Compound GRIN Lens Antenna for High-Angle Scan Loss Reduction
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Solution Overview
Problem
Beam-scanning gradient-index (GRIN) lenses experience undesirable scan loss, particularly at high scan angles, due to the common switched-feed approach where feeds are uniformly oriented on a flat focal plane, leading to beam-widening, coma lobe, and reduced gain, exacerbated by spillover and aperture phase distortion.
Innovation Solution
A compound GRIN lens system incorporating an aperture lens and a focal lens (FCL) at each feed element, where the FCL is designed to squint the feed beam toward the center of the lens, reducing spillover and correcting aperture phase distortion, thereby improving beam collimation and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If feeds are uniformly oriented and placed on a flat focal plane, then the feeding scheme is simple and straightforward, but beam collimation deteriorates and spillover loss increases
Solution Approach 1:
The patent divides the single aperture lens into two separate lenses: an aperture lens and a focal lens. The focal lens is positioned adjacent to each feed element, while the aperture lens is positioned at the aperture. This segmentation allows each lens to perform a specific function—the focal lens corrects phase distortion and directs beams, while the aperture lens provides additional collimation—thereby reducing spillover loss and improving beam collimation without complicating the feeding scheme.
Solution Approach 2:
The focal lens acts as an intermediary element between the feed and the aperture lens. It receives radiation from the feed, corrects phase distortion, and directs the beam toward the aperture lens. This intermediary focal lens enables the simple flat-feeding scheme to achieve performance closer to that of a curved Petzval surface by mediating the transition from feed to aperture.
2Device complexity
If feeds are placed on a flat plane, then the structure is simpler, but aperture phase distortion increases and beam collimation worsens
Solution Approach 1:
The patent segments the collimation function into two separate lenses: the focal lens handles phase correction and beam direction, while the aperture lens provides final collimation. This segmentation allows the feeds to remain on a simple flat plane while achieving precise phase collimation through the combined action of the two lenses.
Solution Approach 2:
The focal lens performs preliminary phase correction and beam direction before the radiation reaches the aperture lens. By pre-correcting the phase distortion and directing the beams toward the aperture lens, the system achieves accurate beam collimation without requiring complex curved focal surfaces.
3Device complexity
If feeds are uniformly oriented on a flat focal plane, then the feeding arrangement is simpler, but beam scan performance deteriorates at high scan angles
Solution Approach 1:
The patent segments the beam forming function into two lenses, with the focal lens positioned adjacent to each feed element. This focal lens squints the beam toward the aperture lens and corrects phase distortion, enabling the simple uniform feed arrangement to maintain reliable beam scan performance even at high scan angles up to 50 degrees.
4Device complexity
If a single aperture lens is used with uniformly oriented feeds, then the system is simpler, but scan loss increases significantly at extreme scan angles
Solution Approach 1:
The patent divides the single aperture lens into two separate lenses: a focal lens positioned adjacent to each feed and an aperture lens positioned at the aperture. This segmentation reduces scan loss by having the focal lens pre-direct and phase-correct the beams, thereby minimizing spillover and improving energy efficiency at extreme scan angles.
Solution Approach 2:
The focal lens performs preliminary beam direction and phase correction before the radiation reaches the aperture lens. This preliminary action squints the beams toward the aperture lens and corrects phase distortion, significantly reducing scan loss at extreme scan angles while maintaining a relatively simple two-lens configuration.
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 compound GRIN lens system significantly reduces scan loss over extreme beam scan angles, maintaining high beam performance up to 50° with minimal loss, and enhances gain by reducing spillover and phase distortion, as demonstrated through full-wave electromagnetic simulations.
Implementation Method 1
an aperture lens disposed inside the channel near a second end thereof opposite to the first end, the aperture lens being configured to output collimated beams
Implementation Method 2
a first focal lens disposed inside the channel adjacent to an outlet of the first feed, the first focal lens being configured to squint a beam radiated from the first feed toward a center of the aperture lens
Data Source
AI summary
An electromagnetic antenna includes a channel configured to serve as a waveguide for electromagnetic radiation, a first and second feed disposed next to each other inside the channel at a first end thereof, the first and second feed being configured to radiate electromagnetic waves into the channel, an aperture lens disposed inside the channel near a second end thereof opposite to the first end, the aperture lens being configured to output collimated beams, a first focal lens disposed inside the channel adjacent to an outlet of the first feed, the first focal lens being configured to squint a beam radiated from the first feed toward a center of the aperture lens, and a second focal lens disposed inside the channel adjacent to an outlet of the second feed, the second focal lens being configured to squint a beam radiated from the second feed toward the center of the aperture lens.