Li-Ruei Kuo

INVESTIGATIONS OF ISOLATION IMPROVEMENT TECHNIQUES FOR MULTIPLE INPUT MULTIPLE OUTPUT (MIMO) WLAN PORTABLE TERMINAL APPLICATIONS

Various isolation improvement techniques for MIMO WLAN card bus applications consisted of three closely spaced loop antennas are presented and investigated both numerically and experimentally in this paper. The proposed techniques are easily implemented and proven effective to achieve high isolation among the antennas which is a must for MIMO terminals to receive uncorrelated signals with good system throughputs.

Characteristic Evaluation of an Active Patch Antenna Structure with an Embedded LNA Module for GPS Reception

The concept of antenna design with an embedded LNA module is proposed in this work. To demonstrate the concept, a microstrip patch antenna for GPS reception is considered. The antenna is a conventional patch antenna with corners truncated to produce RHCP radiation for GPS reception at 1.575 GHz. A cavity is formed within the substrate of the antenna to accommodate the LNA module so that the built-in LNA may enhance the antenna reception capability without adding external circuits. The resulting patch has the same footprint and thickness as an ordinary passive patch. Simulations and measurements of the prototype antenna indicate that the built-in LNA module introduces no significant changes to the antenna properties except slight shifts on the resonance frequency, which can be corrected by rescaling. The proposed antenna configuration is an attractive option in practical applications for making antennas with small footprints and large gains.

Design of reflectarray antennas to achieve an optimum near‐field radiation for RFID applications via the implementation of SDM procedure

This paper presents the design of reflectarray antennas to radiate an optimum near-field distribution by using the procedure of steepest decent method to synthesize the impressed phases of reflectarray elements. In particular, the closed-form formulations used in the electromagnetic modeling were developed for an efficient design. The design was further implemented to realize a reflectarray of microstrip patch elements, which is illuminated by the radiation of a feed antenna at the 2.4 GHz band in the radio frequency identification applications. Numerical investigations as well as experimental measurements over a prototype are presented to validate the feasibility of the developed models and the implemented antenna structure.

Near-zone focused radiations of reflectarray antennas for RFID applications at 0.9 and 2.4 GHz

A dual-band design of reflectarray antennas for the RFID applications operated at 0.9 and 2.4 GHz is presented. In this design, the fields radiated from the antenna will focus in the near-zone of array aperture. Numerical investigations on the radiation characteristics of this reflectarray, as well as an experimental validation, are presented to demonstrate its feasibility.

MIMO loop antennas and their isolations in WLAN card applications

A design of three loop antennas for MIMO [1] applications on a WLAN card is investigated. These antennas are printed on a FR4 substrate and oriented in a way to exhibit distinguishable propagation characteristics. The limited space between antenna locations causes strong mutual couplings that may complicate MIMOs signal process. Thus, potential approaches [2,3] to reduce the mutual coupling are examined by considering slots cut from the ground plane and placing resistive cards [4] between the antennas, whose effects on the antenna performances and data communications are investigated and presented in this paper. Realistic system implementation shows that this design simultaneously provides distinguishable scattering characteristics and effective isolations, and improves overall communication qualities.

An Active Patch Antenna with Embedded LNA Module

In this work, an LNA module is moved into a corner-truncated patch antenna, which is intended for GPS reception use. A cavity is formed within the substrate of the patch to accommodate the LNA module. The built-in LNA enhances the antenna reception capability without adding external circuits. Hence, the resulting patch has the same footprint and thickness as ordinary passive patches. Simulations and measurements on prototype antenna indicate that the built-in LNA module imposes limiting influences on the antenna properties, which can be corrected by rescaling the patch, and is hence an attractive option for making small antennas with large gains

Design of ellipsoidal reflector antennas for near-field RFID applications at UHF band

This paper presents the design of an ellipsoidal reflector antenna for the RFID applications at UHF band, which can be potentially integrated with a dome-shape building structure. Due to the dual-focus radiation characteristics in the ellipsoid near-field region, the feed located at one of the two foci can create a focused field distribution around the other focus, which is located in the ground area covered by the dome. In this case, the radiated energy will be confined so minimizing the interference effects outside of the targeted area.

Shaped reflector antennas for outdoor BTS of 4G/5G mobile communications

This paper presents an effective design of reflector antennas to radiate beam patterns fulfilling the coverage need of base station antenna (BSA) system in the 4G/5G mobile communication. A mechanical feeds titling mechanism has been implemented in conjunction with the synthesis of reflecting surface to provide remote beam tilting function for dynamic cell adjustments. The numerical and experimental results are shown to demonstrate the design concept.

Dome-Shaped Ellipsoidal Reflector Antenna for UHF-RFID Readers With Confined Near-Field Detection Region

This letter proposes and demonstrates the concept of ellipsoidal reflector antennas for radio frequency identification reader applications at UHF band. The antenna can be potentially integrated with environmental structures to confine the reader detection region. The energy bounding characteristics result from the dual-focus feature of an ellipsoidal reflector in its near-field region, as the feed located at one of the two foci can create a focused field distribution around the other focus. An axial energy focusing is, thus, formed to confine the energy in a restricted region (near-field beam focusing), also minimizing the interference effects outside of the targeted area. Both numerical simulations and experimental results are presented to demonstrate the feasibility of this antenna concept.

A design of waveguide integrated RF lens antenna operated at Ku-band

This paper presents a design of RF lens antenna that is integrated in a waveguide for the radiation of dual-linear polarizations. It exhibits excellent characteristics of -10dB beamwidth for its application as a feed of a reflector antenna in the digital TV reception of satellite communication. The design is validated by a numerical simulation using HFSS[1] and experimental examinations, which will be presented in the conference presentation.