This letter demonstrates a terahertz (THz) bandpass filter with a center frequency of ~340 GHz, low insertion loss of ~ -0.6 dB, and bandwidth of ~5.3%. The diaphragm thickness is quantitatively analyzed to obtain accurate filter parameters based on equivalent circuit and diaphragm coupling in THz band for the first time, and the simulation results based on calculated filter parameters show that diaphragm thickness has great influence on the filter performance. The test results show a good agreement with the theoretical analysis and simulation results. Meanwhile, the relationship between fabrication error and insertion loss was discussed and a quantitative mathematical model is given. The filter also shows an excellent performance when compared with the performance of other filters from the current literature reports.

A switchable bandpass filter is presented in this paper, which is able to operate at two different frequencies. The “open-ring” resonators and cantilever microelectromechanical systems (MEMSs) switches are employed to form the switchable filter with a high rejection at out-of passband and a controlled dc bias of 26 V. A hybrid resonance circuit with both series circuit and parallel circuit are used as the equivalent circuit, which is used to accurately analyze the structure parameters. The MEMS switch capacitance, used for equivalent circuit and driving voltage estimation, is analyzed to achieve an exact predicted value by equivalent microstrip line model. The isolation of designed MEMS switch is greater than 40 dB with a wideband from 4 to 9 GHz, the filter is switched on and off to achieve the center frequency at ~7.81 and ~8.35 GHz separately. The filter is fabricated on high-resistancesilicon, and the measured results showed a good agreement with the simulated results. The filter performance shows a sharp rejection greater than 40dB at the frequency of (f ₀ ±0.5 GHz), and the insertion loss is >-3.4 dB in the passband.

This paper presents a coplanar waveguide (CPW) tunable band-stop filter using hybrid resonator and employing RF microelectromechanical systems (MEMS) capacitors. The MEMS switches are used as varactors to tune the filter resonance frequency. Defected ground structures (DGSs) with MEMS switch is employed for filter unit to achieve miniaturization of filter structure. To accurately analyze the filter unit structure parameters, a hybrid resonance circuit is used as equivalent circuit and the relationship of MEMS switch and the transverse slot capacitance is analyzed. Hereby, a CPW tunable band-stop filter, cascaded periodically by DGS and MEMS switches, is fabricated on a glass substrate (ε_r=3.78,tan δ = 0.0012). The filter has a midband retune loss of 2.3-2.8 dB and a tuning range of 35% from 8.5 to 12.3 GHz with a maximum dc voltage of 44 V. Finally, we propose a solution to achieve constant bandwidth when center frequency changes.

This paper demonstrates a packaged THz shunt capacitor micro-electromechanical systems (MEMS) switch with low insertion loss. In-line shunt switch is used to achieve a low loss in THz band, which is realized by reducing the equivalent parallel inductance of switch. The equivalent circuit of the switch is analyzed systematically, the equivalent resistance is obtained based on the skin effect of high frequency current on the conductor and the current density distribution characteristics of the conductor cross-section. The equivalent capacitance is obtained by using “double microstrip” characteristic impedance calculation method, and the correction factor ( $\Delta$ ) is introduced to calculate the equivalent inductance accurately. By optimizing equivalent circuit parameters and switch sizes, the structure of MEMS switch with low loss and high isolation characteristics are achieved. The switch is packaged by rectangular waveguide and achieved a low insertion loss. The comparison between the switch simulation results and the equivalent circuit simulation results verify that the parameter extraction method and circuit analysis are correct. The packaged MEMS switch is measured, and the results are in an acceptable agreement with simulation, the switch is actuated under voltage of ~30V. The measured result has achieved a low insertion loss with less than < 2dB from 220 to 280GHz, and isolation with ~16 dB from 240GHz to 320GHz in the “down” state.

This letter proposes an algorithm that combines the improved multi-objective beluga whale optimization (IMOBWO) algorithm with the iterative Fourier transform (IFT) technique to optimize the sidelobe level (SLL) and directivity of the phased array. The algorithm is derived from the traditional beluga whale optimization algorithm, based on the framework of multi-objective optimization. By improving the traditional algorithm and combining with IFT technology and oppositionbased learning strategy, the population diversity is enhanced, and the optimization ability of the algorithm is improved. By optimizing the array layout, the proposed method can effectively synthesize thinned planar phased arrays with low SLL and nondegraded directivity. Some specific examples are provided to confirm the effectiveness of the proposed method.

This paper presents a novel J band (220–325 GHz) MEMS switch design. The equivalent circuits, the major parameters, capacitance, inductance and resistance in the circuit were extracted and calculated quantitatively to carry out the radio frequency analysis. In addition, the mechanical property of the switch structure is analyzed, and the switching voltage is obtained. With the designed parameters, the MEMS switch is fabricated. The measurement results are in good agreement with simulation results, and the switch is actuated under a voltage of ~30 V. More importantly, the switch has achieved a low insertion loss of ~1.2 dB at 220 GHz and <~4 dB from 220 GHz to 270 GHz in the “UP” state, and isolation of ~16 dB from 220 GHz to 320 GHz in the “DOWN” state. Such switch shows great potential in the integration for terahertz components.