Antenna Array Excitation Weighting for Low Signal Correlation
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Solution Overview
Problem
Existing antenna arrangements in MIMO and diversity applications face challenges with high signal correlation and reduced field strength in the side-lobe region, leading to inadequate coverage and performance, especially for mobile terminals close to the base-station.
Innovation Solution
The antenna arrangement employs two sets of excitation weights with differing magnitude and delay weights for each radiating element, positioning roots off the Schelkunoff unit circle to create radiation patterns with low correlation and null-fill differences in the side-lobe region, ensuring the main beam directions coincide and providing improved coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If identical excitation weights are used for corresponding radiating elements in multiple antenna arrays, then the radiation patterns are consistent and easy to control, but the signal correlation between arrays remains high in the side-lobe region
Solution Approach 1:
The patent applies different excitation weights to corresponding radiating elements in different antenna arrays. Specifically, while magnitude weights remain identical, phase weights are made different for at least some corresponding elements. This creates local variations in the radiation patterns' phase characteristics, which reduces signal correlation in the side-lobe region while maintaining overall pattern control.
2Device complexity
If antenna arrays are closely spaced or co-located to reduce hardware complexity, then device complexity decreases, but signal correlation increases in the side-lobe region
Solution Approach 1:
The patent changes the phase weight parameters for corresponding radiating elements in different antenna arrays. By adjusting these phase parameters, the radiation patterns are modified such that their phase relationships differ, thereby reducing signal correlation even when arrays are closely spaced or co-located. This allows compact configurations without sacrificing reliability.
3Reliability
If different excitation weights are applied to reduce signal correlation, then signal correlation decreases, but the radiation patterns become more complex to design and implement
Solution Approach 1:
The patent applies different excitation weights selectively rather than uniformly across all elements. Specifically, magnitude weights remain identical for corresponding elements, while only phase weights are differentiated. This localized differentiation reduces signal correlation while minimizing the complexity increase, as the magnitude structure remains simple and predictable.
4Device complexity
If traditional antenna arrays are used without null-filling, then the radiation pattern structure is simple, but field strength is reduced in null regions leading to poor coverage
Solution Approach 1:
The patent pre-calculates and pre-configures excitation weights that account for null-filling requirements. By designing the excitation weight sets in advance to produce radiation patterns with filled nulls, the system ensures improved coverage in regions where traditional arrays would have weak field strength, without requiring real-time adjustments or complex adaptive structures.
Data Source
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AI summary
An antenna arrangement comprising at least two antenna arrays (M, M', M"), each array comprising a plurality (N) of radiating elements (R) being arranged so as to have at least a plurality of corresponding radiating element positions, wherein for each radiating element there is associated an excitation means (E) comprising a magnitude weight (A) and a delay weight (a), wherein there is a first set (SE) of excitation means (E) associated with a first array (M) providing a first radiation pattern and a second set (SE') of excitation means (E) associated with a second array (M') providing a second radiation pattern. At least two respective excitation means (E) associated with a corresponding radiating element position of at least two respective arrays (M, M', M") have at least two different magnitude weights (An, A'n, A"n), and at least two respective excitation means (E) associated with a corresponding radiating element position of at least two respective arrays (M, M', M") have at least two different delay weights (an, a'n, a"n). The excitation weights (An, A'n, A"n; an, a'n, a"n) of the at least first and second sets of excitation means (SE, SE') are selected so that the main beam directions of the at least two antenna arrays essentially coincide and so that at least the magnitude of the correlation coefficient (p) associated with respective signals (S, S') communicated over the at least first and second array (M, M', M") is below 0.7 in a given side-lobe region, or so that the radiation amplitude patterns (P, P') associated with the at least first and second set of excitation means have an envelope with a substantial null-fill difference in a given side-lobe region with regard to the main beam peak.