This paper presents a compact topology for implementing Multiband bandpass Filters. The design uses interconnected multimode resonators (MMRs) and multi-level impedance structures to achieve a specific frequency response. This approach simplifies the design of quadruple bandpass Filters for 4G and 5G applications. Since line widths cannot be adjusted post-construction, resonance positions require tuning. To evaluate the Filter design process, a prototype incorporating MMRs was designed, manufactured, and analyzed, demonstrating close alignment between analytical predictions and experimental measurements, despite no simulation or optimization being performed during the design phase, except for result verification.Additionally, a design criterion is established to facilitate the rapid and reliable synthesis of Multiband responses by varying only a few geometrical parameters of the MMRs. A simulation of this structure was conducted using CST software to confirm the proposed theory's accuracy. A reverse-biased varactor diode, which functions as a capacitor with specific admittance, is utilized to provide the necessary tuning capability. The paper also highlights the impact of the varactor diode's admittance on resonance location adjustments. To validate the design, the authors present a fabricated prototype of the proposed Filter, which features quarter bands at 1.8, 2.1, 2.7, and 3.4 GHz, achieving an attenuations greater than -15 dB. The quarter band Filter is primarily used in wireless telecommunications networks. Due to their specialized design, these Filters can process multiple frequency bands simultaneously, enhancing communication quality and increasing network capacity in crowded and interference-prone environments.

This paper presents a new approach for the design of a Multiband uniplanar CPW-fed monopole antenna. The antenna consists of a fork like monopole strip to which is added an inverted U-shaped strip. The three branch fork like strip can create three resonant bands within the WLAN range while the placement of the inverted U-shaped strip provides a better impedance matching for the lowest resonant frequency band. Loading slot on the top of the U-shaped strip with asymmetric arms can add two further resonant frequency bands. This antenna can cover the frequencies of PCS, WiMAX and WLAN applications along with the major part of the C band. A prototype of the antenna is fabricated and tested. A good agreement is found between simulated and measured results.

As an important control element in steam heating piping systems, the safety and stability of inverted bucket steam valves determine the reliable operation of the system. Therefore, it is necessary to investigate the acoustic mechanism of inverted bucket steam valves. Aiming at the difficulty of numerical simulation in accurately predicting the aerodynamic noise of inverted bucket steam valves, this paper proposes a new method for simulating the aerodynamic noise of inverted bucket steam valves based on Multiband analysis (LES). The flow field of the inverted bucket steam valve is numerically simulated using the LES method to obtain wall pressure pulsation information and fluid velocity pulsation information, which are used as excitation sources for acoustic simulation. The characteristics of dipole and quadrupole sound sources were obtained by applying the FW-H method and experimentally verified. The results show that a new multifrequency band analysis method for inverted bucket steam valves is effective by comparing the numerical simulation results, in which the dipole source dominates in the low-frequency band, in the medium frequency range, the quadrupole source outperforms the dipole source, but in the high frequency range, the quadrupole source is dominant. The experimental results are in good agreement with the simulation results, and the correctness of the numerical simulation is confirmed by the fact that there is less than a 3% difference between the findings of the numerical simulation and the experimental data.

In this paper, a novel planar hybrid Multiband antenna formed by a loop-type antenna, a monopole slot antenna, and a coupled planar monopole antenna for the mobile phone is proposed. The loop-type antenna comprises a driven monopole and a coupled strip that printed on the other side of the substrate and short-circuited to the ground. The 0.5l and 1.0l mode of the loop-type antenna are excited. Therefore, the 0.5l mode of the loop-type antenna forms a wide bandwidth of 326 MHz to cover the GSM850/900 operation and the 0.25l mode of the monopole slot antenna, the 1.0l mode of the loop-type antenna, and the 0.25l mode of the coupled monopole antenna provide a wide bandwidth of 1181 MHz to cover the GPS/DCS/PCS/UMTS/WLAN2.4/WiMAX operation. Finally, the 0.5l mode of the coupled monopole antenna forms a wide bandwidth to cover the WLAN5.2 operation. Moreover, the hybrid antenna occupies a compact area of 16.5´45 mm2 and it has good radiation characteristics over the operating bands.