This article proposes a novel reconfigurable multimode microwave sensor integrating with resonance-and transmission-sensing capabilities for real-time noninvasive glucose monitoring. The sensor is initiated by utilizing a dynamic controllable spoof surface plasmon polariton (SSPP) transmission line (TL) and a multimode array resonator based on spoof localized surface plasmon (SLSP). This sensor possesses multiple resonance modes with high Q-factors, and its working characteristic can be flexibly manipulated by tuning the bias voltage applied to the loaded varactor diodes. Glucose monitoring is accomplished by analyzing the changes in the shift of multiple resonance frequencies and the amplitude of transmission coefficient within a specific operating band. Furthermore, an effective joint sensing method is developed by combining the results obtained from different resonance modes and various working characteristics of the sensor, which can greatly enhance sensitivity and the ability to correct errors. The experimental results demonstrate that, within a valuable glucose concentration range of 0–800 mg/dL, the presented sensor realizes a high sensitivity of 9.86 $\times$ 10 $^{\mathbf{-2}}$ MHz/(mg/dL) for resonance sensing and 2.00 $\times$ 10 $^{\mathbf{-2}}$ dB/(mg/dL) for transmission sensing. Also, the resonance sensing and transmission sensing exhibit an ultrahigh linear correlation, enabling the glucose sensor to possess robust crosschecking capability. Moreover, the results demonstrate that this sensor has a strong error correction function.

This letter proposes a novel simple planar circularly polarized (CP) frequency beam-scanning (FBS) antenna using slotline (SL) and spoof surface plasmon polariton (SSPP) structure. A new SL-SSPP slow-wave transmission line (TL) is initiated by periodically introducing orthogonal tilted corrugated grooves on both sides of the SL, which can generate orthogonal electric-field components in the same cross-section along the TL, and its dispersion characteristic can be flexibly adjusted. In order to excite an effective radiating mode from the propagating slow-wave mode, a simple double-sided tilted modulation method is devised to periodically modulate the SL-SSPP TL. Further, to obtain the CP characteristic, a π/2 phase displacement between the sinusoidal modulation structures on both sides of the TL is designed. The configuration of presented CP beam-scanning antenna owns the merits of simpler structure, low profile, and single dielectric layer. A prototype is manufactured and then tested to verify the proposed design. The experimental results con-firm that, within the 3-dB axial ratio (AR) bandwidth (from 7.2 to 8.35 GHz), the designed antenna achieves a 35° beam-steering range with CP characteristic. This antenna also realizes appropriate gain and radiation efficiency in the working band.

In this letter, a novel compact frequency beam-scanning antenna (FBSA) using composite waveguide based on folded half-mode substrate integrated waveguide (FHMSIW) and spoof surface plasmon polaritons (SSPP) is proposed. The novel composite FHMSIW/SSPP waveguide with compact size and high field-confinement is initiated by embedding dual SSPP structures into the FHMSIW. Its transmission characteristic has flexible features from both the FHMSIW and SSPP. To excite the radiation mode from the composite slow-wave waveguide, a simple single-sided sinusoidal modulation method is designed and used. In this way, the common open stop-band problem around broadside is effectively eliminated, and the beam-scanning range of the antenna can be flexibly designed without changing the modulation structure. The presented scanning antenna owns a compact size and a simple feeding network. The experimental results indicate that the proposed FBSA can achieve continuous beam scanning from backward to forward in a wide scanning range of 60° within a bandwidth of 7.7–10.1 GHz. The stable unidirectional radiation patterns and appropriate gains are also realized in the entire operating frequency band.

This paper proposes a novel dual-functional quasi-uniform beam-scanning antenna array (BSAA) with endfire radiation capability for integrated sensing and communication (ISAC) applications. A controllable quasi-uniform leaky-wave structure is developed by introducing subwavelength slots on both sides of the substrate integrated waveguide (SIW) and integrating tunable varactor diodes. This structure enables a dynamic fast-wave radiation mode within the targeted frequency range, allowing flexible dispersion control. By leveraging the fast-wave nature of the excited mode and tuning the varactor capacitance, the proposed BSAA realizes both frequency-scanning (FS) and fixed-frequency electronic-scanning (ES) functionalities, both supporting endfire radiation. The BSAA is designed by integrating two pairs of mirror-symmetric leaky-wave antenna elements, with metallic vias incorporated to enhance impedance matching. Experimental results demonstrate that, with a capacitance setting of 0.8 pF, the array achieves continuous beam-scanning exceeding 50° per steerable beam as the frequency increases from 5.6 to 6.3 GHz. Furthermore, at a fixed frequency of 5.9 GHz, the array achieves a beam-scanning range exceeding 65° per steerable beam by adjusting the varactor bias voltage from 1.1 to 7.5 V. This fixed-frequency ES functionality remains effective across multiple frequencies within the 5.6-6.3 GHz range, covering the dedicated short-range communication (DSRC) band for vehicle-to-infrastructure (V2I) applications. Moreover, the proposed BSAA achieves high gain performance in both FS and ES functions. These features position the proposed BSAA as a highly promising solution for various ISAC applications in intelligent transportation systems.

In this paper, a new printed triple-band planar antenna combing two different modified monopoles and an arc-shaped defected ground plane is proposed and studied. The used two simple monopoles consist of a rectangular ring and a rectangular patch attached a straight metal strip. And a compact arc-shaped defected ground structure is proposed and used to excite higher resonance frequency and improve the impedance matching of the antenna at lower and middle resonance frequencies. The main radiation element of the proposed antenna composed of only two simple monopoles can support three omnidirectional radiation modes at three desired bands. To indicate the working mechanism of the antenna, the design process is illustrated and the parametric studies are carried out. The experimental results of the fabricated prototype confirm that the triple-band antenna has better radiation efficiencies, appropriate gains, and stable omnidirectional radiation patterns. And the tested results also show that the antenna can provide enough bandwidths of 2.35–2.52, 3.2–4.16, and 5.13–5.87 GHz to cover all the desired 2.4/5.2/5.8 GHz WLAN and 3.5/5.5 GHz WiMAX operations. Moreover, the presented antenna has a very simple structure. Thus, the designed antenna has high practicality and broad prospects for WLAN and WiMAX applications.