Dielectrically Loaded Multifilar Antenna Gain Beamwidth Trade-off
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Solution Overview
Problem
Existing dielectrically loaded antennas face challenges in achieving an improved gain-times-bandwidth product, particularly at frequencies above 200 MHz, with limitations in beamwidth and efficiency for circularly polarized radiation.
Innovation Solution
A dielectrically loaded multifilar antenna with a solid core of high relative dielectric constant, featuring multiple pairs of helical antenna elements and a common interconnecting conductor, optimized for circularly polarized radiation, achieving a zenith gain of +3 dB relative to isotropic and maintaining a wide beamwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the relative dielectric constant of the core material is increased to improve antenna gain, then the gain increases, but the beamwidth decreases
Solution Approach 1:
The patent applies parameter changes by selecting a core material with a specific relative dielectric constant range (10-21, preferably 16-19) to optimize the balance between gain and beamwidth. This parameter optimization allows the antenna to achieve +3 dB gain while maintaining at least 90° beamwidth for circularly polarized radiation.
Solution Approach 2:
The patent transitions from conventional two-dimensional planar antenna elements to three-dimensional helical antenna elements that wrap around the cylindrical core. This dimensional change enables the antenna to achieve enhanced gain through the helical path while maintaining wide beamwidth through the three-dimensional radiation pattern.
2Device complexity
If the antenna element structure is simplified to reduce device complexity, then manufacturing becomes easier, but the gain-times-bandwidth product decreases
Solution Approach 1:
The patent segments the antenna into four distinct helical elements arranged symmetrically around the core, each contributing to the overall radiation pattern. This segmentation allows for simplified individual element design while achieving high gain-times-bandwidth product through collective operation and circular polarization.
Solution Approach 2:
The patent merges multiple helical antenna elements into a single integrated structure around the core, combining their radiating capabilities to achieve enhanced gain-times-bandwidth product. The common support structure and coordinated arrangement of elements create a unified antenna system that outperforms simpler configurations.
3Device complexity
If conventional dielectrically loaded antennas are used, then the structure is simpler, but the efficiency for circularly polarized radiation is reduced
Solution Approach 1:
The patent employs a composite structure combining a dielectric core material with relative dielectric constant 10-21 and four helical conducting elements. This composite configuration optimizes energy efficiency for circularly polarized radiation by combining the dielectric's field confinement properties with the helical elements' polarization capabilities.
Solution Approach 2:
The patent uses helical (curved) antenna elements instead of straight or planar elements. The helical curvature is essential for generating circularly polarized radiation with high efficiency, as the rotating current path along the helix naturally produces the required polarization mode with minimal energy loss.
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 antenna achieves enhanced gain and efficiency for circularly polarized radiation with minimal reduction in beamwidth, suitable for applications like satellite radiotelephones, by utilizing a high dielectric constant core and specific antenna element configurations.
Implementation Method 1
an electrically insulative core of a solid material which has a relative dielectric constant of at least 10
Implementation Method 2
a three-dimensional antenna element structure on or adjacent the core outer surface which comprises at least two pairs of substantially helical conductive antenna elements
Data Source
AI summary
A dielectrically loaded multifilar antenna has an electrically insulative solid core bearing an antenna element structure having four pairs of substantially helical radiating elements spaced apart around a central axis of the antenna. Each pair of oppositely located antenna elements forms part of a conductive loop having an effective electrical length in the region of N guide wavelengths at the operating frequency, where N is an integer and is at least 2. Typically, each helical element executes substantially a full turn around the axis on the outer surface of the core. The antenna offers an improved gain-bandwidth product compared with typical prior dielectrically loaded multifilar helical antennas, and a 3 dB beamwidth of at least 90° for circularly polarized radiation.