Multiband Antenna with High Impedance Portion for Compact Handheld Devices
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Solution Overview
Problem
The miniaturization of cellular antennas in handheld devices is challenging due to increased operating demands, particularly with the introduction of the LTE standard, which requires antennas to cover large frequency bands while maintaining performance and fitting within limited space, often resulting in inferior performance and size constraints.
Innovation Solution
A multiband antenna device with a conductive elongate antenna element configured to extend along the edges of a groundplane, featuring a high impedance portion positioned away from the user's hand to reduce interference, and additional extending portions to achieve lower resonant frequencies, allowing for efficient operation across multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna is miniaturized to accommodate larger LCD and battery, then the device can fit more consumer-focused components, but the antenna performance deteriorates and operating frequency ranges are reduced
Solution Approach 1:
The antenna element extends beyond the groundplane edges in three-dimensional space, utilizing vertical and lateral dimensions to achieve longer electrical length without increasing the groundplane area. This allows the antenna to maintain multiband operation capability while the groundplane remains compact.
Solution Approach 2:
The antenna element is divided into multiple portions (first portion extending along first edge, second portion extending along second edge, third portion double-backing) that can be independently configured. This segmentation allows optimization of each segment for different frequency bands while maintaining overall compactness.
2Adaptability or versatility
If two cellular antennas are fitted for MIMO applications, then LTE requirements are met, but the space available for each antenna is severely limited
Solution Approach 1:
The antenna design merges multiple functional portions into a single integrated antenna element that can operate across multiple frequency bands, reducing the need for separate antennas for different functions while maintaining MIMO capability through proper positioning.
Solution Approach 2:
The antenna element is designed to be universal by covering multiple frequency bands (LTE 700MHz, 800MHz, 900MHz, 1800MHz, 2100MHz, 2600MHz) with a single structure, allowing one antenna to perform multiple functions that would traditionally require multiple specialized antennas.
3Area of stationary object
If the antenna is positioned in limited space areas, then the LCD and battery can be maximized, but the antenna performance becomes inferior and is susceptible to user hand interference
Solution Approach 1:
The high impedance portion is extracted and positioned away from the user's hand area, removing the problematic element that causes performance degradation during normal use while retaining the essential antenna functionality in the compact groundplane area.
4Adaptability or versatility
If the antenna element is extended to achieve lower resonant frequencies, then the frequency coverage is improved, but the antenna physical size increases
Solution Approach 1:
The antenna utilizes three-dimensional positioning by extending beyond groundplane edges and employing vertical elements, allowing the electrical length to be increased for lower frequency operation without proportionally increasing the horizontal footprint area.
Solution Approach 2:
The antenna employs meandering and bent configurations instead of straight lines, allowing the electrical path length to be extended within a compact physical envelope, achieving lower resonant frequencies without linearly increasing the overall antenna dimensions.
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 antenna device achieves efficient multiband operation across 690MHz to 2780MHz with improved performance by positioning the high impedance portion away from the user's hand and extending the antenna element to lower resonant frequencies, enabling compact design suitable for MIMO applications within handheld devices.
Implementation Method 1
a first resonant frequency determined by a length of the antenna element from the feeding point to a high impedance portion of the antenna element, and a second resonant frequency determined by a length of the antenna element from the feeding point to the terminus
Implementation Method 2
the second portion of the antenna element having a terminus being a rectangular high impedance portion, the high impedance portion of the antenna element being positioned between the first edge of the ground plane and the first portion of the antenna element, and being sized and shaped to form a narrow gap between the terminus of the second portion of the antenna element and the first portion of the antenna element that electromagnetically couples the first and second portions of the antenna element
Data Source
Figure 1~2
Figure 3(a)~3(e)
Figure 4
AI summary
There is disclosed a multiband antenna device comprising a conductive elongate antenna element configured for electrical connection to a conductive groundplane at a grounding point, and for electrical connection to a radio transmitter/receiver at a feeding point. The antenna element comprises a first portion and a second portion. The first portion is configured to extend in a first direction along a first outside edge of the groundplane, and then in a second direction along a second outside edge of the groundplane. The second portion of the antenna element is configured to double back next to the first portion in a third, substantially counter-parallel direction back along the second outside edge of the groundplane, and then in a fourth direction along the first outside edge of the groundplane. The second portion of the antenna element terminates with a high impedance portion, and the high impedance portion of the antenna element is positioned between the first edge of the ground plane and the first portion of the antenna element so as to form a narrow gap that electromagnetically couples the first and second portions of the antenna element.