Simultaneous Transmit Receive Antenna Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing antenna systems for simultaneous transmit and receive (STAR) operations face challenges in achieving high isolation between transmit and receive signals, particularly in omnidirectional patterns, which affects the efficiency and effectiveness of wireless communications.
Innovation Solution
A STAR antenna system is designed with a ring array of transmit antenna elements and a receive antenna element, where the transmit antenna elements are equally angularly distributed with phases increasing linearly and differing by 180 degrees, and are positioned with a ground plane and an electrically-conductive cylinder to increase isolation, allowing for partial obscuration of the path between transmit and receive elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a ring array antenna is used for omnidirectional transmit and receive operations, then the coverage area is improved, but the isolation between transmit and receive signals deteriorates
Solution Approach 1:
The antenna system segments the omnidirectional coverage into four directional quadrants using four antenna elements arranged in a ring. Each element covers a specific angular sector (90 degrees), and by selectively activating different elements based on the desired coverage direction, the system achieves both omnidirectional capability and improved transmit-receive isolation through spatial separation
Solution Approach 2:
The patent applies local quality by creating direction-dependent radiation patterns where different parts of the ring array serve different functions. Specifically, when transmitting from one element, the opposing element is used for receiving, creating a local null in the receive pattern toward the transmit element. This localized pattern control achieves high isolation (greater than 20 dB) while maintaining overall omnidirectional coverage capability
2Volume of moving object
If transmit and receive antennas are collocated for compact design, then the device size is reduced, but the mutual coupling between antennas increases
Solution Approach 1:
The patent employs asymmetry in the phase distribution and amplitude weighting of the ring array elements to create directional radiation patterns with nulls in specific directions. By asymmetrically controlling the phase and amplitude of each element, the system creates transmit patterns with nulls toward the receive antenna location and vice versa, achieving high isolation despite collocated positioning
Solution Approach 2:
The system transitions from traditional vertical polarization to horizontal polarization in the azimuth plane, utilizing the angular dimension around the ring array. By distributing elements around a ring and controlling their phase relationships, the system creates three-dimensional radiation patterns with nulls in specific directions, achieving isolation without increasing physical separation distance
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 system achieves high isolation between transmit and receive signals, enabling efficient simultaneous operation with improved radiation patterns and reduced mutual coupling, suitable for various frequency bands including Wi-Fi, cellular, and radar applications.
Implementation Method 1
a ring array of transmit antenna elements... each transmit antenna element having a phase relative to a phase of the other transmit antenna elements such that the phases increase linearly around an array circumference of the ring array
Implementation Method 2
positioned with a ground plane and an electrically-conductive cylinder to increase isolation, allowing for partial obscuration of the path between transmit and receive elements
Implementation Method 3
For an even number of antenna elements in the ring array, each opposing pair of antenna elements is fed anti-phase, that is, the two antenna elements differ in phase by 180°, to generate a radiation pattern having a null at the center of the ring array
Data Source
AI summary
Described is a simultaneous transmit and receive antenna system having a ring array of transmit antenna elements and a receive antenna element disposed on an axis that is perpendicular to and passing through the center of the ring array. Alternatively, the ring array includes receive elements and a transmit antenna element is disposed on the axis perpendicular to the ring array. Opposite antenna elements in the ring array differ in phase by 180° so that a radiation pattern null occurs at the antenna element at the center of the ring array. Also included are at least one ground plane and an electrically-conductive cylinder disposed on the perpendicular axis inside the ring array to provide a high degree of isolation between the transmit and receive antenna elements. The system may be configured for wireless communications, for example, according to WIFI IEEE standard 802.11 or WIMAX IEEE standard 802.16.