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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.

A ±45° polarization diversity dipoles’ antenna is designed and fabricated by 3-D printing technology in combination with mussel-inspired surface chemistry. For the fabrication of metal-coated 3-D antenna, mussel-inspired surface functionalization and electroless deposition technique were used for metallization of printed antennas. A dopamine-based coating layer was attached onto the printed antenna by heterogenetic-induced polymerization, to capture catalyst moieties for conducting electroless metal deposition on the surface and enabling the function of antenna. To prevent particle oxidation on the surface of copper, a method of antioxidation and anticorrosion protection for the copper layer is proposed without reducing the conductivity of antenna. In addition, a method based on surface treatment and rapid electrodeposition is proposed, which solves the problem of metal layer falling off in the traditional 3-D printing antenna structure. The 3-D printing antenna is measured, and the results show a good agreement with the simulated results. Both the simulated and measured results show that a port-to-port isolation >26 dB with VSWR 28 dB can be achieved for the proposed antenna. The 3-D printing antenna performances indicated that resin-based 3-D printing technology is promising in fabricating the antennas with lightweight and complex structures.

This paper demonstrates a 340-GHz band pass filter with a low insertion loss of ~-0.6 dB and a bandwidth of ~6%. This paper studies the relationship between filter diaphragm thickness and resonator length, and the quantitative relationship between insertion loss and fabrication tolerances. The diaphragm is quantitatively analyzed and the resonators lengths with correction factors are calculated for the accurate and robust filter parameters, and the simulation results based on calculated parameters show a robust filter structure as well as a good agreement with the theoretical analysis. The surface roughness and filter structure sizes deviation with different tolerances are studied and calculated for insertion loss. Finally, a filter with low insertion loss and good robustness is achieved by calculated parameters and a certain fabrication tolerance. Different fabrication precisions are carried out to verify the effect of size tolerances on the filter performance, including insertion loss and structural robustness. The filters, designed by the parameters analysis and fabricated by ≤ ~7.5-μm accuracy show good agreement between the simulation results and the test results, and when fabricated accuracy is ~5 μm, the insertion loss is ~-0.6 dB and the return loss is

This paper presents a novel miniaturization 90° phase shifter using parallel coupled inductors and capacitors. The size reduction is achieved by replacing the quarter-wavelength transmission lines in a conventional fixed 90 degrees phase shifter with the resonator circuit. The resonator circuit, formed by the parallel coupled inductors and capacitor, provides a 90° phase shift at 45 MHz. In this way, the circuit size can be largely reduced without sacrificing the operation bandwidth and power handling. The inductors structure used in the phase shifter carries high power, which consists of two full coupled rectangle metal coils. The proposed miniature fixed phase shifter is then applied to the design of a directional coupler centered at 45 MHz. The measured results show a bandwidth of 40–50 MHz for better than 35 dB return loss with a phase shift of ~ 90°, a deviation within ~ 2°, and power handling of 63 dBm (2 kW). Notably, the proposed fixed phase shifter occupies an area of 58.5 mm $\times30.5$ mm $\times33$ mm, which is only about $0.009\,\,\lambda _{\mathbf {0}}\times 0.0045\,\,\lambda _{\mathbf {0}}\times 0.005\,\,\lambda _{\mathbf {0}}$ at 45 MHz.

Objectives Spiral ganglion neurons (SGNs) include potential endogenous progenitor populations for the regeneration of the peripheral auditory system. However, whether these populations are present in adult mice is largely unknown. We examined the presence and characteristics of SGN-neural stem cells (NSCs) in mice as a function of age. Methods The expression of Nestin and Ki67 was examined in sequentially dissected cochlear modiolar tissues from mice of different ages (from postnatal day to 24 weeks) and the sphere-forming populations from the SGNs were isolated and differentiated into different cell types. Results There were significant decreases in Nestin and Ki67 double-positive mitotic progenitor cells in vivo with increasing mouse age. The SGNs formed spheres exhibiting self-renewing activity and multipotent capacity, which were seen in NSCs and were capable of differentiating into neuron and glial cell types. The SGN spheres derived from mice at an early age (postnatal day or 2 weeks) contained more mitotic stem cells than those from mice at a late age. Conclusion Our findings showed the presence of self-renewing and proliferative subtypes of SGN-NSCs which might serve as a promising source for the regeneration of auditory neurons even in adult mice.

