subspace projection-based adaptive anti-interference technique for polarization-sensitive arrays. The mathematical model of the polarization-sensitive array adaptive anti-jamming and the orthogonal subspace projection algorithm are introduced first, followed by the derivation of the orthogonal subspace projection anti-interference algorithm. The simulation results demonstrate that the orthogonal subspace projection algorithm can be effectively applied in the polarization-sensitive array, which may and deepen the null depth by 15 to 25dB and considerably enhance the anti-jamming performance of the spatial and polarization filtering.
This paper designs a low-voltage and high-efficiency folded-waveguide traveling-wave tube at E-band. Besides optimizing the size and the number of the periods, efficiency increasing methods have also been added into the FW-TWT. Simulation results illustrate that both output power and efficiency can be further increased. In the range of 81-86GHz, output power is over 110 W and the electron efficiency can exceed 9.5%.
This paper proposes an efficient knowledge-based neural network (KBNN) for multi-performance indexes modeling of antennas in multi-physical fields. It contains multiple branches that can model different electromagnetic performance indexes separately. Here the first branch for the S-parameter consists of a back-propagation artificial neural network (BP-ANN) with two hidden layers and a BP-ANN with one hidden layer. The second branch for the radiation pattern contains a BP-ANN with two hidden layers. The trained BP-ANN with one hidden layer in the first branch can provide prior knowledge of multi-physical fields not only for the BP-ANN with two hidden layers in the first branch but also for the second branch. Thus the requirement for labeled samples from multi-physical fields is reduced in the training processes of the two branches. The validity of the proposed model is confirmed with one numerical example of a waveguide slot array antenna.
This paper reports the design of a novel millimeter-wave antenna with single-layered geometry and low profile. The antenna is working under two resonate modes, i.e. patch and inverted-F antenna (IFA) modes. The patch and IFA are located in the same substrate layer, leading to a single-layered geometry. The dual resonate modes contribute to the wideband operation of the antenna. To improve the port isolation, an L-shaped metal strip has been introduced. The design concept has been experimentally verified by a Ka-band 2×2 array antenna.
PET(polyethylene terephthalate) is widely used in daily life. With food packaging production steadily increased all over the world, traditional drying for PET materials shows weakness. This work is based on dual-channel microwave power input, which realized PET drying with the minimum at -92kPa and microwave power range is 200W to 500W. Moreover, by means of program, adapting the solid state source to the drying chamber eventually obtains the connection between microwave characteristics and material properties. When the phenomenon of thermal runaway was prevented, the inhibition of reflection power made drying better and the highest temperature corresponds to the best point of moisture content.
In this paper, a millimeter-wave (mmW) wide band right-handed circularly polarized (RHCP) horn antenna is designed based on a polarizer with two 90 degree slots loaded on the inner wall of a circular waveguide. The antenna is fed by a standard rectangular waveguide WR-10 waveguide port, and the antenna excitation signal is converted from linear to circular polarization by a circular polarizer. The principle of the antenna is analyzed, the model is simulated and the parameters are optimized, and the design method for obtaining the left-handed circularly polarized (LHCP) antenna based on the RHCP antenna is given. The simulation results show that the reflectance of the antenna is not higher than -24.5 dB, the RHCP gain is greater than or equal to 13.0 dBi, and the axial ratio (AR) is not higher than 3 dB in the range of 84-110 GHz (26.8% relative bandwidth). The proposed antenna is broadband and circularly polarized, and can be widely used in broadband mmW applications.
Kramers-Kronig (KK) receivers are capable of retrieving complex signals by amplitude detection without the need for a coherent receiver. However, the performance of the traditional KK receivers deteriorates significantly due to the nonlinearity and memory behavior of the system when applied to millimeter-wave (MMW) wireless communications. To address this issue, an improved KK receiver based on the generalized memory polynomial model (GMP-KK) for MMW communication is proposed, which can simultaneously compensate for nonlinearity and memory effects. For verification, a 95 GHz W-band MMW transmission with 20 Gb/s QPSK signals over a distance of 3 m is demonstrated. The experimental results show that the GMP-KK receiver can achieve more than 3.5 dB EVM improvement over the traditional scheme, and a reduction in bit error rate (BER) from 2.8 × 10-2 to 2.50 × 10-3
Quasi bound states in the continuum (quasi-BICs) of localized spoof surface plasmons (LSSPs) have weak radiation loss and high quality factors (Q-factors). In this paper, a displacement sensor based on the quasi-BICs of the LSSPs is proposed. The unit cell of the metasurface contains a circular grating and a circular dielectric sheet, and a plane wave is normally incident on the metasurface. When the circular grating and the circular dielectric sheet are concentric, only TE1,1 can be excited, TE2,1 and above are BICs and cannot be excited; when the circular grating and the circular dielectric sheet are offset by a displacement, TE2,1 and above transform into quasi-BICs and can be excited. The Q-factors of corresponding modes are related to the displacement, which is the principle of the sensor. Simulation is carried out and the feasibility of the sensor is verified. The sensor has the advantages of ultra-compact and high sensitivity.
