True Time Delay Compensation for Phased Array Reflector Antennas
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Solution Overview
Problem
Phased array fed reflector (PAFR) antenna systems face coherence and timing issues due to path length differences between the reflector and phased array elements, leading to reduced throughput capacity and interference in wideband communication systems, particularly in satellite communications.
Innovation Solution
The implementation of true time delay (TTD) compensation elements coupled to the phased array antenna elements to account for free-space path length differences, allowing for accurate beam steering and reducing the 'squint' effect across various frequencies, thereby enhancing the throughput capacity and efficiency of PAFR antenna systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a reflector is added to increase directivity without adding more antenna elements, then the directivity and geographic separation of beams are improved, but path length differences between the reflector and phased array elements cause coherence and timing issues
Solution Approach 1:
The patent applies parameter changes by introducing time delay compensation that varies across different antenna elements. Each element receives a customized time delay value based on its specific path length difference to the reflector, thereby correcting the coherence and timing issues while preserving the directivity enhancement provided by the reflector configuration.
Solution Approach 2:
The patent implements local quality by providing individualized time delay compensation to each antenna element or zone rather than a uniform compensation. This localized approach addresses the specific path length differences experienced by different parts of the phased array, ensuring optimal coherence and timing correction across the entire system.
2Productivity
If wideband frequency spectrum is utilized to increase throughput capacity, then the data transmission capability is improved, but the path length differences cause increased interference and reduced beam steering accuracy
Solution Approach 1:
The patent utilizes parameter changes by implementing frequency-dependent time delay compensation. The time delay values are adjusted based on the operating frequency within the wideband spectrum, allowing the system to maintain accurate beam steering and reduce interference across the entire frequency range, thereby enabling effective wideband operation and increased throughput capacity.
3Weight of stationary object
If the phased array is positioned away from the focal point to reduce size and weight, then the satellite platform constraints are relaxed, but the path length differences between elements and reflector increase
Solution Approach 1:
The patent applies parameter changes by calculating and implementing customized time delay compensation values that account for the increased path length differences resulting from the compact phased array positioning. This compensation mechanism allows the system to maintain coherent operation despite the larger path variations, enabling size and weight reduction without sacrificing performance.
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 use of TTD compensation significantly improves the coherence and timing of beam steering, increasing the throughput capacity and reducing interference in wideband communication systems by ensuring that all antenna elements are effectively utilized across the available frequency spectrum, thus enhancing the performance of PAFR antennas in satellite communications.
Implementation Method 1
time delays associated with free-space path length differences between the phased array of antenna elements and the reflector
Data Source
AI summary
Systems, devices, and methods for determining and applying true time delay (TTD) values for compensating for free-space path length differences between a phased array and a reflector in wideband communication are disclosed. TTD values are determined for individual and groups of antenna elements in phased array fed reflector (PAFR) antennas based distances from a focal region of the reflector. The distance from the focal region of the reflector and the offset of the phased array from the reflectors focal plane can be used to determine path length differences. Corresponding TTD values for antenna elements are then determined based on the path length difference associated with the antenna elements. Each antenna element can be coupled to a TTD element to provide the corresponding TTD value to the signals received by and generated by the antenna elements of the phased array. The TTD elements include transverse electromagnetic (TEM) mode mechanisms.