Multiband Waveguide Feed Network Zero-Current Split

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Solution Overview

Problem

Existing antenna waveguide feed networks for wide bandwidths, such as the extended C-band, are complex and heavy, making them costly and difficult to manufacture, and traditional harmonic filters cannot be split on the zero-current region of the waveguide, leading to increased complexity and manufacturing risks.

Innovation Solution

A linear multiband waveguide feed network with inverse ridge harmonic lowpass filters and loaded split-block magic tees, which reduces complexity and manufacturing risk by positioning split-planes in low-risk zero-current regions, allowing for a three-part, direct-machined assembly that can be readily manufactured and scaled for various frequency bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional waveguide feed networks are used to cover wide bandwidths, then frequency coverage is improved, but device complexity and mass increase

Engineering Contradiction:

Improvefrequency coverageVSAvoidfeed network complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The waveguide feed network is divided into multiple sections separated by split-planes positioned at zero-current regions. Each section can be independently manufactured and then assembled, reducing the complexity of manufacturing the entire structure as a single piece while maintaining the required frequency coverage across extended C-band and other bands.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If traditional waveguide feed networks are used to cover wide bandwidths, then frequency coverage is improved, but mass increases

Engineering Contradiction:

Improvefrequency coverageVSAvoidfeed network mass

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

By segmenting the feed network into multiple sections that can be separately manufactured and assembled, the overall mass is reduced compared to a monolithic structure. The segmentation allows for optimized material usage and reduces the need for excessive structural support material.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses inverse ridge filters instead of traditional ridge filters. This inversion of the conventional filter design enables the filters to be positioned at zero-current regions where they can be effectively integrated into the segmented structure, reducing overall mass while maintaining filtering performance across wide frequency bands.

Inventive Principle:

Principle #13The other way round (Inversion)

3Object-generated harmful factors

If traditional ridge filters are used, then harmonic filtering is achieved, but manufacturing complexity increases due to inability to split at zero-current regions

Engineering Contradiction:

Improveharmonic interferenceVSAvoidmanufacturing complexity

Core Design Contradiction:

Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The patent inverts the conventional ridge filter design to create inverse ridge filters. This inversion allows the filters to be positioned at zero-current regions of the waveguide, which are ideal locations for split-planes. Consequently, the feed network can be manufactured in separate sections and assembled without compromising filter performance, significantly reducing manufacturing complexity while effectively suppressing harmonic interference.

Inventive Principle:

Principle #13The other way round (Inversion)

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 solution provides a high-performance, low-mass, and low-cost waveguide feed network that effectively isolates higher order modes and reduces manufacturing complexity, achieving significant mass and cost savings while maintaining high isolation and return loss specifications across extended frequency bands.

Implementation Method 1

inverse-ridge harmonic lowpass filters which offer isolation of higher order modes including TE20 in broad receive bands

Methodology Applied

Scientific EffectElectromagnetic wave propagation: Waveguide

Implementation Method 2

The first split-plane and the second split-plane are on the zero-current region of the device

Methodology Applied

Scientific EffectZero-current region electromagnetic property: Electromagnetic Induction

Data Source

PatentUS11177580B2Multiband linear waveguide feed network

Publication Date: 2021.11.16 LOCKHEED MARTIN CORP

AI summary

A linear multiband waveguide feed network device, which includes a first section, a second section, a third section and an inverse-ridge receive (Rx)-reject filter. The second section is coupled to the first section via a first split-plane. The third section is coupled to the second section via a second split-plane. The inverse-ridge Rx-reject filter is implemented as a first half-portion and a second half-portion. The first half-portion and the second half-portion are implemented in the second section and the third section, respectively. The first split-plane and the second split-plane are on a zero-current region of the device.