Multi-Beam Antenna Feed Network Reflection Cancellation
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Solution Overview
Problem
Multi-beam antennas face significant port-to-port coupling issues due to reflected RF signals, leading to interference and potential damage, despite radiating elements being designed for high efficiency to minimize this coupling.
Innovation Solution
A cancellation circuit is introduced in the feed network of multi-beam antennas, utilizing directional couplers and phase delays to extract and inject RF signals in opposite phases between beam ports, thereby canceling out reflected signals before they reach the receive paths of other beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If radiating elements are designed to radiate at high efficiency to minimize beam-to-beam coupling, then radiation efficiency is improved, but port-to-port coupling due to reflected signals still occurs causing interference and potential damage to receivers
Solution Approach 1:
The cancellation circuit applies preliminary anti-action by extracting the transmitted RF signal, delaying it to match the reflection path timing, inverting its phase by 180 degrees, and injecting it into the opposing beam port before the reflected signal can cause interference. This preemptive cancellation neutralizes the harmful reflected signals that would otherwise couple into receiver paths.
Solution Approach 2:
The invention converts the harmful reflected RF signals into a beneficial cancellation mechanism. By extracting the original transmit signal, processing it through delay and phase inversion, and re-injecting it into the opposing port, the system transforms what would be harmful reflections into useful cancellation signals that actively neutralize the interference.
2Reliability
If beam-to-beam isolation is increased to prevent interference between transmitting and receiving beams, then receiver protection is improved, but the complexity of the feed network increases due to additional cancellation circuits
Solution Approach 1:
The cancellation function is segmented into modular components: directional couplers for signal extraction, delay lines for timing adjustment, phase inverters for 180-degree phase shift, and combiners for signal re-injection. Each beam pair has its own independent cancellation circuit, allowing the system to achieve high isolation while maintaining manageable complexity through functional segmentation.
3Object-affected harmful factors
If cancellation circuits are added to reduce reflected signal coupling, then beam-to-beam isolation is improved, but the device complexity increases due to additional components in the feed network
Solution Approach 1:
The cancellation circuit implements feedback by continuously monitoring the transmitted RF signal through directional couplers, processing this feedback signal through delay and phase inversion, and re-injecting it into the opposing beam port. This closed-loop feedback mechanism dynamically cancels reflected signals that couple between beams, improving isolation while using standard feedback control principles.
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 solution effectively reduces beam-to-beam interference by ensuring that reflected transmit RF signals are partially or fully canceled, enhancing the isolation between beams and preventing damage to receivers.
Implementation Method 1
The cancellation circuit is configured to extract a portion of a RF signal on the first beam port, add phase delay, and inject the extracted, delayed signal from the first beam port onto the second beam port
Implementation Method 2
This is a result of a transmit RF signal of one beam being reflected at the radiating elements, and the beam-forming network coupling the reflected signal through the receive path of a second beam
Data Source
AI summary
A feed network for a multi-beam antenna is provided, including a first beam port, a second beam port, a beam-forming network coupled to the beam ports, and a cancellation circuit. The cancellation circuit is coupled to the first beam port and the second beam port before the beam-forming network. The cancellation circuit extracts a portion of a RF signal on the first beam port, adds phase delay, and injects the extracted, delayed signal from the first beam port onto the second beam port, and extracts a portion of a RF signal on the second beam port, adds phase shift, and injects the extracted, delayed signal from the second beam port onto the first beam port. In one example of the invention, the cancellation circuit comprises a first directional coupler on a first beam input path, a transmission line, a second directional coupler on the second beam input path.