PCB Antenna with 3D Conductive Jacket for Loss Reduction
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Solution Overview
Problem
Miniaturization of planar antennas on circuit boards leads to high current flow at edges, resulting in high losses due to high field strengths in the circuit board material, which existing technologies have not effectively addressed.
Innovation Solution
Designing a circuit board antenna with two congruent conductor tracks on an insulating layer, forming a closed rectangular jacket of electrically conductive material around a core, allowing current to spread throughout and minimizing losses by using standard PCB manufacturing steps, such as through-holes and slots, and incorporating a capacitive or inductive trimmer for precise tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If planar antennas are miniaturized on circuit boards, then the antenna size is reduced, but the losses increase due to high field strengths in the circuit board material
Solution Approach 1:
The patent transitions from a two-dimensional planar antenna design to a three-dimensional structure by adding conductive layers on the side surfaces of the circuit board through through-holes. This vertical dimension allows current to flow through multiple layers, increasing the effective conductor cross-section and reducing current density, thereby reducing ohmic losses while maintaining miniaturization.
Solution Approach 2:
The antenna structure combines multiple materials: the circuit board substrate, conductor tracks on the top and bottom surfaces, and conductive plating in the through-holes. This composite structure creates a multi-layer conductive path that distributes current more effectively, reducing the high field strengths and associated losses that occur in single-layer miniaturized antennas.
2Device complexity
If current flows only at the edges of conductor tracks, then the antenna structure is simple, but the losses increase due to high field strengths in the circuit board material
Solution Approach 1:
The antenna conductor is segmented into multiple discrete conductive elements: top surface conductor tracks, bottom surface conductor tracks, and through-hole conductive plating. These segments are electrically connected to form a distributed current path that spreads current throughout the entire antenna structure, reducing current density and ohmic losses while maintaining structural simplicity.
Solution Approach 2:
The conductive elements are nested within each other in a hierarchical manner: conductor tracks are placed on the top and bottom surfaces, and through-holes with conductive plating connect these surface layers. This nested arrangement creates a compact, multi-layer conductive structure that maximizes current distribution within a small volume, reducing losses without increasing overall complexity.
3Ease of manufacture
If the insulating layer is continuous, then the manufacturing process is simple, but the electric field cannot emerge into loss-free space
Solution Approach 1:
The patent extracts or removes portions of the insulating layer at strategic locations, specifically at the edges of the radiator where the conductive layers are positioned. This creates gaps or openings that allow the electric field to emerge from between the conductive layers into the surrounding air or vacuum, which has negligible dielectric losses compared to the circuit board material.
Solution Approach 2:
The gaps in the insulating layer act as intermediaries that facilitate the transition of the electric field from the lossy dielectric environment of the circuit board to the loss-free environment of the surrounding space. By removing the insulating material at critical points, the electric field can propagate through air rather than being confined to and attenuated by the lossy dielectric.
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
This design reduces attenuation and allows for precise tuning of the antenna, minimizing ohmic losses and optimizing the conductor shape for high frequencies, while maintaining a compact structure with low mechanical and electrical losses.
Implementation Method 1
Due to the current displacement effect at high frequencies, the penetration depth in the electrically conductive material is also small, so that the layer thickness of the conductor tracks and the conductive layers on the sides already represent an optimal conductor shape
Implementation Method 2
Since the insulating layer of the circuit board is separated along the edges of the radiator between the ends of the radiator, the electric field of the radiator can emerge into a space in which there is no lossy dielectric in the form of the insulating material, at least in the immediate vicinity
Implementation Method 3
a capacitive or inductive trimmer can be arranged between the radiator and a conductor arranged on the assembly surface of the circuit board
Implementation Method 4
a capacitive or inductive trimmer can be arranged between the radiator and a conductor arranged on the assembly surface of the circuit board
Data Source
Figure 1~2
Figure 3~6
Figure 7~8
AI summary
A printed circuit board (PCB) comprising a component placement area and a PCB antenna is described. The PCB antenna includes a radiator (14) consisting of two congruent conductive traces (22, 24) on opposite sides of an insulating layer on a PCB (12) coated with a conductive material on both sides. The insulating layer is coated at the edges of the radiator (14) with an additional conductive layer (26, 28). All conductive layers (22, 24, 26, 28) are electrically connected such that a cross-section through the radiator (14) forms a closed rectangular shell of electrically conductive material around a rectangular core of insulating material. A gap (38) is located between at least one edge of the radiator (14) that borders the component placement area.At the beginning (16) and at the end (18) of the emitter (14) the further conductive layer (26, 28) is interrupted by bores (44) or millings with a clear width larger than a gap (38) created by the separated and removed insulating layer of the circuit board (12).