Spoof Surface Plasmon Research Articles

Linearly Scanning Spoof Surface Plasmon Polaritons Leaky-Wave Antenna With High Scanning Rate

Linearly Scanning Spoof Surface Plasmon Polaritons Leaky-Wave Antenna With High Scanning Rate

Spoof Surface Plasmon Polariton-Based Antenna and Array by Exciting Both Even- and Odd-Mode Resonances

Spoof Surface Plasmon Polariton-Based Antenna and Array by Exciting Both Even- and Odd-Mode Resonances

Compact bandpass filter with ultra-wide stopband based on spoof surface plasmon polaritons for sub-6G application

In this paper, a newly ring-shaped spoof surface plasmon polaritons (SSPPs) structure is proposed for the construction of bandpass filter (BPF) with combing the short-circuited stubs (SCSs). Compared with the conventional rectangular-shaped SSPPs unit, the proposed ring-shaped SSPPs unit has a relative lower cutoff frequency at the same periodic unit size. Moreover, the high-order modes of the ring-shaped SSPPs unit at different height are disperse distribution, which allows it to realize wide stopband suppression. The lower and upper cutoff frequencies of the passband can be respective controlled by structural parameters of SCSs and SSPPs unit. By properly adjusting the height of SSPPs units in conversion parts, a balanced performance between the passband and ultra-wide stopband suppression can be achieved. For verification, a BPF with the frequency from 2 GHz to 5 GHz for Sub-6G application and the stopband reaching 30 GHz is designed. The experimental show that the measured results agree well with the simulated results, validating the proposed structure and design method. The fabricated filter only occupies 1.13λg × 0.23λg, exhibits the advantage of compact size.

Wearable Full-Textile Spoof Surface Plasmon Polariton Transmission Line for Secured Communication in Wireless Body Area Network

Wearable Full-Textile Spoof Surface Plasmon Polariton Transmission Line for Secured Communication in Wireless Body Area Network

Efficient Amplification of Large‐Signal Spoof Surface Plasmon Polaritons in a Subwavelength Size

AbstractThe advancement of communication systems demands ever‐smaller sizes, leading to the integration of more circuits in compact forms. A promising solution lies in Spoof Surface Plasmon Polaritons (SSPPs), which enable strong confinement, low interference, and a significant wave vector, thereby facilitating smaller sizes. However, the amplification of large plasmonic signals in a compact size remains a daunting scientific challenge for the further development of SSPPs communication systems. In this study, this challenge is tackled by selecting GaN High Electron Mobility Transistors (HEMTs) and load/source‐pull technologies. To ensure efficient operation, impedance‐matching networks are designed, resulting in a remarkably small amplifier structure. The approach involves utilizing the Bayesian optimization (BO) algorithm to fine‐tune the matching network, leading to exceptional amplification performance. The results obtained in the frequency range of 1–3 GHz are highly promising, with both simulated and measured results demonstrating an impressive output power exceeding 40 dBm, a power added efficiency (PAE) surpassing 60%, and a gain exceeding 10 dB. These remarkable achievements underscore the viability of amplifying large‐signal SSPPs and outputting high‐power SSPPs waves within a subwavelength size, opening exciting possibilities for SSPPs communication, sensing, and imaging systems.

Demonstration of a terahertz coplanar-strip spoof-surface-plasmon-polariton low-pass filter

There is a growing interest in spoof surface plasmon polariton (SSPP) structures at terahertz (THz) frequencies for applications such as filtering, sensing, and communications. However, to date, there are limited experiments that confirm SSPP characteristics at THz frequencies. The majority of literature focuses on simulation or verification by device scaling to Gigahertz (GHz) frequencies where standard vector network analyzers are readily available. This paper presents the first experimental verification of SSPP characteristics at THz frequencies in a guided wave system using coplanar strip (CPS) feedlines. Specifically, we design three SSPP structures with varying band-edge frequencies (1.04 THz, 0.63 THz, and 0.53 THz), then fabricate and verify the low-pass transmission characteristics using a modified THz-time-domain spectrometer (THz-TDS) system. We find strong agreement between simulation, theory, and experiment.

