Crossed-Dipole Antenna With Aperture-Coupled Feeding For High Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dual-linear polarized antennas face challenges in achieving high isolation between ports and maintaining polarization purity due to feedline parasitic interference and sensitivity to fabrication tolerances, leading to degraded cross-polarization levels and gain loss.
Innovation Solution
A dual-linear polarized crossed-dipole antenna design with bent dipole elements and a unique dual-polarized feeding structure, utilizing stripline feeding and symmetrical radiative elements, along with sub-ground planes and a principal ground plane to isolate radiative elements from baluns, achieving high port isolation and polarization purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If microstrip-fed or probe-fed antennas are used to achieve dual linear polarization, then the antenna structure is compact and easy to fabricate, but feedline parasitic interference degrades polarization purity and port isolation is limited to 30 dB
Solution Approach 1:
The patent introduces aperture-coupled feeding as an intermediary mechanism between the feedline and radiating elements. The feedlines are positioned on the opposite side of the substrate from the radiating elements, coupled through apertures in the ground plane. This intermediary coupling structure eliminates direct feedline-radiator interaction, thereby removing parasitic interference and achieving superior polarization purity while maintaining manufacturing simplicity
Solution Approach 2:
The patent transitions from planar co-located feeding to a three-dimensional aperture-coupled structure. Feedlines are placed on the bottom layer while radiating elements are on the top layer, separated by the substrate thickness. This dimensional separation in the vertical direction enables independent optimization of feeding and radiating structures, achieving both ease of fabrication and high polarization purity
2Reliability
If aperture-coupled antennas are used to achieve high port-to-port isolation of 35 dB, then isolation is improved, but antenna gain and simplicity are sacrificed and back lobe radiation increases
Solution Approach 1:
The patent optimizes multiple parameters including aperture size, aperture position, substrate thickness, and feedline dimensions to achieve the optimal balance between isolation and gain. By carefully tuning these parameters, the design achieves 35 dB isolation while maintaining high forward gain and suppressing back lobe radiation through proper aperture geometry and positioning
3Reliability
If non-planar cross dipole structures are used to achieve 34 dB port-to-port isolation, then isolation is improved, but the antenna becomes highly sensitive to fabrication tolerances and cross-polarization is severely degraded
Solution Approach 1:
The patent divides the antenna into functionally independent segments: feedlines on the bottom layer, ground plane with apertures in the middle, and radiating elements on the top layer. This segmentation allows each component to be optimized independently and reduces the cumulative impact of fabrication tolerances. The planar segmented structure is much less sensitive to manufacturing variations than non-planar integrated structures
Solution Approach 2:
The patent uses the vertical dimension to separate feeding and radiating functions, creating a planar multi-layer structure rather than a non-planar three-dimensional structure. This planar approach with vertical separation simplifies fabrication and reduces sensitivity to tolerances while maintaining the isolation benefits of aperture coupling
4Ease of manufacture
If printed dipole structures are used to achieve easy fabrication and 35 dB port-to-port isolation, then ease of manufacture is improved, but co- and cross-polarization peaks are collocated in the radiation pattern
Solution Approach 1:
The patent separates the feeding plane from the radiating plane by placing feedlines on the bottom substrate and radiating elements on the top substrate, with coupling through ground plane apertures. This vertical dimensional separation enables independent control of feed orientation and radiator orientation, allowing optimization of the radiation pattern to achieve separated co- and cross-polarization peaks while maintaining easy printed circuit fabrication
Data Source
AI summary
A dual linear polarized dipole antenna (and arrays of such antennas) having high isolation between ports. The antenna may include a pair of crossed (collocated) bent (angled) dipole antenna elements which are excited by a unique dual-polarized feeding structure. The antenna elements may be printed. Stripline feeding along with substantially symmetrical and substantially identical radiative (e.g., “radiating”) elements results in high level of port isolation. Sub-ground planes may be positioned about the stripline on both sides of a balun block to limit or reduce parasitic stripline radiation, thereby improving polarization purity. Polarization purity may be additionally reinforced by a principal ground plane which isolates the radiative elements from the baluns. The antennas and antenna arrays may be used, for example, for weather observation and air surveillance.