Sparse Multistatic Antenna Arrays for Near-Field Synthetic Imaging
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Solution Overview
Problem
Existing synthetic imaging techniques require a large number of antennas and suffer from antenna coupling issues, signal isolation challenges, and path length errors, particularly in near-field applications, limiting their efficiency and scalability.
Innovation Solution
The sparse multi-static array configuration uses two linear arrays with unique spacing intervals, allowing for reduced antenna counts and maintaining dedicated transmitters and receivers, which enables dense uniform sampling and efficient image reconstruction with minimal artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If antennas are placed uniformly along the array axis with close spacing (λ/2) to satisfy spatial sampling criterion, then sampling density is improved, but antenna coupling problems increase and antenna gain decreases
Solution Approach 1:
The array is segmented into two separate linear arrays: a transmit array and a receive array. This segmentation allows each array to have larger element spacing (2Δ) while maintaining the required effective sampling density (Δ), thereby reducing antenna coupling problems while preserving measurement precision.
Solution Approach 2:
The system transitions from a single array configuration to a two-array configuration separated by a distance Δ. This dimensional change allows the effective sampling spacing to be half the physical element spacing, enabling larger antenna spacing without compromising sampling density.
2Object-generated harmful factors
If separate transmit and receive arrays are used with spacing 2Δ, then antenna coupling is reduced and antenna gain increases, but the number of antennas required increases
Solution Approach 1:
Each antenna element in both arrays is designed to function simultaneously as both a transmitter and a receiver. This multi-functionality allows the system to achieve the performance benefits of separate transmit and receive arrays while using fewer total antenna elements, as each antenna serves dual purposes.
3Quantity of substance
If each antenna functions as both transmitter and receiver, then the number of antennas is reduced, but signal isolation challenges increase due to difficulty in separating transmit from receive signals
Solution Approach 1:
A switching network is introduced as an intermediary component that sequentially connects each antenna to the transceiver in transmit and receive modes. This switching mechanism effectively isolates the receive signal from the transmit signal by ensuring only one mode is active at a time, resolving the signal isolation challenge while maintaining antenna multi-functionality.
Solution Approach 2:
The system uses periodic switching between transmit and receive modes for each antenna. This time-division approach creates clear temporal separation between transmit and receive operations, enabling effective signal isolation without requiring additional physical isolation components.
4Difficulty of detecting and measuring
If directional couplers or circulators are used to separate transmit and receive signals, then signal isolation is improved, but additional losses are introduced
Solution Approach 1:
The system replaces passive signal separation components (directional couplers or circulators) with an active switching mechanism. This substitution eliminates the inherent losses associated with couplers and circulators while achieving equivalent or superior signal isolation through time-division multiplexing controlled by the switching network.
Data Source
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AI summary
An apparatus for synthetic imaging of an object is disclosed. The apparatus includes a plurality of transmitter elements spaced apart by a first distance in a first column and a plurality of receiver elements spaced apart by a second distance in a second column. The first distance and the second distance are different. The plurality of transmitter elements is a non-integer multiple of the plurality of receiver elements, and the plurality of receiver elements is a non-integer multiple of the plurality of transmitter elements.