Miniaturized electronically controlled notched band filter based on spoof surface plasmon polaritons

In this paper, a novel miniaturized electronical controlled notch band filter based on spoof surface plasmon polaritons (SSPPs) with inverted “山”-shaped unit is designed and experimentally demonstrated. The notch band filter is mainly composed of four parts: microstrip transmission line, transition structure, inverted “山”-shaped SSPPs, and split ring resonator (SRR) structure, and a varactor diode is embedded in the slit notch of the SRR structure to realize electronic control. Comparing with the traditional SSPP unit with the same lateral size, the dispersion curve of the proposed inverted “山”-shaped unit shows better slow wave characteristics, and the asymptotic frequency is reduced to 55%. The frequency of the notch band can be dynamically controlled by adjusting the external bias voltage at both ends of the varactor diode. As the external bias voltage increases from 0.5 V to 30 V, the notch band frequency can be changed from 2.1 GHz to 2.3 GHz and achieve easily electronic regulation. The simulation results show that the notched band filter achieves low insertion loss (<i>S</i><sub>21</sub> < –1 dB) and great return loss (<i>S</i><sub>11</sub> > –10 dB) in the pass band, which has the advantage of miniaturization with the size only 0.78<i>λ</i><sub>g</sub> × 0.35<i>λ</i><sub>g</sub>. It is worth noting that when the equivalent capacitance of the slit notch is changed, the transmission coefficient of the notched band is always less than –15 dB, showing superior band-stop performance. At the same time, by comparing and analyzing the electric field distribution of notch band filter, the transmission mechanism of microwave signal is further verified. In order to verify the its effectiveness, the traditional printed circuit board technology is used to fabricate notch band filter. The measurement results are in good agreement with the simulation ones, verifying the feasibility of the design. The electronically controlled notch band filter has higher integration and can effectively suppress the interference frequency band.

An externally perceivable smart leaky-wave antenna based on spoof surface plasmon polaritons

An externally perceivable smart leaky-wave antenna based on spoof surface plasmon polaritons

Compact Muti-Frequency Band-Pass Filters Based on High-Order Mode of Folded Line Spoof Surface Plasmon Polaritons Waveguide

Compact Muti-Frequency Band-Pass Filters Based on High-Order Mode of Folded Line Spoof Surface Plasmon Polaritons Waveguide

Spoof surface plasmon polaritons based detection of glucose in blood phantom for medical diagnosis

Spoof surface plasmon polaritons based detection of glucose in blood phantom for medical diagnosis

Kirigami-Triggered Spoof Plasmonic Interconnects for Radiofrequency Elastronics.

The flexible and conformal interconnects for electronic systems as a potential signal transmission device have great prospects in body-worn or wearable applications. High-efficiency wave propagation and conformal structure deformation around human body at radio communication are still confronted with huge challenges due to the lack of methods to control the wave propagation and achieve the deformable structure simultaneously. Here, inspired by the kirigami technology, a new paradigm to construct spoof plasmonic interconnects (SPIs) that support radiofrequency (RF) surface plasmonic transmission is proposed, together with high elasticity, strong robustness, and multifunction performance. Leveraging the strong field-confinement characteristic of spoof surface plasmons polaritons, the Type-I SPI opens its high-efficiency transmission band after stretching from a simply connected metallic surface. Meanwhile, the broadband transmission of the kirigami-based SPI exhibits strong robustness and excellent stability undergoing complex deformations, i.e., bending, twisting, and stretching. In addition, the prepared Type-II SPI consisting of 2 different subunit cells can achieve band-stop transmission characteristics, with its center frequency dynamically tunable by stretching the buckled structure. Experimental measurements verify the on-off switching performance in kirigami interconnects triggered by stretching. Overcoming the mechanical limitation of rigid structure with kirigami technology, the designer SPIs exhibit high stretchability through out-of-plane structure deformation. Such kirigami-based interconnects can improve the elastic functionality of wearable RF electronics and offer high compatibility to large body motion in future body network systems.

