Antenna Theory And Design

소형 안테나 ( Small Antennas )

In this paper, internal low-volume antenna structures for mobile terminals are studied. The work concentrates on the possibilities to reduce the volume of mobile terminal antenna elements by efficiently utilizing the radiation of the currents on the mobile terminal chassis. Essentially nonresonant coupling elements are used to optimally couple to the dominating char- acteristic wavemodes of the chassis. The antenna structures are tuned to resonance with matching circuits. During the last few years, the approach has achieved growing interest—also among industrial manufacturers of mobile terminals. There exist, how- ever, no systematical feasibility and performance studies of the idea. During the work, two antenna models with very low-volume coupling elements are designed and in total four prototypes are constructed. The simulation and measurement results show that the studied antenna concept is a very promising alternative for traditional antenna technologies. The presented analysis provides useful and novel information for the designs of the future low-pro- file and low-volume mobile terminal antennas.

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Coupling element based mobile terminal antenna structures

A method, transceiver integrated circuit (IC), and communications device for generating antenna tuning states derived from a pre-established trajectory of tuning states to adjust a detected signal level towards a preset, given value. A tuning state generation (TSG) controller determines whether a detected signal level matches a given value. If the detected signal level does not match the given value, the TSG controller selects an initial preset tuning state from a pre-established trajectory corresponding to a pre-identified operating condition that best matches a current operating condition. The TSG logic forwards the initial preset tuning state to the antenna tuner to trigger impedance transformation. Following generation of the initial preset tuning state, the controller receives an updated detected signal level. If the updated detected signal level fails to match the given value, the controller generates an incremental tuning state that is interpolated between the initial and a final preset tuning states.

Antenna tuning on an impedance trajectory

This letter proposes a new design of millimeter-wave (mm-Wave) array antenna package with beam steering characteristic for the fifth-generation (5G) mobile applications. In order to achieve a broad three-dimensional scanning coverage of the space with high-gain beams, three identical subarrays of patch antennas have been compactly arranged along the edge region of the mobile phone printed circuit board (PCB) to form the antenna package. By switching the feeding to one of the subarrays, the desired direction of coverage can be achieved. The proposed design has >10-dB gain in the upper spherical space, good directivity, and efficiency, which is suitable for 5G mobile communications. In addition, the impact of the user's hand on the antenna performance has been investigated.

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A Switchable 3-D-Coverage-Phased Array Antenna Package for 5G Mobile Terminals

For the reception of terrestrial television, traditionally Yagi or whip antennas are used. Due to their large size they cannot be used in the reception of digital television on handheld devices (DVB-H), which operate at the frequency band 470 – 702 MHz. The DVB-H system is under development and small internal antenna solutions for handheld devices are not yet available. Due to the long wavelengths, any antenna placed inside a portable terminal will be electrically small. The antenna volume is the fundamental factor determining its performance. With traditional microstrip antennas such as PIFAs the required bandwidth could not be obtained inside a pocket-size terminal. Therefore, a broadband planar antenna structure for a DVB-H receiver is presented in this paper. The antenna structure is based on the compact coupling element antenna structure [1] that was earlier applied for GSM systems [2].

Antenna for Handheld DVB Terminal

This letter reports a systematic simulation study of the performance of mobile terminal antennas in the vicinity of the user's hand. The effects of antenna dimensioning and antenna location on the ground plane of the device are demonstrated. The studied performance parameters are quality factor, radiation efficiency, and frequency detuning. Based on the results, beneficial approaches and general guidelines for antenna designs with a reduced effect of the user's hand can be given. For instance, it is shown that the radiation efficiency with the user's hand stays nearly constant (variation <;0.2 dB) despite the changes in the antenna element height (2-6.6 mm at 900 and 2000 MHz).

Mobile Terminal Antenna Performance With the User's Hand: Effect of Antenna Dimensioning and Location

In this letter, it is shown how the behavior of a capacitive coupling element (CCE)-based mobile terminal antenna can be modeled at the UHF band as a combination of the separate wavemodes of the structure. The proposed equivalent circuit model improves the general understanding of the operation of the antenna structure. It can be used for analyzing the combined performance of the capacitive coupling element and terminal chassis, but it also helps in analyzing how different parts of the antenna structure contribute to the impedance and radiation.

Broadband Equivalent Circuit Model for Capacitive Coupling Element–Based Mobile Terminal Antenna

This paper discusses the issues in antenna design for future mobile communications terminals caused by the addition of more and more antennas into the devices. There can be more than 10 different radios in the terminal and some of them will utilise adaptive antenna systems with more than 5 antennas. Thus it is possible that a future terminal device will have more than 20 antennas. This can be either a threat or an opportunity depending on the viewpoint of e.g. a terminal manufacturer or an antenna manufacturer, respectively. The challenges connected to the large number of antennas are the volume required by the antennas in a small terminal, coupling between the antennas and finding locations for the antennas where user interaction is low. The possible solutions include minimisation of the size of antenna elements, re-use of the same antennas in many systems, and methods to isolate the antenna elements from each others.

More than 20 antenna elements in future mobile phones, threat or opportunity?

The upcoming standards of wireless communications result in additional and more stringent requirements for antennas in mobile phones. In this paper, we present a frequency-reconfigurable antenna that could potentially be suited for future mobile devices. Frequency reconfigurability is achieved through a cluster of mutually coupled antenna elements that is excited with frequency-dependent weights using a multichannel transceiver. We report a mobile handset antenna cluster measuring 15 $\times $ 15 $\times $ 1.6 mm3 that covers the frequency bands of 1.7–2.7, 3.3–4.5, and 5.475–6.425 GHz with an antenna efficiency better than 90%. The operation of the antenna cluster is experimentally verified by feeding all the antenna elements with proper weights using tailor-made power splitters that represent a multichannel transceiver with adjustable amplitude and phase in each branch. The results obtained with the feed networks suggest the feasibility of the reconfigurability concept and pave way for codesign of the antenna and the transceiver.

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Jari Holopainen

Papers

Antenna for Handheld DVB Terminal

Mobile Terminal Antenna Performance With the User's Hand: Effect of Antenna Dimensioning and Location

Broadband Equivalent Circuit Model for Capacitive Coupling Element–Based Mobile Terminal Antenna

More than 20 antenna elements in future mobile phones, threat or opportunity?

Frequency Reconfigurable Multiband Handset Antenna Based on a Multichannel Transceiver