PIFA Antenna Co-located with PCB Electronics Using Air Gap
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Solution Overview
Problem
Existing antenna designs face mechanical packaging challenges, leading to inefficiencies and increased costs due to the need for physical separation from conductive electronics, which results in larger sizes and higher costs, especially for frequencies below 2 GHz.
Innovation Solution
A planar inverted F antenna (PIFA) is implemented using a grounding plane in a printed circuit board and a metal chassis, with an air gap instead of dielectric material for separation, allowing the antenna and electronics to be co-located on the same board without reserved areas, using standoffs to short the grounding plane to the metal surface and a feed pin to connect to the metal chassis, reversing the conventional feed arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cable is used to space the antenna away from the chassis and electronics, then the antenna efficiency is improved, but the packaging size and cost increase
Solution Approach 1:
The patent merges the antenna structure directly with the PCB by forming conductive traces on the PCB layers, eliminating the need for separate cables and mounting structures. The top and bottom layers of the PCB are used to create the antenna elements, integrating the antenna function into the existing PCB structure without requiring additional packaging space.
Solution Approach 2:
The PCB serves multiple functions: it acts as both the circuit board for electronics and the structural framework for the antenna. The conductive traces on the PCB layers serve dual purposes as both electrical connections for electronics and radiating elements for the antenna, eliminating the need for dedicated antenna mounting structures.
2Reliability
If a reserved area on the PCB is used to isolate the antenna from electronics, then the antenna performance is improved, but the PCB size and cost increase
Solution Approach 1:
The antenna structure is merged with the PCB circuit traces, using the same conductive pathways for both electronics and antenna functions. The top layer conductive trace and bottom layer ground plane work together as antenna elements without requiring separate reserved areas, as the antenna current flows through the existing circuit traces.
Solution Approach 2:
The patent transitions from a planar 2D antenna design to a 3D folded structure by using both top and bottom layers of the PCB. The conductive trace is folded back underneath the PCB and connected to the ground plane on the bottom layer, creating a three-dimensional antenna structure that utilizes the vertical dimension of the PCB layers.
3Adaptability or versatility
If folded metal PIFA is used for lower frequency operation, then the frequency range is improved, but the antenna size and packaging cost increase
Solution Approach 1:
The patent changes the electrical parameters of the antenna by adjusting the trace width, trace length, and spacing between conductive elements on the PCB layers. By modifying these geometric parameters, the antenna can be tuned to operate at lower frequencies without requiring proportionally larger physical dimensions, as the effective electrical length is optimized through the folded configuration.
Solution Approach 2:
The antenna utilizes the third dimension by folding the conductive trace from the top layer down to the bottom layer of the PCB, creating a compact three-dimensional structure. This vertical folding allows the antenna to achieve the electrical length required for lower frequency operation while maintaining a compact footprint on the PCB.
4Ease of manufacture
If PCB-based PIFA is used with dielectric material separation, then the manufacturing ease is improved, but the antenna efficiency and bandwidth deteriorate
Solution Approach 1:
The patent extracts the dielectric separation material from between the antenna conductors and uses air as the separation medium instead. The top layer conductive trace and bottom layer ground plane are separated by air rather than being embedded in dielectric material, which eliminates the dielectric losses that would otherwise reduce antenna efficiency and bandwidth.
Solution Approach 2:
The PCB itself acts as a thin structural support element rather than a dielectric separator. The PCB provides mechanical support and positioning for the antenna elements while the actual electromagnetic separation is achieved through air, allowing the thin PCB structure to serve both mechanical and positioning functions without compromising antenna performance.
Data Source
AI summary
A PIFA is formed using a grounding plane in a printed circuit board and a metal chassis or shield. Rather than using the printed circuit board as the separator, an air gap or other gap than the printed circuit board is formed. The transmitter and/or receiver for the antenna may be mounted to the printed circuit board. The feed pin routes signals for the PIFA from the transmitter and/or receiver to the metal chassis or shield while being isolated from the grounding plane that acts as the radiating surface of the PIFA. Standoffs supporting the printed circuit board may be used to short, and another standoff may be used as the feed pin.