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 awideband from4 to 9GHz, the filter is switched on and off to achieve the center frequency at ~7.81 and ~8.35 GHz separately. The filter is fabricatedon high-resistance silicon, 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 ( ${\textsf {f}}_{ { {{\textsf {0}}}}} \pm 0.5$ GHz), and the insertion loss is >−3.4 dB in the passband.

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.

In this paper, a non-planar conformal dual-polarized phased array antenna is proposed. The design of non-planar conformal antenna and optimized simulations are presented. The antenna design is based on a dual-polarized patch antenna element with vertical orthogonal baluns. The antenna element is backed by a compact cavity, to reduce the inter-element mutual coupling and to enhance the scanning performance of the curved conformal array. The proposed array achieves a wide fractional bandwidth of over 20%, when scanning up to ±45° in E and H planes. The validity of design is confirmed by simulation outcomes of 10 × 10 array model.

A conformal half-Yagi antenna is proposed in this work which can realize the directional pattern along the axial cylinder metal carrier. The antenna is designed based on the monopole antenna and traditional Yagi antenna. The proposed antenna is composed of an active monopole, one reflector pole and three director poles which are designed on the ground plane according to the operation frequency range. The proposed antenna achieves a wide bandwidth of over 20% from 14 GHz to 18 GHz which broken through the bandwidth limit of the traditional Yagi antenna. The design and optimization for the antenna was conducted in this work, and the simulated results of the maximum gain is about 8.7 dBi in the direction 25 degree offset from axial. And the gain is about 5 dBi in the axial direction, the beam width is about 89 degree in the azimuth direction and about 32 degree in the elevation direction. The S 11 is less than −15 dB in the frequency range of 14 GHz to 18 GHz. The prototype of the antenna is fabricated by the NC milling process on a whole aluminum plate which can obtain the good mechanical strength performance. The measured results of the S 11 and the gain can agree with the simulated results. The dimension of the prototype antenna is about 50 mm × 30 mm × 10 mm, and the height of the prototype antenna protruding the surface of the conformal carrier is only about 5 mm. And the weight of the prototype antenna is about 14.8 g which is suitable for installing on the platform of conformal cylinder metal carrier which required the light weight for microwave communication.

This paper presents a novel J band (220&ndash, 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 &lt, ~4 dB from 220 GHz to 270 GHz in the &ldquo, UP&rdquo, state, and isolation of ~16 dB from 220 GHz to 320 GHz in the &ldquo, DOWN&rdquo, state. Such switch shows great potential in the integration for terahertz components.

This paper presents a novel planar phased array that can work in Ka band designed for two-dimensional scanning. A four-modes pattern reconfigurable element based on microstrip Yagi antenna is proposed, and then developed into the 4X4 phased array, in which two feed points are introduced to reduce sidelobe level (SLL). The simulated results show that our proposed phased array is able to cover the scanning range from -60{\deg} to +60{\deg}in H-plane(yoz-plane) and -47.2{\deg}to +47.2{\deg}in E-plane(xoz-plane) with the gain reduction less than 3dB, both the SLLs of which are 10dB less than main beam. The two-dimensional scanning phased array based on pattern reconfigurable antenna (PRA) presented here is suitable for the satellite communication., Comment: 4 pages, 6 figures

A novel localization technique of printed chipless RFID in 3-D space is presented by using a frequency domain chipless tag. The chipless tag is interrogated by an ultra-wideband (UWB) signal, and the response from tag is analyzed for extracting the resonance information. The range information is used for accurate localization of chipless tag. The validity and accuracy of the localization method has been verified by moving the tag to different points in a fixed interrogation zone. The measured angular deviations achieved based on the proposed approach are less than 5 $^{\circ}$ when localization radius is from 10 cm to 40 cm.

