Dipole Antenna Capacitive Coupling Layout for Array Return Loss
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Solution Overview
Problem
Dipole antenna elements with parasitic elements exhibit less than desired return loss characteristics when placed in an array antenna, causing interference and degradation in signal patterns and return loss of mid or high band signals.
Innovation Solution
A capacitive coupling arrangement with a conductive strip on a PCB, positioned in parallel with the dipole arm, forms a capacitive coupling element with a low cross-sectional area, reducing parasitic effects on higher band elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a parasitic element is added to increase bandwidth, then the frequency bandwidth of the dipole antenna is increased, but the return loss characteristics deteriorate when placed in an array antenna
Solution Approach 1:
The patent reorients the capacitive coupling element from a horizontal configuration (parallel to the reflector) to a vertical configuration (perpendicular to the reflector). This dimensional change reduces the cross-sectional area of the parasitic element as viewed from above, thereby minimizing interference with mid and high band elements in the array while maintaining the bandwidth enhancement function.
2Adaptability or versatility
If a parasitic element is positioned horizontally parallel to the reflector, then the capacitive coupling is effective for bandwidth increase, but the cross-sectional area increases causing interference to higher band signals
Solution Approach 1:
The capacitive coupling element is reoriented from horizontal to vertical positioning. This changes the dimension in which the cross-sectional area is measured, reducing it from a large horizontal footprint to a minimal vertical profile when viewed from above, thus eliminating interference with higher band elements.
Solution Approach 2:
The patent changes the orientation parameter of the capacitive coupling element from horizontal (parallel to reflector) to vertical (perpendicular to reflector). This parameter change fundamentally alters the spatial footprint of the element, reducing its cross-sectional area while preserving its capacitive coupling function.
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 achieves broad bandwidth return loss in the low frequency range while minimizing impact on the return loss of smaller mid or high band elements, maintaining symmetry and optimal performance.
Implementation Method 1
A capacitive coupling arrangement with a conductive strip on a PCB, positioned in parallel with the dipole arm, forms a capacitive coupling element
Data Source
AI summary
In a dipole antenna, a capacitive coupling element is introduced in the form of a conductive strip and is placed in parallel with the dipole conductive strip of the dipole arm. To that end, the conductive strip of the capacitive element is formed on a first copper layer of the PCB in parallel to an extended conductive strip of a dipole arm, that is also disposed on the first copper layer of the PCB. The conductive strip of the capacitive element extends horizontally from the center of the dipole arm in an equal distant on each side. A capacitive plate is placed on the second copper layer of the PCB on the opposite side of the first copper layer and is coupled to the conductive strip of the capacitive element via a plated through hole. The capacitive plate placed on the second copper layer extends downwardly so that a portion of it overlaps with the dipole conductive strip located on the first copper layer forming the capacitance coupling element.