Woosung Lee

Beamforming Lens Antenna on a High Resistivity Silicon Wafer for 60 GHz WPAN

Wafer-scale beamforming lenses for future IEEE802.15.3c 60 GHz WPAN applications are presented. An on-wafer fabrication is of particular interest because a beamforming lens can be fabricated with sub-circuits in a single process. It means that the beamforming lens system would be compact, reliable, and cost-effective. The Rotman lens and the Rotman lens with antenna arrays were fabricated on a high-resistivity silicon (HRS) wafer in a semiconductor process, which is a preliminary research to check the feasibility of a Rotman lens for a chip scale packaging. In the case of the Rotman lens only, the efficiency is in the range from 50% to 70% depending on which beam port is excited. Assuming that the lens is coupled with ideal isotropic antennas, the synthesized beam patterns from the S-parameters shows that the beam directions are -29.3°, -15.1°, 0.2°, 15.2°, and 29.5 °, and the beam widths are 15.37°, 15.62°, 15.46°, 15.51°, and 15.63°, respectively. In the case of the Rotman lens with antenna array, the patterns were measured by using on-wafer measurement setup. It shows that the beam directions are -26.6°, -21.8°, 0°, 21.8°, and 26.6° . These results are in good agreement with the calculated results from ray-optic. Thus, it is verified that the lens antenna implemented on a wafer can be feasible for the system-in-package (SiP) and wafer-level package technologies.

Compact Two-Layer Rotman Lens-Fed Microstrip Antenna Array at 24 GHz

This paper presents a new design to realize a compact Rotman lens-fed antenna array. The lens-fed antenna has the form of two layers, which is a new approach to reducing the size of the Rotman lens. The approach is demonstrated at 24 GHz aiming for an automotive sensing radar. The lens consists of a top metal layer, a dielectric, a common ground, a dielectric, and a bottom metal layer, in sequential order. The layout of the lens body is placed on the bottom layer and the antennas are placed on the top layer. Both of them are electrically connected through slot transitions. This two-layer structure reduces not only the total size of the lens, but also the loss of the delay lines because the lines can be designed to be as short and straight as possible. The two-layer Rotman lens-fed antenna array is measured in terms of scattering parameters and beam patterns. From the scattering parameters, the power efficiencies of the beam port 1, 2, and 3 at 24 GHz are obtained as 32.3%, 48.5%, and 50.8%, respectively. The measured beam patterns show that the beam directions are -28.1°, -14.9°, 0°, 15.5°, and 28.6° and the beamwidths are 13.4°, 13.2°, 12.8°, 13.5°, and 13.0°. The measurements confirm that the compact two-layer Rotman lens has been successfully demonstrated.

UWB wide slot antenna with band-notch function

A novel UWB wide slot antenna that has both enhanced impedance bandwidth enough to cover UWB systems and band-notch function of 5 GHz WLAN band limited by IEEE 802.11a and HIPERLAN/2 is proposed. To achieve these two characteristics of wide bandwidth and partial band-notch, a fork-shaped and tapered microstrip feed line and conductor lines in the slot are used, respectively. From the results, it is observed that wide bandwidth from 3.1 to 10.6 GHz for the VSWR<2 is achieved, while 5.15 ~ 5.825 GHz is band-notched

Reconfigurable slot antenna with wide bandwidth

In this paper, a frequency reconfigurable slot antenna which has wide bandwidth is proposed. The proposed antenna, using PIN diodes, consists of two parts; wide slot and narrow slot. To enhance the bandwidth, the antenna has a wide slot, and narrow slot in which PIN diodes are applied that controls center frequency by changing the on/off state of PIN diodes. Thus, the proposed antenna can have frequency reconfigurable characteristic and wide bandwidth

Wideband antenna for mobile terminals using a coupled feeding structure

A wideband antenna which consists of a planar inverted F-antenna (PIFA) with a coupled feeding structure for wireless terminals is presented. The operating bandwidth of the proposed antenna is from 820 MHz to 3 GHz, as far as we know, this is the first antenna which covers entire bands of wireless communication applications (GSM850 / GSM900 / GPS / DCS1800 / PCS1900 / WCDMA1700 / WCDMA2100 / WiBro2350 / Bluetooth (BT) / Wi-Fi / WiMAX2500 and Long Term Evolution (LTE) 2600). Therefore, it can be used as current 2G/3G/4G services as well as GPS. In addition, the antenna has small size, 20 × 40 mm2, and can be directly printed on no-ground region of system circuit board. The overall area of Printed Circuit Board (PCB) including antenna area is 40 × 100 × 0.8 mm3. As a result, the proposed antenna is suitable for compact mobile applications and small wireless devices.

A 60 GHz Rotman lens on a silicon wafer for system-on-a-chip and system-in-package applications

As a semiconductor microfabrication process is advanced, there are needs for implementing various components on a wafer. A 60 GHz Rotman lens on a silicon wafer has been proposed for system-on-a-chip (SoC) and system-in-package (SiP) applications. The lens was fabricated on a high resistivity silicon wafer in semiconductor process. The lens has five beam ports and seven array ports. It was observed from the measurement that the phase and the amplitude of the Rotman lens are well distributed. The beam patterns were synthesized from the measured S-parameters. The beam directions are ±30° ±16°, and 0°, and the half power beam width are 15.37°, 14.68°, 14.53°, 14.68°, and 15.37°, respectively. The feasibility of the lens on a silicon wafer has been well explored.

Small RFID tag antenna with bandwidth-enhanced characteristic

In this paper, a small RFID tag antenna in UHF band which has bandwidth-enhanced characteristic is proposed. The shape of the proposed antenna is a meander antenna to reduce size, and the antenna consists of two radiators which make dual resonance in adjacent frequencies to enhance bandwidth. By adjusting length and location of each radiator, the proposed antenna can easily make dual resonance at arbitrary location on the Smith chart, which is able to make impedance matching with RFID tag chip in wide frequency range

One dimensional phase conjugating/retrodirective mirror in millimeter-wave band

As the design and fabrication of high-frequency microwave components are developed, many applications are recently proposed in millimeter-wave band. The applications are communications, imaging, sensing, and RF power delivering in which new conceptual approaches, retrodirective or phase conjugating array, have been also considered. One of emerging technologies is a passive millimeter-wave (PMMW) imaging system [1]. The key aspect of the PMMW imaging system is its penetration capability. Different from the optical imaging system, the PMMW imaging system can form images in low-visibility conditions such as night, foggy weather, clouds, and even though cloths. This characteristic is useful for many applications in both commercial and military areas.

Planar inverted F-antenna with suppressed harmonic

In this paper, a novel method to suppress harmonic component of PIFA is proposed. The spur-line is inserted between the feed and short line of PIFA and obstructs the feed line to suppress harmonic without induction of dual-band resonance. Additionally, partial ground is inserted the bottom side of radiator to improve the performance of suppression. The simulated and measured results show that the proposed method can suppress the harmonic component of PIFA without any distortion of operating band and can be used widely in many applications using PIFA.

Morphological classification system of hair regrowth patterns in alopecia areata patches: DIMT classification

Alopecia areata (AA) is an autoimmune disease causing non-scarring hair loss. In many cases, regrowth of hair can be expected either with or without treatment. In vitiligo, which has similarities in pathogenesis with AA, repigmentation patterns have been classified into 5 distinct patterns: diffuse, marginal, perifollicular, combined, and medium-spotted. This article is protected by copyright. All rights reserved.