Dual-Band Filtering Patch Antenna With Embedded U-Shaped Patches
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Solution Overview
Problem
Current dual-band filtering antennas for LTE MIMO systems face challenges in achieving low-profile designs with independent control of operating frequencies and sufficient out-of-band radiation nulls, leading to insertion loss and inadequate skirt selectivity.
Innovation Solution
A low-profile dual-band filtering patch antenna design featuring a first U-shaped patch embedded within a second U-shaped patch, combined with a multi-stub microstrip line that forms different feeding structures for upper and lower frequency bands, allowing for independent control of operating frequencies and generation of radiation nulls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a dual-band antenna and filter are designed separately and cascaded together, then dual-band operation is achieved, but the operating frequencies cannot be controlled individually and insertion loss increases
Solution Approach 1:
The patent combines the antenna and filter into a single integrated structure where the patch antenna elements serve dual purposes: radiating elements and filtering components. The multi-stub microstrip lines are integrated directly with the patch structures, eliminating the need for separate cascaded filter and antenna modules, thereby reducing insertion loss while maintaining dual-band operation capability
2Reliability
If extra filtering circuits are inserted to the antenna feeding networks, then filtering performance is improved, but antenna gains are degraded
Solution Approach 1:
The filtering function is merged directly into the antenna feeding network through integrated multi-stub microstrip structures. These stubs are embedded within the patch antenna geometry itself, allowing the feeding network to provide both impedance matching and filtering functions simultaneously, thereby improving filtering performance without degrading antenna gain
3Reliability
If a 2-layer PCB structure is used for dual-band filtering antenna, then electromagnetic coupling is achieved, but the low-profile requirement is not met
Solution Approach 1:
The patent transitions from a 2-layer PCB structure to a 3D embedded structure where multi-stub microstrip lines are integrated within the patch antenna geometry. This dimensional change allows electromagnetic coupling to be achieved through spatial arrangement and geometric configuration rather than through multiple PCB layers, thereby maintaining coupling performance while reducing profile height to meet low-profile requirements
4Device complexity
If single-band filtering antennas are designed, then simple structure is achieved, but dual-band specifications of carrier aggregation cannot be fulfilled
Solution Approach 1:
The patent designs the patch antenna with multi-stub microstrip lines that can operate across multiple frequency bands. The stub structures are configured to support both fundamental and harmonic resonances, enabling the single antenna structure to fulfill dual-band carrier aggregation specifications while maintaining relative structural simplicity through unified geometric design
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 design achieves quasi-elliptic dual-band responses with minimal insertion loss, high in-band gains, and significant out-of-band radiation rejection, meeting the requirements for LTE CPEs with a compact and flexible configuration.
Implementation Method 1
a multi-stub microstrip line, the first U-shaped patch having a smaller size is embedded in the second U-shaped patch having a larger size; wherein, when operating at the upper frequency bands, the multi-stub microstrip line forms a feeding structure, and when operating at the lower frequency bands, the multi-stub microstrip line and the first U-shaped patch form the feeding structure
Implementation Method 2
a first U-shaped patch operating at upper frequency bands, a second U-shaped patch operating at lower frequency bands
Data Source
AI summary
A low-profile dual-band filtering patch antenna and its application to LTE MIMO system are disclosed. By using two embedded U-shaped radiating patches and a multi-stub microstrip feed-line, two operating bands and four radiation nulls can been generated and individually controlled, the design is thus very simple and flexible. Based on the proposed low-profile dual-band filtering patch antenna, a MIMO antenna with a very low profile, low mutual coupling and low ECCs has been presented.