Dual End-Fed Leaky-Wave Antenna for Broadside Gain Recovery
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Solution Overview
Problem
Leaky-wave antennas suffer from significant gain loss at broadside frequencies due to the creation of standing waves within the leaky waveguide structures, limiting their effectiveness in applications requiring fixed broadside radiation patterns, such as 5G wireless communication systems.
Innovation Solution
A dual end-fed broadside leaky-wave antenna design utilizing perfect electrical conductor (PEC) and perfect magnetic conductor (PMC) integrated reflectors to excite leaky wave long slot arrays from both sides, achieving a broadside radiation pattern outside the open stopband region by ensuring the signals are anti-phase relative to each other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional single-end feeding is used for leaky-wave antennas, then the structure is simple, but gain loss occurs at broadside frequencies due to standing waves
Solution Approach 1:
The feeding system is segmented into two independent feeding paths, each with its own reflector (PEC and PMC), allowing separate control of signals fed to opposite ends of the leaky wave structure. This segmentation enables anti-phase excitation that eliminates standing waves at broadside frequencies while maintaining structural simplicity.
Solution Approach 2:
The invention uses anti-phase signals (180 degrees out of phase) from the two feeding paths to counteract the standing wave formation. The counter-propagating waves with opposite phases cancel each other's constructive interference, eliminating the gain loss at broadside frequencies.
2Shape
If periodic cell dimensions are increased to achieve narrow beam width, then beam width is reduced, but the structure requires 2D array configuration with power dividing circuits
Solution Approach 1:
Instead of increasing periodic cell dimensions in the transverse direction (which requires 2D arrays), the invention achieves narrow beam width by extending the leaky wave structure in the longitudinal direction and using dual-end feeding. This dimensional approach allows narrow beams without the complexity of power dividing circuits.
Solution Approach 2:
The invention inverts the conventional approach by feeding from both ends simultaneously with anti-phase signals, rather than using a single feed point. This inversion allows the structure to achieve narrow beam width through the interference pattern of counter-propagating waves without requiring complex power division networks.
3Reliability
If modified periodic cells are used to mitigate open stopband problem, then broadside radiation is enabled, but the antenna structure becomes complicated
Solution Approach 1:
The invention introduces PEC and PMC reflectors as intermediary elements that enable broadside radiation without modifying the periodic cells. The reflectors mediate the excitation process, creating the necessary anti-phase conditions at the ends of the leaky wave structure while keeping the periodic cell design simple and unchanged.
Solution Approach 2:
Instead of modifying the geometric parameters of periodic cells, the invention changes the excitation parameters by using anti-phase signals from dual-end feeding. This parameter change in the feeding approach enables broadside radiation capability while maintaining the simplicity of the original periodic cell structure.
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
This design enables high gain directive beams over a bandwidth without the need for complicated feeding networks, allowing the antenna to radiate effectively at broadside frequencies and maintain performance across various frequency bands.
Implementation Method 1
the first part includes an approximately perfect electrical conductor (PEC) reflector. The first part is configured to direct a first signal to or from the first end of the leaky wave structure
Implementation Method 2
the second signal being an anti-phase (e.g. approximately or exactly 180 degrees out of phase) version of the first signal... enabling the antenna to radiate effectively at broadside frequencies
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A single-layer substrate integrated directive broadside beam leaky-wave antenna is provided. Opposite ends of a leaky-wave structure are fed with anti-phase versions of a common signal, resulting in broadside frequencies being set apart from the open stopband. To achieve this, the common signal can be split into two equal length paths, one including a perfect electrical conductor (PEC) reflector and the other including a perfect magnetic conductor (PMC) reflector. Alternatively, the common signal can be split into two paths which differ in length by a half wavelength. A power splitter and feed horns can be used in the respective paths. The leaky-wave structure may have transverse slots which increase in width toward a midpoint of the structure. The antenna can be formed in a single planar portion of a lithographic structure, for example by patterning an upper conductive layer thereof.