Ring Focus Antenna Feed Design for Ultra-Wide Ku/Ka Bandwidth
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Solution Overview
Problem
Current satellite communication antenna systems face challenges in achieving ultra-wide bandwidth while maintaining high aperture efficiency and low side-lobe levels across various figures of merit such as aperture efficiency, side-lobe level, cross polarization discrimination, gain-over-noise temperature, effective isotropic radiated power, and voltage standing wave ratio, particularly for VSAT applications.
Innovation Solution
A ring focus antenna system with a splash plate feed assembly and a quad-ridged polarizing waveguide, featuring a parabolic main reflector, an elliptical sub-reflector, and a dielectric support with a shaped boundary, which includes a quad-ridged polarizing waveguide with varying ridge dimensions and a dielectric central portion, configured to provide ultra-wide bandwidth coverage for Ku-band and Ka-band frequencies, achieving an aperture efficiency greater than 70% and a side lobe level off peak gain of less than −20 dB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional parabolic reflector antenna is used, then the structure is simple, but the bandwidth is limited and aperture efficiency is insufficient
Solution Approach 1:
The antenna system is divided into multiple functional segments: a parabolic main reflector for broad bandwidth operation, an elliptical sub-reflector for focal point control, a splash plate feed assembly for signal distribution, and a quad-ridged waveguide for polarization management. This segmentation allows each component to be optimized independently while collectively achieving ultra-wide bandwidth with high aperture efficiency
Solution Approach 2:
The invention transitions from a conventional two-dimensional parabolic reflector to a three-dimensional ring focus configuration with an elliptical sub-reflector. This dimensional enhancement creates multiple focal points arranged in a ring pattern, enabling the antenna to maintain high gain and aperture efficiency across ultra-wide bandwidth by capturing and focusing EM energy from multiple spatial dimensions simultaneously
2Productivity
If the aperture efficiency is increased, then the gain is improved, but the side-lobe levels increase
Solution Approach 1:
The splash plate feed assembly implements local quality optimization by positioning multiple feed elements at specific locations around the ring focus. Each feed element is strategically placed to illuminate specific regions of the main reflector, creating localized constructive interference in the main beam direction while producing destructive interference in side-lobe regions. This selective illumination pattern achieves high aperture efficiency with suppressed side-lobes
Solution Approach 2:
The elliptical sub-reflector acts as an intermediary element between the central feed and the main parabolic reflector. It transforms the spherical wavefront from the feed into an elliptical wavefront that converges precisely onto the ring focus, enabling optimal illumination distribution across the main reflector aperture. This intermediary transformation ensures uniform energy distribution that maximizes aperture efficiency while minimizing side-lobe radiation
3Adaptability or versatility
If a single frequency band is targeted, then the antenna design is simplified, but the bandwidth coverage is limited
Solution Approach 1:
The antenna system achieves multi-functionality by designing the parabolic main reflector and elliptical sub-reflector geometry to support multiple frequency bands simultaneously. The ring focus configuration and splash plate feed assembly are engineered to maintain optimal performance across Ku-band (12-18 GHz) and Ka-band (26.5-40 GHz), allowing a single antenna structure to serve multiple satellite communication services without requiring separate antennas for each band
Solution Approach 2:
The invention utilizes parameter changes in the electromagnetic spectrum to achieve ultra-wide bandwidth. By carefully selecting and optimizing geometric parameters such as the parabolic reflector focal length, elliptical sub-reflector dimensions, and ring focus radius, the antenna maintains consistent performance characteristics across a wide frequency range. The design accommodates frequency variations by leveraging the inherent broadband properties of the parabolic-elliptical geometry combination
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 system effectively supports ultra-wide bandwidth satellite communication by enhancing aperture efficiency and reducing side-lobe levels, ensuring reliable signal transmission and reception across Ku-band and Ka-band frequencies, thereby meeting the stringent requirements of VSAT applications.
Implementation Method 1
The sub-reflector includes surfaces that include segments of an ellipse having a first focal point which coincides with an ISO phase center located inside the waveguide and a second focal point located on a ring focus of the main reflector
Implementation Method 2
the EM waveguide is a quad-ridged polarizing (QRP) waveguide having an ultra-wide bandwidth and a central axis
Data Source
AI summary
A ring focus antenna system has an ultra-wide bandwidth for receiving and transmitting electromagnetic (EM) signals. The system includes a main reflector having an axis of rotation and a splash plate feed assembly consisting of a waveguide and a sub-reflector which is substantially aligned with the axis of rotation. The sub-reflector has surfaces that include segments of a displaced ellipse, having a first focal point which coincides with an ISO phase center located inside the waveguide and a second focal point located on a ring focus of the main reflector. A dielectric support for the sub-reflector has a shaped boundary which eliminates refraction at the dielectric-air interface. In one embodiment, the ultra-wide bandwidth includes EM frequencies belonging to Ku-band and Ka-band communication frequencies. The waveguide may be configured as a quad-ridged polarizing waveguide.