Wideband decoupling technique for two‐element antenna array by using pixel neutralization line

Abstract

This letter proposes a high isolation two-element multiple input multiple output (MIMO) antenna by using a wideband pixel neutralization line (NL). The design procedures are simplified as follows: (1) Obtaining the Y-parameters of the original two-element antenna with a grid of microstrip stubs, and discrete ports are inserted among microstrip stubs; (2) obtaining the binary codes of the optimum route. Importing Y-parameters into MATLAB, and using a genetic algorithm to obtain the optimum connection route by design formulas upon scattering matrix which guarantees high isolation; (3) translating the binary codes into the actual connection metallic lines; (4) adding the designed pixel NL and appropriate matching branches into EM simulator to optimize the antenna; (5) obtaining a high isolation two-element antenna. The original two-element antenna has poor isolation with the main path coupling, and the pixel NL provides an auxiliary coupling path between two elements. By adjusting pixel NL, the magnitude strengths of two coupling signals realize the same, while the phases are exactly opposite. Therefore, the wideband high isolation between antenna elements is realized. To verify the practicability of the proposed pixel decoupling neutral line, a reference and proposed two-element MIMO antennas are fabricated and measured. In the experiment, the isolation of the proposed two-element antenna with an edgeto-edge distance of 0.0943λ 0 (λ 0 is the wavelength in free space at the center frequency) is enhanced by about 17 dB in the working frequency band from 0.975 to 1.025 GHz. Besides, an L-typed feeding network is added to guarantee a good matching condition. The proposed two-element antenna has a size of 0.617λ 0 × 0.667λ 0 , and the dimension of each radiation patch is 0.3267λ 0 × 0.0725λ 0 . The proposed GA algorithm-based decoupling technique has a significant superiority over traditional ones. Efficient, simple, and onetime EM simulation are its major advantages, which can liberate the RF engineer from the heavy debugging work.

Dual circularly polarized monostatic STAR antenna with enhanced isolation

“…Hence, our task is to focus on reducing the two more strongly coupled paths and , which come from the horizontal and vertical directions of the antenna, respectively. Considering that the volume of the MSTAR antenna cannot be increased, the planar EBG and DGS techniques are used to suppress the coupling between transmit and receive in the horizontal and vertical directions and have been extensively demonstrated in the literature (e.g., [21,22]).…”

“…Until now, there are many methods to improve the isolation of the antenna layer, including spatial multiplexing [12], polarization diversity [13][14][15] physical isolation [16], near-field cancellation [17,18], mode orthogonality [19,20], defected ground structure (DGS) [21], electromagnetic band gap (EBG) [22], neutral line [23], array layout [24], antenna decoupling surface [25], and so on. Several co-circular polarization (Co-CP) MSTAR antennas with identical right-handed circular polarization (RHCP) or left-handed circular polarization (LHCP) radiation for transmit and receive have been considered in the past [10,17,18,20,26].…”

Asymmetric PIFA antenna decoupling based on common and differential modes cancellation

“…Table 2 compares this work with the existing conventional decoupling schemes. Compared to the results of Cheng et al 3 and Li et al, 5 we have implemented a simpler decoupling scheme. Additionally, compared to the results of Sun et al 8 and Zhang et al, 9 we have further explored decoupling between asymmetric antennas that work in the same frequency band.…”

“…Therefore, reducing the coupling between antennas is one of the key problems to be solved to improve the performance of antenna arrays and MIMO systems. Various methods have been used to enhance the isolation between antennas, such as decoupling networks, 1 neutralization line methods, 2,3 electromagnetic band gaps, 4 defective ground structures, 5,6 and so on. Unfortunately, most of these decoupling methods have complex decoupling structures.…”

Single Layer Metamaterial Superstrate for Gain Enhancement of A Microstrip Antenna Array

“…Optimizing the configuration and arrangement of antenna elements within the array to achieve desired radiation patterns, beam steering capabilities, and side lobe suppression [9], utilizing multilayer stack configurations to add functionalities such as polarization diversity, frequency selectivity, and impedance matching [10,11]; mutual coupling often deteriorates an antenna array's radiation characteristics, to mitigate this, the element separation should be at least λ/2 (from center to center) to avoid mutual coupling and grating lobes [12], techniques to reduce mutual coupling include implementing electromagnetic band gap (EBG) structures [13], applying neutralization techniques [14], integrating stub transitions into the feeding microstrip line [15], etching slots or slits into the ground to create Defected Ground Structures (DGS) [16,17].…”