Antenna Device With Short-Circuited Loop For High Isolation
Solution Overview
Problem
Existing antenna devices face challenges in ensuring high isolation between antennas operating at the same or adjacent frequencies, particularly in small-sized communication apparatuses, where mutual interference is significant due to limited spacing and insufficient frequency isolation.
Innovation Solution
The antenna device incorporates a ground conductor and linear antennas with a monopole and loop configuration, where the loop antenna is short-circuited to the ground, allowing for phase adjustment of currents to reduce interference, and includes chip reactance elements to enhance isolation and reduce size, while differing resonant frequencies between antennas further improve isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single high-frequency front-end module processes communication signals of two adjacent frequencies, then the device size is reduced, but coupling between the two antennas becomes a problem and mutual interference increases
Solution Approach 1:
The patent introduces a ground conductor as an intermediary element between the two antennas. This ground conductor serves as a mediator to control current flow paths, directing currents from each antenna through separate ground connections rather than allowing direct coupling between antennas, thereby reducing mutual interference while maintaining compact device size
Solution Approach 2:
The patent segments the current path by providing separate ground connections for each antenna. The first antenna connects to ground through a first ground conductor, and the second antenna connects through a second ground conductor, dividing the current flow paths to prevent coupling between antennas operating at adjacent frequencies
2Length of moving object
If the distance between two antennas is reduced in a small-sized communication apparatus, then the device size is reduced, but isolation between antennas deteriorates and mutual interference becomes more serious
Solution Approach 1:
The ground conductor acts as an intermediary that enables close antenna placement while maintaining isolation. By providing dedicated ground paths for each antenna, the system can reduce the physical distance between antennas without sacrificing isolation performance, as the ground conductors manage current flow to prevent coupling
3Loss of energy
If the loop antenna is connected to ground at the end portion adjacent to the monopole antenna, then current flowing to ground is reduced, but sufficient isolation cannot be ensured in certain frequency bands like 2400 MHz
Solution Approach 1:
The patent introduces a separate ground conductor as an intermediary element that provides an additional current path. Instead of relying solely on the loop antenna's ground connection, the system uses the ground conductor to manage current flow, enabling better isolation control in frequency bands like 2400 MHz where the conventional configuration fails
Solution Approach 2:
The patent adds a spatial dimension to the current path management by introducing a ground conductor that extends in a direction different from the antenna elements. This dimensional addition provides a new pathway for current flow that enhances isolation without affecting the antenna structures themselves
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 configuration achieves high isolation between antennas, suppressing coupling and maintaining effective communication across various frequency bands, including the 2400 MHz band, thereby enhancing reception sensitivity and reducing antenna size.
Implementation Method 1
a current is generated that flows from a short-circuit point, at which the loop antenna is short-circuited to the ground conductor, to the ground conductor
Implementation Method 2
by adjusting the phase of the current flowing from the short-circuit point of the loop antenna to the ground conductor, it is possible to weaken the current flowing from the feeding point of the first antenna to the ground at the feeding point of the second antenna
Data Source
AI summary
An antenna device including a ground conductor and first and second antennas. The first and second antennas are linear antennas and have respective feeding points at ends on a side of the ground conductor. The first and second antennas perform transmission/reception at first and second frequencies that are adjacent to each other, respectively. Moreover, the first antenna includes a first monopole antenna and a loop antenna branched off from the first monopole antenna. An end of the loop antenna opposing a branching point at which the loop antenna is branched off from the first monopole antenna is short-circuited between the feeding points of the first and second antennas on the ground conductor.