Patch Antenna Array With Passive Radiators for Cross-Polar Isolation
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Solution Overview
Problem
Existing antenna systems face challenges in achieving high cross-polar isolation and beam shape control, particularly in cellular wireless networks with frequency reuse factor of 1, where signals from adjacent sectors interfere due to orthogonal polarizations.
Innovation Solution
An antenna array assembly with a ground plate and elongate passive radiators having alternating ridges and grooves in a zigzag arrangement, electrically isolated from the ground plate, to regenerate co-polarized fields and reduce cross-polar interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single linear array of patch antennas is used as a sector antenna, then the device complexity is reduced, but the gain flatness within the sector and the rate of cut-off outside the sector are limited
Solution Approach 1:
The antenna array is segmented into multiple patch elements arranged in a linear array, with each patch contributing to the overall beam pattern. This segmentation allows control over the radiation pattern while maintaining a relatively simple structure compared to more complex antenna designs.
Solution Approach 2:
The patent introduces a second dimension by adding passive radiators that extend perpendicular to the plane of the patch elements. This creates a three-dimensional antenna structure that improves gain flatness and cut-off rate without significantly increasing the complexity of individual elements.
2Manufacturing precision
If passive radiators are used to modify beam shape, then the beam shape control is improved, but unwanted coupling between signals for nominally orthogonal polarisations occurs
Solution Approach 1:
The passive radiators are designed with specific local geometries including ridges and grooves that are optimized for their particular function. The ridges are oriented to interact with one polarization while the grooves interact with the orthogonal polarization, creating local quality variations that reduce cross-polar coupling while maintaining beam shape control.
Solution Approach 2:
The patent converts the potentially harmful cross-polar coupling into a beneficial effect by using the passive radiators with ridge-groove structures. The coupling that would normally be unwanted is instead utilized to improve cross-polar isolation through careful geometric design, where the ridges and grooves create differential interactions with orthogonal polarizations.
3Productivity
If adjacent sectors are operated using the same frequency band, then the frequency utilization is improved, but signals from adjacent sectors appear as interference
Solution Approach 1:
The antenna design incorporates preliminary beam shaping through the linear array configuration and passive radiator structures. This preliminary action creates a focused main beam with controlled side lobes before signals are transmitted, reducing the likelihood of adjacent sector interference from the outset and enabling frequency reuse.
Solution Approach 2:
The patent maintains continuous useful action by ensuring that the antenna radiation pattern provides consistent coverage within the sector while rapidly attenuating signals outside the sector boundaries. This continuous beam pattern with sharp cut-off enables uninterrupted service within the sector and minimizes interference to adjacent sectors using the same frequency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances cross-polar isolation and beam shape control, providing a flat gain within the sector and fast cutoff outside, reducing interference and increasing capacity in cellular systems.
Implementation Method 1
at least some of the conductive parts of a respective elongate passive radiator are disposed in an arrangement having parallel ridges and grooves, in which, in a cross section in a plane parallel to the first face of the ground plate, the ridges extend towards the linear array and the grooves extend away from the linear array
Implementation Method 2
the arrangement of parallel ridges and grooves increases isolation between signals transmitted and/or received by the patch radiator elements for a first and second polarisation
Data Source
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AI summary
An antenna array assembly comprises a ground plate (1, 14), a linear array of patch radiator elements (12a-12d, 11a-11d) disposed in a spaced parallel relationship with a first face of the ground plate, and a first and second elongate passive radiator (4, 5) each comprising a plurality of conductive parts (22a-22c, 23a-23c) each disposed to be generally upstanding in relation to the first face of the ground plate and being electrically isolated from the ground plate. The first and second elongate passive radiators (4, 5) are disposed symmetrically on either side of the linear array and parallel to a centre line of the linear array, on the same side of the ground plate as the linear array. At least some of the conductive parts of a respective elongate passive radiator are disposed in an arrangement having parallel ridges and grooves, in which, in a cross section in a plane parallel to the first face of the ground plate, the ridges extend towards the linear array and the grooves extend away from the linear array.