Oblique Radiating Elements for Omni-Directional Direction Finding
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Solution Overview
Problem
Existing direction finding antennas face challenges with complexity, limited bandwidth, large profile, and undesirable phase center layouts, which affect their performance in determining the angle of arrival of radiowave signals.
Innovation Solution
A modified log periodic antenna array with multiple radiating elements arranged at an oblique angle to the feedline, maintaining a phase center distance between 0.15λ and 0.2λ, which reduces directionality and profile while achieving omni-directionality and broad bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If dipole structures are used for interferometric direction finding antennas, then omni-directionality is achieved, but the profile becomes high (half wavelength) and bandwidth is limited
Solution Approach 1:
The antenna is divided into multiple discrete radiating elements (at least four elements) arranged in a specific geometric configuration. Each element contributes to the overall omnidirectional pattern while allowing the structure to achieve the desired half-power beamwidth without requiring a half-wavelength profile, thus resolving the contradiction between omnidirectionality and compact height.
Solution Approach 2:
The patent transitions from traditional planar dipole arrangements to a three-dimensional configuration where radiating elements are positioned at specific heights and angles. By introducing vertical spacing and oblique angles (25-65 degrees), the antenna achieves omnidirectional coverage and controlled beamwidth in the horizontal plane while maintaining a reduced vertical profile.
2Measurement precision
If multiple radiating elements are spaced for spatial separation at target wavelengths, then direction finding capability is improved, but the profile becomes large
Solution Approach 1:
Each radiating element is positioned with specific local characteristics including particular heights above the ground plane and oblique angles relative to the horizontal plane. This localized optimization of element positions and orientations enables the array to achieve the required spatial separation for accurate direction finding while keeping the overall profile compact through non-uniform vertical distribution of elements.
Solution Approach 2:
The radiating elements are arranged asymmetrically with respect to the ground plane, with each element tilted at a specific oblique angle between 25 and 65 degrees. This asymmetric configuration allows the antenna to achieve the necessary electrical spacing for direction finding accuracy without requiring proportional physical spacing that would increase the profile height.
3Power
If log periodic antenna with cardioid pattern is used, then directional tendencies are achieved, but omni-directionality is reduced and interference increases
Solution Approach 1:
The patent combines multiple radiating elements with identical or similar radiation patterns into an array configuration. By merging the fields from at least four elements positioned at specific locations and orientations, the system achieves omnidirectional coverage through constructive interference in all horizontal directions while the vertical spacing and ground plane create nulls in the vertical plane, eliminating the cardioid pattern's directional bias.
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
The solution provides a simple, omni-directional antenna system with a wide bandwidth of 1-3 GHz, a low profile, and optimal phase center layout, enhancing direction finding accuracy and reducing interference.
Implementation Method 1
Each radiating element is arranged at an oblique angle relative to an antenna axis and configured to radiate at a wavelength (λ)
Data Source
AI summary
Systems and apparatuses include a radio frequency feed configured to connect to a feedline, and a plurality of radiating elements coupled with the radio frequency feed. Each radiating element is arranged at an oblique angle relative to an antenna axis and configured to radiate at a wavelength (λ). The plurality of radiating elements define a phase center distance between about 0.15λ and about 0.2λ.