This paper presents an analytical solution for capacitance and characteristic impedance of CPW with defected structures (CPW DS) in signal line. The first category of incomplete elliptic integrals F (φ, k) is employed for calculation, and the capacitance and characteristic impedance of CPW GS in signal line are first time achieved by the analytical solution. FEM simulation results are used to verify the results of analytical solution, which shows a good agreement. All calculations are completed in software Wolfram Mathematica, and CPW structures are simulated in software HFSS.

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 (er=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.

The terahertz wave source plays an important role in high rate indoor communication. There are two techniques to radiate the terahertz wave, electronic and photonic techniques. According to the environment of terahertz indoor wireless communication, some good choices of THz source devices are proposed, such as mixer, resonant tunneling oscillator and THz-over-Fiber technique. The latest research results of our work are given in detail.

A novel band-pass filter using a dual-mode resonator is presented with a excellent performance. The effect of out/input coupling structures arranged at 1800 geometrically is discussed for the dual-mode filter. The coupling coefficient between degenerate modes of dual-mode resonator is investigated by the perturbation size. The dual-mode band-pass filter is designed, fabricated and measured. The filter is designed and implemented at 2.8 GHz with 10.5% bandwidth, and the performances show a low passband insertion loss of 0.7 dB with good harmonics inhibited and the rejection better than 25 dB from about 3 GHz.

A C-band 2×2 microstrip quasi-Yagi antenna array has been designed to meet the requirement of small volume and light weight antenna of a C-band microwave communication system. The simulation and optimization for the antenna unit were conducted and the structure parameters were extracted. The fabrication and test for the 1×2 microstrip quasi-Yagi antenna array were implemented on the bases of simulation. The results of simulation and test can coincide with each other, and the return loss is less than −10 dB in the range of 4 to 5 GHz. The simulation for the 2×2 antenna array has been carried out basing on the test of 1 ×2 antenna array, and the simulated gain of the antenna array is more than 13 dB, the return loss is less than −10 dB in the frequency range of requirement.

There is an increasing demand for flexible electronics and optoelectronic devices, which requires designing and developing electronic devices on flexible substrates. Realization of flexible electronics with comparable or equal performance to conventional silicon-based microelectronics could enable a significant amount of new applications. Digital printing technologies have achieved great success on depositing functional materials to form patterns on flexible substrate, which is essential for flexible electronics development. In this review, we first summrize the unique advantage of digital printing technology over conventional microelectronics and other non-digital based printing methods, like screen printing. Then this article reviews the research and development of digital printing technology for fabriction electronic devices on flexible substrates. Firstly, the printing materials, including conductive materials, semiconductor materials and insulatiing materials, are throughly discussed and different flexible substrates are also reviewed. Then, from reviewing different digital printing techniques, the challenges of implementing flexible electronics into practical application are discussed. Three typical digital printing techniques are discussed, including inkjet printing, electrohydrodynamic printing and aerosol jet printing. Both the limitation and the advantage of digital printing techniques are discussed. One of the major advantages of digital printing is their ability of incorporating the processes into R2R manufacturing process, which is critial for both industry and consumer products, and eliminates the limitation of prototyping application. Thirdly, the related applications of digital printing on the flexible electronic devices are shown. In this review, the key technologies and application of flexible electronics are analyzed, different materials and digital printing technologies, and their applications in 2D/3D printed electronics are shown. Although flexible electronics has achieved great success, the challenges still remain. At the end, some opinions about the development of flexible electronics are raised. The flexiblity, functionality and durablity of flexible electronics still need to be improved in order to provide more practical products into the market.