The research on reconfigurable antennas has some disadvantages such as low working frequency and large size. This paper presents a Ka-band patch antenna with pattern reconfigurability using RF MEMS switches. The antenna contains one main patch, two sub-patches, two parasitic patches, and two RF MEMS switches. By controlling the states of the RF MEMS switches, the antenna can achieve three different radiation patterns (−8°, 0°, and +8°) at 35 GHz. The pattern analysis was based on the electric field vector addition method. The analytical, simulated, and measured results agree well with each other. Due to its compact and thin structure of 3.7 mm × 5.2 mm × 0.4 mm, this antenna can be applied in fields such as satellites, smartphones, etc.

Recently, a two-echelon city dispatching model with mobile satellites (2ECD-MS) has been proposed to reduce costs effectively. However, in addition to costs, speeds of delivery to customers are increasingly demanding in urban dispatching. This work extends 2ECD-MS to 2ECD-MS-CS by adopting the crowd-shipping model in the second-echelon dispatching, which uses occasional drivers of private vehicles to deliver parcels to improve the delivery speed. Furthermore, existing works generally consider the optimization from a single aspect, e.g., the delivery company. However, the sustainable development of a logistics company must also focus on other subjects in logistics activities, such as customers and delivery employees. So, we define a multi-objective model considering company cost, customer satisfaction, and income satisfaction of crowd-shippers simultaneously. The multi-objective optimization problem of 2ECD-MS-CS is solved by a multi-directional evolutionary algorithm (MDEA). In MDEA, multiple neighborhood operators are designed and combined with the multi-directional search strategy to fully explore the Pareto Front. Finally, we generate 40 new 2ECD-MS-CS instances based on existing common vehicle routing datasets. Experimental results show that 2ECD-MS-CS reduces the average cost by 3.4% and improves the delivery speed by 42% against 2ECD-MS in 40 instances with different customer scales, numbers of mobile satellites, and geographic scopes. The proposed MDEA outperforms several popular multi-objective optimization algorithms in both convergence and diversity. These illustrate the advantages of 2ECD-MS-CS especially in terms of delivery speed and the effectiveness of the proposed MDEA.

In this paper, a novel high isolation and high-capacitance-ratio radio-frequency micro-electromechanical systems (RF MEMS) switch working at Ka-band is designed, fabricated, measured and analyzed. The proposed RF MEMS switch mainly consists of a MEMS metallic beam, coplanar waveguide (CPW) transmission line, dielectric layer and metal–insulator–metal (MIM) fixed capacitors. The measured results indicate that the insertion loss is better than 0.5 dB at 32 GHz, and the isolation is more than 35 dB at the resonant frequency. From the fitted results, the capacitance ratio is 246.3. Compared with traditional MEMS capacitive switches, this proposed MEMS switch exhibits a high capacitance ratio and provides a wonderful solution for cutting-edge performance in 5G and other high-performance applications.

In this paper a high capacitance ratio and low actuation voltage RF MEMS switch is designed and fabricated for Ka band RF front-ends application. The metal-insulator-metal (MIM) capacitors is employed on a signal line to improve the capacitance ratio, which will not degrade the switch reliability. To reduce the actuation voltage, a low spring constant bending folding beam and bilateral drop-down electrodes are designed in the MEMS switch. The paper analyzes the switch pull-in model and deduces the elastic coefficient calculation equation, which is consistent with the simulation results. The measured results indicated that, for the proposed MEMS switch with a gap of 2 μm, the insertion loss is better than −0.5 dB and the isolation is more than −20 dB from 25 to 35 GHz with an actuation voltage of 15.8 V. From the fitted results, the up-state capacitance is 6.5 fF, down-state capacitance is 4.3 pF, and capacitance ratios is 162. Compared with traditional MEMS capacitive switches with dielectric material Si₃N₄, the proposed MEMS switch exhibits high on/off capacitance ratios of 162 and low actuation voltage.

In this paper, a novel ultra-wideband (UWB) printed antenna with quadruple band-notched characteristics is proposed and investigated. The quadruple band rejections are achieved by etching two interdigital capacitance slots on each side of the ground plane, embedding a curled C-shaped slot on the circle patch, and adding a curled split-ring resonator on the backside of the antenna. Interdigital inductance slots can obtain a narrower notched band than general structures due to their high inductance, thereby preserving some valuable frequencies. Adjusting the tail branch’s length and distance of the curled C-shaped slot and the curled split-ring resonator can control the notch frequency and width. Finally, the proposed antenna operates from 2.9–11 GHz (VSWR < 2) with four band stops (VSWR > 2) for rejecting WiMAX, WLAN, and downlink of X-band satellite communication. Furthermore, the difference between the experimental results and the expected value is less than 3%. The proposed antenna can accurately filter out narrow-band signals.