Multifunctional Spoof Plasmonic Transmission Line with Dynamically Switchable Modes

AbstractA multifunctional transmission line (TL) based on spoof surface plasmon polaritons (SSPPs) is proposed for dynamical switching features among bandpass, band‐stop, and dual‐band phase shifting functionalities. Different operating modes can be controlled in real‐time by changing the states of the Positive Intrinsic Negative (PIN) diodes synchronously. The dispersion properties of the spoof plasmonic unit cell and transmission characteristics of the tunable PIN‐diodes‐loaded spoof plasmonic TL are investigated to highlight the basic theory and method. A prototype of the proposed TL composed of five cascaded unit cells is fabricated and tested for proof‐of‐concept validation. In the ON state of the PIN diodes, the measured −3 dB transmission frequency bandwidth ranges from 3 to 8.1 GHz for the bandpass characteristic. In the OFF state, the measured −10 dB rejection band spans from 3.7 to 5.6 GHz for the bandstop characteristic. When the diodes are switched between ON and OFF states, the measured dual‐band phase shifts vary from 192° to 203° and 248° to 292° in the 3.1–3.4 GHz and 6.1–9.4 GHz frequency bands, respectively. The validated switchable features of the TL pave the way for applications of tunable SSPPs in large‐scale integrated circuits and smart wireless communication systems.

Balanced Filtering Power Divider based on Odd-mode Hybrid Microstrip and Slotline Spoof Surface Plasmon Polaritons

In this paper, an ultra-wideband balanced filtering power divider (B-FPD) with high common mode (CM) suppression level is proposed. The B-FPD is designed based on the odd mode spoof surface plasmon polaritons (SSPPs), which are constructed by the hybrid folded microstrip and slotline (HFMS) structure. Firstly, the dispersion characteristic and electric field distribution of the HFMS SSPP unit cell are investigated, which can decrease the upper cut-off frequency for size reduction of nearly 50%. Next, an equal balanced power divider with low cut-off frequency is proposed based on the microstrip-to-slotline transition structure and slotline Y-junction. Then, the balanced power divider is used to excite the odd mode of HFMS SSPP structure. An equal B-FPD with center frequency of 4.0 GHz is implemented, and the 3-dB bandwidth covers 0.9 to 7.0 GHz. Finally, the B-FPD with advantages of high CM suppression level and compact size is fabricated and measured.

Dual‐polarised end‐fire antenna based on the high‐order mode of spoof surface plasmon polaritons

AbstractA planar antenna with dual‐linearly polarised end‐fire radiation is proposed. A tapered double‐sided symmetrical spoof surface plasmon polariton (SSPP) transmission line (TL) with tilted unit cells is proposed. The SSPP TL can operate in two types of first high‐order modes: the first high‐order even mode and the first high‐order odd mode. A two‐port feeding structure is designed to feed the SSPP TL. When the signal is fed from port 1, the energy travels through the substrate integrated waveguide and eventually excites the even mode on the SSPP TL, leading to vertically polarised radiation. Conversely, when the signal is input from port 2, the energy travels through the stripline‐to‐slotline transition and eventually excites the odd mode on the SSPP TL, generating horizontally polarised radiation. According to the measured results, a 54.6% overlapping bandwidth is obtained. The horizontal and the vertical polarisations achieve a maximum gain of 14.7 and 12.2 dBi, respectively.

Single-Conductor Spoof Surface Plasmon Polaritons Transmission Line With Bandpass Feature Based on Embedded Cross-Shaped Resonators

In this brief, cross-shaped resonators (CSRs) are integrated in spoof surface plasmon polaritons (SSPPs) unit, and a novel compact single-conductor SSPPs transmission line (TL) with bandpass feature is proposed. In this design, a unit structure based on classical SSPPs structure embedded with a CSR is proposed. To analyze the proposed unit structure, scattering parameters and ABCD-matrix theories are used. After the theoretical analysis, a SSPPs TL with bandpass filtering property is designed. The simulated passband is from 7.9 to 12.2 GHz with a relative bandwidth of 42%. A prototype is fabricated and measured. The measured results are in agreement well with the simulated ones. This proposed structure is attractive and useful for the design of high integrated SSPPs circuits.

