Phased Array Blade Antenna Assembly for Airborne Lateral Coverage
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Solution Overview
Problem
Airborne antennas, especially those operating in lower frequency bands, suffer from suboptimal pattern coverage and reduced Effective Radiated Power (ERP) due to interaction with aircraft structures, leading to antenna pattern distortion and impedance variations.
Innovation Solution
A two-element phased array blade antenna assembly with a 180-degree hybrid divider/combiner and semi-rigid RF cables, featuring sub-resonant choke baluns for impedance matching, providing a 50 ohm nominal input impedance and eliminating the need for additional impedance matching networks, resulting in improved lateral coverage and EM interference suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional airborne antennas are used at lower frequencies, then the antenna can operate in the desired frequency range, but the antenna pattern becomes distorted and impedance varies adversely due to interaction with aircraft structure
Solution Approach 1:
The antenna is divided into multiple blade elements arranged in a phased array configuration. Each blade element is a dipole structure that can be independently controlled, allowing the overall antenna pattern to be synthesized through phase and amplitude control of individual elements. This segmentation enables the antenna to achieve desired radiation patterns despite proximity to aircraft structure.
Solution Approach 2:
The blade elements are positioned and oriented with specific local characteristics to optimize their interaction with the aircraft structure. The phased array configuration allows different local radiation patterns to be combined to achieve a desired overall pattern that minimizes distortion from nearby structures.
2Power
If conventional airborne antennas are used at lower frequencies, then the antenna can transmit RF signals, but the Effective Radiated Power is reduced due to strong interaction with aircraft wings or fuselage
Solution Approach 1:
The phased array configuration enables dynamic control of the radiation pattern through electronic phase and amplitude control of individual blade elements. This allows the antenna to adaptively steer beams and shape patterns to maximize Effective Radiated Power in desired directions while minimizing interaction with aircraft structure.
Solution Approach 2:
By changing the phase and amplitude parameters of signals fed to individual blade elements, the antenna can optimize its radiation characteristics. The sub-resonant choke baluns also transform impedance parameters to achieve better matching and reduce losses.
3Reliability
If impedance matching networks are added to the antenna system, then impedance matching performance improves, but device complexity and construction cost increase
Solution Approach 1:
The sub-resonant choke balun combines multiple functions into a single component: it transforms unbalanced coaxial cable signals to balanced dipole configurations, provides impedance transformation, and suppresses common-mode currents. This merging of functions eliminates the need for separate impedance matching networks while maintaining good impedance matching performance.
Solution Approach 2:
The choke balun structure uses the RF feed cable itself to create the impedance transformation and balancing effects through its sub-resonant design. The cable's own inductance and geometry are exploited to provide the matching function, eliminating the need for additional external matching components.
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 achieves increased effective radiated power, smooth lateral patterns, and reduced EM interference, while maintaining a lightweight construction and simplifying the antenna design, thereby enhancing operational effectiveness and reducing construction costs.
Implementation Method 1
The transformation of an unbalanced RF input coaxial cable to a balanced dipole configuration is accomplished with two sub-resonant choke baluns
Implementation Method 2
sub-resonant choke baluns
Implementation Method 3
Each antenna blade pair is coupled to a 180 degree hybrid divider/combiner by a semi-rigid Radio Frequency (RF) cable
Implementation Method 4
a two-element phased array blade antenna (PAB) assembly which provides improved lateral target coverage with an increased effective radiated power
Implementation Method 5
Each blade set is also connected to a sub-resonant choke balun 35 shown in FIG. 1 for improved impedance matching performance characteristics
Data Source
AI summary
An antenna design, having two symmetrical phased array blade antenna elements which provide improved lateral target coverage with an increased effective radiated power and exhibits smooth null-free bi-directional antenna patterns. Each blade antenna element is coupled to a 180 degrees hybrid divider/combiner by a semi-rigid RF cable. Each blade antenna element is also connected to a sub-resonant choke balun for improved impedance matching and resultant distortion-less antenna patterns.