Longyue Qu

A neutralization‐line (NL) decoupling method with a dipole‐patch‐antenna (DPA)‐oriented design rule is proposed for high‐density arrays. The NLs are directly connected between adjacent patches near their open ends, where the voltage is maximum, and the current is minimum. An equivalent‐circuit model and parametric analysis demonstrate that the connection position and NL impedance jointly control the compensating coupling. The design rule is validated in dual‐, tri‐, and twelve‐element MIMO configurations as well as 1‐D and 2‐D linear arrays. A fabricated twelve‐element prototype achieves a 200 MHz impedance bandwidth from 3.4 to 3.6 GHz, isolation exceeding 16 dB, a measured peak broadside gain of 6.3 dBi, and far‐field envelope correlation coefficients below 0.1. These results demonstrate the method's applicability to high‐density multi‐element DPA arrays.

In this paper, a MIMO antenna system was designed using two antennas operating in different modes: a ground-radiating antenna based on a half-wavelength structure and a dipole antenna based on a one-wavelength configuration. Due to the distinct operating modes of the two antennas, intrinsic decoupling between the elements is achieved without the need for additional isolation structures. The measured impedance bandwidths of the designed MIMO antenna are 310 MHz and 450 MHz for each element, respectively. The isolation between the two antennas was observed to be below –12 dB across the entire operating bands, and a maximum isolation of –20.2 dB was recorded at the null point. Furthermore, due to the radiation pattern diversity of the two antennas, the envelope correlation coefficient (ECC) remains below 0.1 throughout the bands, indicating excellent diversity performance. These characteristics make the proposed MIMO antenna a strong candidate for 5G applications requiring high isolation and low correlation.

This work presents an ultra-compact and lightweight ceramic-free dual-band GNSS antenna based on a characteristic-mode-guided distributed capacitive loading technique with an air-dielectric structure, where antenna miniaturization and performance enhancement are achieved through distributed capacitive loading and multi-path current excitation, respectively. Dual-band CP operation at the GNSS L5 and L1 bands is realized using a compact dual-feed stacked configuration. The fabricated antenna occupies a volume of 24 × 24 × 9 $mm^{3}$. Measured results show -10 dB impedance bandwidths of 1.2% and 1.9%, 3-dB axial-ratio bandwidths of 0.5% and 0.6%, and peak gains of 0.6 dBic and 2.9 dBic, confirming its suitability for compact GNSS applications.

This letter presents a wideband, high-gain, circularly polarized dielectric lens antenna with high aperture efficiency, featuring a dual-function triangular polarizer that enables circular polarization(CP) and enhances aperture efficiency. Lenses with uniform material are compared, with the plane-convex design selected for integration. The antenna achieves a peak gain of 29.1 dBic and maximum aperture efficiency of 72%, with S11 < -10 dB from 23.8 to 40 GHz. From 22.5 to 35 GHz, aperture efficiency exceeds 50% and axial ratio remains below 3 dB, demonstrating wideband performance. By minimizing insertion loss, optimizing aperture utilization and achieving CP, this design is ideal for 5G and beyond wireless systems.

This communication presents a novel dual-mode decoupler (DMD) that integrates orthogonal J-mode and M-mode within a single planar structure, enabling simultaneous suppression of E-plane and H-plane coupling in compact patch antenna arrays. Analytical modeling, based on a four-port impedance network, clarifies the operation mechanism, showing how mode-specific impedance loading achieves robust decoupling. Experimental results demonstrate the DMD’s versatility: J-mode or M-mode can be selectively employed for independent E-plane or H-plane decoupling, while synergistic operation supports dual-polarized MIMO, 2D 4 × 4 MIMO, and same-sense circularly-polarized (CP) MIMO designs. Simulations and measurements confirm the CP MIMO implementation achieves a 5.1 dBi peak gain and a 180 MHz axial ratio bandwidth (3.6% at 5 GHz). The DMD mitigates E-plane and/or H-plane coupling in dense arrangements, improving scalability and multi-polarization performance for wireless systems.

