Compact Box Dipole Radiator for Reduced Common Mode Radiation
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Solution Overview
Problem
Conventional box dipole radiating elements in base station antennas suffer from undesirable radiation patterns due to common mode currents, leading to narrowed azimuth Half Power Beam Width and rising 'shoulders' in the radiation pattern, which degrade overall antenna performance.
Innovation Solution
A compact box dipole radiating element with serpentine-shaped radiating arms and support stalks is designed to provide periodic paths for RF radiation currents, reducing common mode radiation and improving high-band cloaking characteristics, using stamped sheet metal or dual-sided printed circuit boards for construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional box dipole radiating elements are used with feed stalks at corners, then the antenna structure is simple and easy to manufacture, but common mode currents cause narrowed azimuth Half Power Beam Width and rising shoulders in the radiation pattern
Solution Approach 1:
The patent removes the traditional feed stalks from the corner positions of the box dipole radiating element. By extracting these problematic feed stalks that caused common mode currents, the radiation pattern issues (narrowed azimuth HPBW and rising shoulders) are eliminated while maintaining the overall box dipole structure for ease of manufacture
Solution Approach 2:
The patent introduces feed networks with impedance transforming sections as intermediaries between the feed points and the radiating elements. These intermediary components transform the impedance to prevent common mode currents while maintaining differential mode operation, thereby improving radiation pattern without complicating the basic box dipole structure
2Volume of moving object
If compact box dipole design is used to reduce antenna size, then the antenna becomes more compact, but common mode radiation degrades the radiation pattern
Solution Approach 1:
The patent converts the potentially harmful common mode currents into beneficial differential mode currents by using impedance transforming feed networks. The compact box dipole structure that would normally generate harmful common mode radiation is instead made to operate purely in differential mode, transforming a harmful effect into a beneficial one by controlling the current distribution through proper feed network design
3Device complexity
If feed stalks are used to mount dipole radiators, then the structure is simple and compact, but monopole radiation from non-excited stalks creates unwanted radiation patterns
Solution Approach 1:
The patent extracts and removes the feed stalks that were causing monopole radiation from the non-excited corners. By eliminating these stalks entirely, the unwanted monopole radiation is removed while the dipole radiators are mounted and fed through alternative feed network structures that do not generate harmful monopole patterns
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 enhances antenna performance by reducing unwanted radiation and maintaining electrical length, resulting in improved azimuth plane coverage and reduced radiation outside the main lobe.
Implementation Method 1
configured to provide periodic paths for RF radiation currents
Data Source
AI summary
A box dipole radiating element includes first, second, third and fourth pairs of support stalks, and a box-shaped radiator attached to the first through fourth pairs of support stalks. The box-shaped radiator has first through fourth sides including respective first through fourth radiating arms that are configured to provide generally serpentine-shaped paths for radiation currents in first through fourth vertical planes, which are aligned with the radiating arms and intersect at corners of the box-shaped radiator.