We present a dual-polarized hemispherical beam coverage antenna array in this paper. This antenna is composed of 5 units, and the beam of each unit covers a part of the hemisphere independently. To enhance the operating bandwidth, proximity-coupling feed structures are adopted in the antenna. A dielectric radome is assembled not only to protect the radiation structures but also to enhance the radiation performance. In addition, the negative effect of the radome is also suppressed by an optimization process. Finally, the simulated results show that the gain is above 3 dBi in almost hemispherical space in the operating frequency band, while the voltage standing-wave ratios (VSWRs) of all ports are below 2.
In this paper, a dual-band filtering power divider (FPD) based on double-layer circular substrate integrated waveguide (SIW) resonator is proposed. A three-port filtering power division circuit is constructed on a vertically electrically coupled double-layer circular SIW resonator, and a power divider with integrated dual-band filtering is realized. The simulation results show that the center frequencies of the two passbands are 26.3 GHz and 33.47 GHz respectively, the relative bandwidths are 5.92% and 6% respectively, and the minimum insertion losses of the two passbands are better than 0.52 dB and 0.47 dB respectively. Three transmission zeros are generated outside the double passband, and the out-of-band suppression at the zeros is better than 60 dB.
A periodic leaky-wave antenna (PLWA) can usually produce a narrow beam scanning in the backward and in the forward quadrants with frequency. However, a PLWA with a low permittivity may suffer from some stopbands (e.g., open stopband and the next coming stopband) and unwanted grating lobe, as the main beam scans through broadside and in the forward quadrant. Besides, it may also suffer from an unwanted grating lobe, which limits its single-beam scanning range. This talk discusses recent advances in the research on the suppression of two stopbands (the open stopband and the next coming stopband) and unwanted grating lobe in PLWA.
A broadband achromatic reflective metasurface is proposed. For the right-handed circular polarized wave, the reflected wave could keep the same chiral. The abnormal reflection angle is able to hold at 32° from 9.5GHz to 11.5GHz, corresponding of the relative bandwidth 19.02%. The work efficiencies can keep over 70% and the peak could reach to 83%. The designed metasurface can be applied to the antenna arrays and communication systems.
To meet the requirements of Ku-band T/R transceiver module for RF front-end of digital array antenna system, based on the breakthrough of four-channel dual-polarization meta-synthesis architecture design technology, channel high isolation anti-cavity effect design technology, HTCC substrate high-density integration technology, a Ku-band dual polarization high performance T/R module based on SIP package is developed. By designing a microstrip through-the-wall transmission structure to replace the traditional SMP connector, the design of wireless interconnection between radar system modules can be realized, which is beneficial to the system reconfiguration. At the same time, a new type of MEMS ring isolator is designed. The ring isolator is changed from a conventional three-port network to a five-port network, the invention has the advantages of low loss, high power, full shield, high processing precision and good consistency, and can effectively reduce the load traction phenomenon caused by the antenna matching problem, fully ensure the stability of the transceiver link. output power ⩾10W, receiving gain ⩾25dB, noise coefficient ⩽2.5 dB, and good amplitude-phase consistency satisfy systems engineering applications.
An instantaneous frequency measurement (IFM) module with 2000MHz instantaneous bandwidth was designed and fabricated. The classical interferometer phase-comparison is adopted and the delay line element in the microwave correlator is realized based on the stripline. The results show that compared with coaxial line and microstrip line, the stripline has good electromagnetic compatibility and producibility simultaneity. Firstly, this paper introduces the application of IFM receiver, gives the common methods of frequency measurement and then interferometer phase-comparison IFM is mainly studied. The scheme of the proposed module is given and the design of stripline delay line is described in detail. Some techniques such as serpentine routing and matching via are used to improving the microwave performance. The input and output return loss is less than -20dB within the operating frequency range for the interconnection of stripline and microstrip. Finally, the proposed IFM module realizes the frequency measurement accuracy up to 2MHz with 10-bit digital coding within 2000MHz bandwidth. And during the dynamic range of input power from +10dBm to -70dBm, the maximum frequency error is ±8MHz. Frequency measurement time is less than 150ns and the operating temperature range from -45℃ to +70℃. The specifications and performance of the proposed IFM module can meet many defense application requirements. It permits production of lightweight, modular, ruggedized and low cost systems that provide highly accurate instantaneous frequency measurement capability and high system sensitivity which allows for excellent detection ranges to accomplish the mission.