This paper introduces a dual-band co-polarized MIMO patch antenna utilizing a charge redistribution stub (CRS) technique to achieve high port-to-port isolation within a shared-aperture design. The proposed approach leverages I-shaped CRS (I-CRS) and L-shaped CRS (L-CRS) to independently control modal resonance and field redistribution, achieving high isolation and broadside radiation across two frequency bands. First, theoretical isolation conditions are derived, demonstrating that equal-magnitude, antiphase mode pairs are required for effective decoupling. Metallic vias are then employed to establish a TM21-TM22 mode pair for isolation in the higher band, while I-CRS and L-CRS structures are introduced to form a TM01-TM04 mode pair and correct radiation patterns, ensuring dual-band functionality with co-polarization. A prototype was designed, fabricated, and tested, showing excellent performance with isolation exceeding 20dB, impedance bandwidths of 3.0% and 9.2%, and peak gains of 7.6 dBi and 9.3dBi across the two bands. The measured envelope correlation coefficient (ECC) values remain below 0.1, confirming strong MIMO diversity performance. Therefore, the proposed MIMO antenna achieves dual-band operation in a shared aperture configuration through a charge redistribution mechanism, while maintaining high port-to-port isolation and demonstrating stable broadside radiation characteristics with low cross-polarization levels, making it a strong candidate for next-generation wireless systems.

In this letter, we construct a novel compact multi-resonance antenna structure using the ground radiation technique to achieve the intended target frequencies of 2.4–2.5 GHz and (5.125–7.125 GHz) the Wi-Fi 6/6E dual-band. According to the measurement results, under a 3:1 voltage standing wave ratio, the proposed antenna achieved a bandwidth of 450 MHz (ranging from 2.20 GHz to 2.65 GHz) in the lower band, maintaining an average total efficiency of 60.7% from 2.4 GHz to 2.5 GHz. Furthermore, a bandwidth of 2,640 MHz (ranging from 4.81 GHz to 7.45 GHz) was achieved in the higher band, with the average total efficiency being 53.4% from 5.0 GHz to 7.125 GHz. The measured antenna radiation pattern also showed satisfactory antenna radiation performance. Overall, the proposed antenna displays strong potential for use in mobile communication applications.

This letter presents a compact six-port MIMO antenna system with three antenna modules, each arranged in divergent directions for optimal spatial reuse, polarization diversity, and isolation enhancement. Decoupling components are incorporated to achieve shared-aperture decoupling. Measured results show isolation exceeding 11.5 dB between ports, a −6 dB bandwidth covering 3.4–3.6 GHz, and radiation efficiency above 50% per port. The proposed design improves spatial reuse and integration for mobile applications, making it a promising solution for next-generation MIMO communications.

This letter introduces a novel dual-band decoupling concept using capacitor-loaded shorting posts (CLSPs) as modal tuners to align the resonances of TM₀₂ and TM₁₂ with TM₀₁ and TM₁₁, respectively. Leveraging modal superposition of two pairs of anti-phase current modes, a dual-band, dual-port single-patch antenna is developed, operating in the 3.5 GHz and 5.5 GHz frequency bands. Measurements confirm the design's effectiveness, improving the isolation from 3.5 dBi to over 12 dB, with peak gains of 6.5 dBi and 7.1 dBi in the respective bands.

This study proposes a novel receiving antenna with higher upper hemisphere efficiency for global navigation satellite systems (GNSS) applications. The proposed novel and new-loop-type antenna consists of a series capacitor for input impedance adjustment and two shunt capacitors for resonant frequency control. The proposed method is based on the excitation of the horizontal mode of the ground plane to improve the upper hemisphere efficiency, thus achieving high-reception performance such as good signal-to-noise ratio and upper hemisphere isotropic sensitivity. The proposed antenna was verified in both simulation and measurement, and a 1.5 dB higher upper hemisphere gain was obtained in measurement than that achieved by a conventional inverted-F antenna in the global positioning system (GPS) L1 band (1,575 MHz).