In-Plane Optical Feed for Phased Array Antennas
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional antenna arrays face challenges with balanced operation due to high input resistance at high frequencies, leading to performance restrictions such as limited bandwidth, operational frequency, weight, profile, and cost issues, particularly with the use of baluns and RF transmission lines.
Innovation Solution
An optically fed phased antenna array design that uses photodiodes and optical fibers to drive antennas, eliminating the need for baluns and RF transmission lines, with a conformal structure and reflectors to redirect optical signals, allowing for a low-profile, compact, and conformal configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional 50-Ω coaxial line feeding with baluns is used, then the antenna can operate at high frequencies, but the device complexity, weight, and profile increase due to additional transformers for each radiating element
Solution Approach 1:
The patent replaces the conventional electrical feeding system (coaxial lines, baluns, RF transmission lines) with an optical feeding system using optical fibers and photodiodes. This substitution eliminates the need for complex electrical transformers at each antenna element, significantly reducing device complexity and weight while maintaining high-frequency operation capability through optical signal transmission.
Solution Approach 2:
The invention extracts and removes the balun components from each antenna element by implementing a global optical feeding architecture. The optical fibers are routed through a common feed network that distributes optical signals to multiple photodiodes, each driving an antenna element without requiring individual baluns, thereby simplifying the overall system structure.
2Length of stationary object
If optical fibers are routed perpendicular to the antenna array plane, then the antenna array can have a low profile, but the installation complexity increases
Solution Approach 1:
The patent transitions the optical fiber routing from a perpendicular (vertical) dimension to an in-plane (horizontal) dimension. The optical fibers are routed within the plane of the antenna array substrate, following the contours of the array elements. This dimensional change maintains the low profile requirement while significantly simplifying installation, as the fibers can be easily laid out and connected within the planar structure without requiring precise vertical alignment through the array thickness.
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 optically fed antenna array achieves balanced operation without the need for baluns, reducing size, weight, and cost while maintaining high-frequency performance, enabling efficient signal transmission and conformal integration.
Implementation Method 1
Each optical fiber outputs its optical signal to a photodiode/antenna pair, where the photodiode receives the optical signal output from the optical fiber and outputs an electrical signal to drive the antenna to which it is connected.
Implementation Method 2
a plurality of reflectors, each positioned to be in optical communication with a corresponding one of the photodiodes; and a plurality of optical waveguides (e.g., optical fibers) extending in a direction conforming to at least one of the inner surfaces or outer surfaces of the antenna array substrate and the ground plane, each of the optical fibers connected to a corresponding reflector to provide a optical signal to a corresponding one of the photodiodes via the corresponding reflector.
Data Source
AI summary
A phased antenna array comprises a plurality of antennas and photodiodes arranged on a substrate. Each antenna is driven by an electrical signal output by the photodiode. The photodiodes each receive an optical signal via an optical fiber. The optical fibers conform to the sheet-like shape of the antenna array (which may be planar or curved) and optically communicate with a corresponding photodiode via a corresponding reflector, such as a ninety degree reflector. The reflectors may comprise a v-groove in a silicon substrate on which the optical fiber is positioned and a reflecting surface. Each reflector may be attached to the substrate or a ground plane positioned parallel to the substrate and the optical fiber may connect to the reflector in a direction running parallel to the phased antenna array. This optical feed network may accommodate tight spacing of the antenna elements (such as spacing less than 5 mm apart) with a thin profile.