Multilayer grid polarizers for millimeter waves produced with photolithographic technology have been simulated. Polarizers have spectral bands of enhanced performance where polarization extinction ratio in decibels grows in proportion to the number of layers. Full-wave modeling is compared with three asymptotic models for subwavelength gratings using adjusted grating parameters. Random variations of interlayer spacings reduce the enhancement of polarizing performance, yet the latter continues to grow in proportion to the number of layers. Broadband signal detection is also considered.
This paper proposes a novel bandpass filter for L-band based on CRLH TL, which is mainly formed by coupling a high-pass characteristic module with a low-pass characteristic module in a cascade. The high-pass module consists of an interdigitated coupled line and a grounding via, owning to its singular characteristics, which the miniaturization is realized. The low-pass module is composed of a C-type resonator with high-low impedance lines, which can realize great sideband attenuation characteristics. To further improve its out-of-band rejection characteristics, a complementary split-ring resonator (CSRR) defective ground structure with single-pole attenuation characteristics is loaded, and a transmission zero is introduced at 2.5f0 out-of-band. The test results are in great agreement with the simulation ones, and the dimensions are only 0.20λg*0.22λg. Compared with other similar types, the filter proposed in this paper has miniaturization, great passband selection characteristics, stopband characteristics, and the advantage of low insertion loss.
A new compact nonuniform leaky-wave antenna (LWA) with left-handed elliptical polarization (LHEP), based on composite right/left-handed (CRLH) metamaterial operating in the range of 7-10.2 GHz is presented in the work. The nonuniform structure of a CRLH transmission line (TL) is realized by the placement of different configurations of inter-digital capacitor (IDC) in the form of sinusoid (SIN-IDC), on the top of metal wall of a half-mode substrate integrated waveguide (HMSIW). Balanced condition of the unit cells is provided by the change in slit width, amplitude and the number of SIN-IDC periods, as well as by relocation of two additional transition apertures arranged by both sides of SIN-IDC. Based on the known Hensen-Woodyard criterion, the optimal number of the unit cells was determined, when the gain coefficient varied from 7.5 to 9.8 dB in all of the operational range of antenna. The developed prototype of nonuniform CRLH LWA has the size of 8.1x115.2 mm. It is characterized by a continuous scan angle range equal to 117°. The maximum angle of rotation radiation pattern is -66° for backward radiation and +51° for direct radiation. The maximum efficiency of the antenna radiation is 85%, while the total one is 68%.
When a substation is struck by lightning, it will cause the ground potential to rise, which will further cause serious interference to the secondary cable. This article is based on the grounding grid established in the testing ground. The grounding copper bar is laid in the cable trench to connect with the grounding grid. At different grounding grid points, use a lighting current impulse generator to apply high current. At the same time, the grounding grid model is established by using the ATP-EMTP software. Through the combination of test and simulation, the influence of different lighting inflow locations on the protection effect of grounding copper bar is studied, and combined with the connection method of the grounding copper bar and the grounding grid, the protective effect of the grounding copper bar on the secondary cable under the impact of lightning current was analyzed. The research results showed that the laying of grounding copper bars can reduce the influence of interference voltage on the secondary cables under certain circumstances, but when there are multiple connection points between the grounding copper bar and the grounding grid, the current injection position is different, which will affect the voltage between the cable core and the shielding layer. At the same time, it will also affect the ground potential rise of cable grounding point in different degrees.
A 6-element MIMO antenna system is introduced in this paper for N77, N78, and N79 (5G) communication bands. The proposed antenna element is composed of a four-section coupled line folded antenna. The performance of this antenna element is improved by using a partial ground plane combined with the DGS between the different elements of the MIMO antenna. The separated single antenna in this case has a reflection coefficient less than -10 dB over the frequency band from 3 GHz to 5 GHz. For the complete MIMO configuration, the reflection coefficientis less than -7 dB over the same frequency band for all the antenna elements. On the other hand, the isolation between antenna elements in the MIMO configuration is greater than 15 dB. The values of the MIMO parameters are calculated. These parameters include the Envelope Correlation Coefficient between the different elements (ECC), Diversity gain (DG), Total Active Reflection Coefficient (TARC), Channel Capacity Loss (CCL), and Mean Effective Gain (MEG). Good results are obtained for the MIMO parameters where ECC < 0.006, DG = 10, TARC < -7, CLL < 0.6, and -3 < MEG < -8. These performance parameters of the proposed MIMO system indicate that this antenna is suitable for 5G applications. The effect of the human hand on the S-parameter is also investigated. The proposed antenna is fabricated and measured to verify the simulation results.
A bidirectional, circularly polarized antenna with a miniaturized design and broadband capabilities is proposed for consideration in WLAN 2.4/3.65-GHz, WiMAX 2.3/2.5-GHz, 4G, and 5G frequency bands. The frontside of the antenna consists of a hexagonal slot, a hexagonal patch, ten meander tips, and rectangular corner notches to achieve broad impedance and axial ratio bandwidth. The feedline on the backside of the antenna with accompanying shorting pin is offset to further increase the common bandwidth. Also, the four corners of the antenna substrate are removed to decrease the electrical size. The designed antenna is fabricated and measured to validate simulation results. From measured results the antenna has a -10-dB impedance bandwidth of 89.7% (1.60-4.20 GHz) and a 3-dB axial ratio bandwidth of 70.5% (1.80-3.76 GHz). The peak realized gain in the boresight direction is 3.65 dBi, which occurs at 1.88 GHz.