Masaki Nishio

A triangular loop antenna mounted adjacent to a lossy Si substrate for millimeter-wave wireless PAN

Millimeter-wave wireless communication is expected to be used for wireless personal area network (WPAN) for which a bit rate of 1Gbps or more is needed. Our goal is the development of an antenna suited to a WPAN terminal. Since a small, low-cost antenna with high radiation efficiency and a high gain in a wide- angle range is required for WPAN, the beam scan becomes unnecessary. In this paper, we propose a novel triangular loop antenna with a simple structure which has a feed point on to a semiconductor substrate.

A Study of Wideband Built-in Antenna using RF-MEMS Variable Capacitor for Digital Terrestrial Broadcasting

In this paper, the wideband properties of a proposed antenna with the low-voltage-actuated MEMS variable capacitor is shown by calculation and measurement. First the mechanism of the wideband properties of the proposed antenna due to the use of a dual resonant mode is clarified. Then, applying the MEMS variable capacitor, the properties of the proposed antenna are calculated and measured

Piezoelectric MEMS Variable Capacitor for a UHF Band Tunable Built-in Antenna

A UHF band tunable built-in antenna is realized using piezoelectric MEMS variable capacitors. The variable capacitor, which is driven by a piezoelectric actuator, has a tuning ratio of 11 with control voltage ranging from 0 to 8 V and quality factor of more than 37 at 650 MHz. The built-in antenna, which is an inverted-F antenna, is mounted at the top of an upper PCB board of a clamshell mobile phone, and the antenna element has a meander shape for a built-in structure. In the tunable built-in antenna, the variable capacitor is connected to one point of the meander structure of the built-in antenna. The antenna covers a frequency from 510 to 800 MHz with an efficiency of more than -3.5 dB, or the relative bandwidth of 44% by changing the value of the variable capacitor.

Low profile double resonance frequency tunable antenna using RF MEMS variable capacitor for digital terrestrial broadcasting reception

It is difficult to realize the built-in antenna for wideband systems, because a frequency bandwidth of the low profile antenna is narrow. A frequency tunable antenna is a technique for wideband characteristics. In this paper a low profile double resonance frequency tunable antenna using MEMS variable capacitors is presented. It has high efficiency over a wide frequency band. Through both resonant portions from 465 to 665 MHz, the efficiency of more than −4 dB and the VSWR of less than 3 are observed in the measurement using the variable capacitor of 0.4–0.9 pF.

Dual-band bent-folded-monopole antenna

Recently, frequency tunable antennas with multi-band operation capability are proposed to achieve small size and high performance at the same time [1]. For example, RF switches are used in [2] to change grounding and/or feed points to shift antenna current distributions. Moreover, MEMS (Micro Electro Mechanical Systems) variable capacitor is placed on the top of an antenna element to change its electrical length to cover the wide operation band of the digital terrestrial broadcasting service [3]. These antenna structures will be effective for wideband operation, but recent increase of antenna built in mobile terminals requires smaller antennas with keeping high performance.