Microstrip Antenna Array Asymmetry for Tx/Rx Isolation
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Solution Overview
Problem
Conventional decoupling structures for antenna arrays in high-frequency base stations are large and unsuitable for compact arrays or MIMO applications, leading to challenges in isolating transmit and receive panels effectively.
Innovation Solution
An antenna apparatus utilizing microstrip antenna elements with a short-circuit pillar to excite first- and second-order modes, generating asymmetric radiation signals with radiation nulls, and incorporating electromagnetic band gap structures to suppress coupling and enhance isolation between transmit and receive panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional decoupling structures (isolation wall or choke groove) are used to improve isolation between transmit and receive panels, then isolation performance is improved, but the device size becomes large and unsuitable for compact arrays or MIMO applications
Solution Approach 1:
The patent changes the working parameters by operating the antenna at a frequency between the first-order mode frequency and second-order mode frequency. This parameter change enables the generation of asymmetric radiation patterns with nulls in specific directions, achieving decoupling without requiring large physical structures. The frequency parameter selection is critical to simultaneously exciting both modes and creating the desired radiation characteristics.
Solution Approach 2:
The patent deliberately creates asymmetric radiation patterns by simultaneously exciting the first-order mode and second-order mode of the microstrip antenna element. The asymmetric radiation signal has a radiation null in a preset area, which achieves decoupling between transmit and receive panels. This asymmetric approach eliminates the need for symmetric conventional decoupling structures like isolation walls, thereby reducing the overall device size.
2Reliability
If conventional decoupling structures are loaded to achieve decoupling between transmit and receive panels, then coupling suppression is improved, but the device complexity increases due to additional components
Solution Approach 1:
The microstrip antenna element serves multiple functions simultaneously: it radiates electromagnetic waves for communication and generates asymmetric radiation patterns with nulls for decoupling. By simultaneously exciting the first-order mode and second-order mode, the same antenna element achieves both transmission/reception and decoupling functions, eliminating the need for separate decoupling structures and reducing device complexity.
3Reliability
If the operating frequency is set between first-order mode frequency and second-order mode frequency to generate asymmetric radiation signal, then isolation between panels is improved, but the bandwidth may be limited
Solution Approach 1:
The patent uses partial action by selectively exciting specific modes (first-order and second-order modes) rather than all possible modes. This selective mode excitation achieves the desired asymmetric radiation pattern and decoupling effect while operating within a specific frequency range. The approach balances the need for isolation with practical bandwidth considerations by focusing energy on the critical modes that produce the decoupling effect.
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 solution improves isolation between transmit and receive panels by suppressing radiation power at specific angles, enhancing communication performance and reducing the size of the antenna elements, suitable for compact arrays and MIMO applications.
Implementation Method 1
each microstrip antenna element is configured to simultaneously excite a first-order mode and a second-order mode through a radiation patch, to generate an asymmetric radiation signal at an operating frequency
Implementation Method 2
The asymmetric radiation signal has a radiation null in a preset area
Implementation Method 3
the short-circuit pillar penetrates the dielectric substrate and connects the other end of the radiation patch to the metal bottom plate
Data Source
Figure 1
Figure 2A
Figure 2B~3B
AI summary
An antenna apparatus and an antenna system are provided. The antenna apparatus is an antenna array including a plurality of microstrip antenna elements. Each microstrip antenna element includes a dielectric substrate, a radiation patch, a metal bottom plate, a feeding probe, and a short-circuit pillar. The radiation patch is located on an upper surface of the dielectric substrate, the metal bottom plate is located on a lower surface of the dielectric substrate, the feeding probe penetrates the dielectric substrate and connects one end of the radiation patch to the metal bottom plate, and the short-circuit pillar penetrates the dielectric substrate and connects the other end of the radiation patch to the metal bottom plate. The short-circuit pillar is disposed on the radiation patch, and a first-order mode and a second-order mode are simultaneously excited, so that radiation power of the microstrip antenna element in a preset area can be suppressed, and a radiation null can be generated. Therefore, a signal radiated by the microstrip antenna element can be asymmetric, to implement asymmetry of the antenna array. The antenna system formed by using the antenna array can implement coupling suppression on a transmit array and a receive array of the antenna system, to improve isolation between the transmit array and the receive array.