Terahertz plasmonic functional devices enabled by multimode interference

Terahertz integrated devices have attracted great attention due to their potential applications in communication systems. Although some functional devices based on terahertz spoof surface plasmon polariton (SPP) waveguides have been studied, multimode waveguides and multimode interference mechanism have rarely been explored. This work investigates several key functional plasmonic devices based on multi-SPP mode interference in the terahertz regime. The feasibility of multimode transmission on terahertz plasmonic waveguides and control of the propagation modes by varying the waveguide parameters are first investigated. Then, the interference mechanism between two or more propagation modes and the self-imaging principle are applied to plasmonic waveguides. Finally, a series of terahertz plasmonic functional devices such as a coupler, wavelength diplexers, and cascaded devices are proposed and simulated by exploring different interference lengths, frequencies, and cascades via the self-imaging principle. These devices have good performance in transmission response, crosstalk, bandwidth, and footprint, and are expected to play an important role in the development of terahertz on-chip communication systems.

A wideband and high-gain circularly polarized reconfigurable antenna array based on the solid-state plasma

In this paper, a wideband and high-gain circularly polarized (CP) antenna array with polarization-reconfigurable characteristics is presented based on the solid-state plasma (SSP). The proposed antenna is composed of switchable rotating radiation structures and a switchable feed network by simulating the different SSP branches. To investigate the CP operating mechanism, a reconfigurable CP element is designed through characteristic mode analysis (CMA). A switchable sequential-phase feed network is then proposed which can provide separately two rotational excitations. A spoof surface plasmon polariton (SSPP) is adopted for radiation patches to improve gain and axial ratio (AR) bandwidth. Finally, a high-gain and wideband 2 × 2 CP reconfigurable antenna array is designed. This array achieves left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) modes when different SSP branches are excited. The array has an overlapped impedance bandwidth of 61.9 % (3.17 to 6.01 GHz) and an overlapped AR bandwidth of 40.2 % (4.01 to 6.03 GHz) in two CP states, and the peak gain is 11.68 dBic.

Spoof surface plasmons based reconfigurable bandstop filter for THz applications

Spoof surface plasmons based reconfigurable bandstop filter for THz applications

Microwave absorption and compression performance design of continuous carbon fiber reinforced 3D printing pyramidal array sandwich structure

In this study, continuous carbon fiber reinforced 3D printing technology was used to create a novel pyramidal array sandwich structure (PASS), which contains microwave absorption and enhanced compression performances. By utilizing the electromagnetic and mechanical properties of continuous carbon fiber (CF), a spoof surface plasmon polaritons (SSPPs) microwave absorbing core was formed by winding continuous carbon fiber into a pyramidal array. Simulated and experimental results demonstrated that the proposed PASS efficiently absorbs a wide band (4–18 GHz) microwaves at large incident angles (0–60°), with an average absorptivity exceeding 90 %. Additionally, compression tests revealed that present continuous carbon fiber reinforced PASS has a compressive strength of 9.60 MPa and a modulus of 123 MPa, respectively. Furthermore, it exhibits 34.3 % and 24.8 % higher energy absorption per unit volume and mass compared to the pure polylactic acid (PLA) PASS. The advantages of microwave absorption, compression, and economical manufacturing performances make it highly promising for the engineering applications.

A novel sandwich structured spoof surface plasmon polaritons antenna integrating multibeam and enhanced mechanical performances

The conventional antennas will increase the radar cross section of aircrafts and affect their aerodynamic performances, a novel antenna scheme for radiation and load-bearing integrated design based on composite sandwich structure is proposed. By constructing spoof surface plasmon polaritons (SSPPs) structure and combining it with glass fiber composite (FR-4) plates, the radiation direction of the monopole can be controlled and the antenna will be endowed with load-bearing capacity. At the meantime, polymethacrylimide (PMI) foam is filled in its spacing to improve the mechanical performances greatly. Through electromagnetic (EM) simulation and test, it is found that four-beam radiation in different directions and eight-beam radiation can be realized by changing the position of the FR-4 laminates, and the bandwidth is all about 1 GHz with a peak gain about 6.5 dBi. Out-of-plane compression experiment indicates that the proposed PMI foam-filled multibeam antenna structure (PFMAS) gathers the high load-bearing capacity of multibeam antenna structure (MAS) and the high energy absorption characteristics of PMI foam, showing an obvious coupling effect. Its specific compressive strength is 150.10 % and 6.28 %, and energy absorption capacity per unit volume is 169.91 % and 362.08 % higher than that of PMI foam and MAS, respectively. The proposed PFMAS improves the structural utilization efficiency, and can be applied to some interlocking units of square honeycomb structure to endow multibeam radiation characteristics, which can expand the application of integrated antenna structures effectively.