Pyramidal Log-Periodic Dipole Array for Constant Phase Center
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Solution Overview
Problem
Existing broadband antennas face limitations in maintaining constant beam width, directivity, and phase center location over a large frequency band, often resulting in reduced performance due to frequency-dependent phase center movement and complex mechanical solutions.
Innovation Solution
A broadband multi-dipole antenna design featuring a pair of parallel dipoles with coinciding geometrical centers, arranged in a pyramidal geometry, and fed using various techniques to maintain rotationally symmetric radiation patterns and constant phase center across several octaves of bandwidth, while being lightweight and cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If logperiodic antennas are arranged in pyramidal geometry to achieve broadband radiation, then bandwidth is improved, but phase centre location becomes frequency-dependent causing directivity reduction
Solution Approach 1:
The antenna is divided into four identical logperiodic dipole antennas arranged in a pyramidal geometry, with each antenna operating at different frequency ranges. This segmentation allows the system to achieve broadband radiation while maintaining stable phase centre location through the combined radiation patterns of all segments.
Solution Approach 2:
The four logperiodic antennas are positioned asymmetrically in a pyramidal configuration with specific spacing and orientation. This asymmetric arrangement, combined with appropriate phase shifting, creates a radiation pattern with stable phase centre location across the broadband frequency range, resolving the frequency-dependency issue.
2Reliability
If corrugated horn antennas are used to feed reflectors, then rotationally symmetric radiation pattern and low cross polarization are achieved, but manufacturing cost and weight increase
Solution Approach 1:
The patent replaces expensive corrugated horn antennas with logperiodic dipole antennas that are cheaper to manufacture. The logperiodic structure uses simple conducting elements arranged in a periodic pattern, eliminating the need for complex corrugated waveguide structures while maintaining broadband performance.
Solution Approach 2:
Instead of using a single wideband feed antenna with complex structure, the invention inverts the approach by using multiple narrowband logperiodic antennas working together in a pyramidal array. This distributed approach achieves the same broadband performance with simpler, lighter individual elements.
3Stability of the object's composition
If multiple dipole pairs are arranged to achieve constant beam width, then beam width stability is improved, but device complexity increases
Solution Approach 1:
Each logperiodic dipole antenna in the pyramidal array serves multiple functions: it contributes to broadband radiation, maintains rotationally symmetric beam pattern, and helps stabilize the phase centre location. This multi-functionality is achieved through the symmetric pyramidal arrangement and identical design of all four antennas.
Solution Approach 2:
The four logperiodic antennas are arranged in a nested pyramidal configuration where smaller antennas are positioned inside the structure formed by larger antennas. This nested arrangement allows compact packaging while maintaining the radiation characteristics of individual elements, reducing overall system complexity.
Data Source
AI summary
The invention describes a broadband multi-dipole antenna that has low input reflection coefficient, low cross polarization, rotationally symmetric beam and constant beam width and phase center location over several octaves bandwidth. The dipoles are fed from one or a few feed points, and they may with advantage have log-periodic dimensions. The antenna is more compact, has lighter weight and is cheaper to manufacture than other solutions. It is very well suited for feeding single, dual or multi-reflector antennas.