Browsing by Author "Wang, CJ"

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A beam-forming technique for leaky-wave antennas
(2001-01-20)
Chen, IY
;
Wang, CJ
;
Liu, SJ
;
Jou, CF
;
傳播研究所
A beam-forming technique for leaky-wave antennas (LWAs) which can switch electronically in three different radiation patterns is developed in this letter. A simple two-terminal feeding microstrip-line LWA works as a radiating element. By varying the phase of the two injection signals from 0 to 180 degrees, the emitting power from the LWA can produce three different radiation modes: the normal mode (one sharp beam), the difference mode (Delta), and the sum mode (Sigma). The antenna displays large-bandwidth characteristics, and can be useful near crossroads for collision avoidance or in the radio location of vehicles. (C) 2001 John Wiley & Sons, Inc.
A dual-beam asymmetrically scanning leaky-wave antenna by utilizing a HEMT resistive upconverter
(2001-12-01)
Wang, CJ
;
Sheu, YH
;
Jou, CF
;
電信工程研究所
;
Institute of Communications Engineering
A dual-beam asymmetrical scanning microstrip leaky-wave antenna (LWA) has been demonstrated in this paper. A HEMT resistive upconverter output is connected to one terminal of the LWA, and a local oscillator (LO) signal is connected to the other terminal. In this experiment, we set the LO frequency at 9.5 GHz so that the right beam is fixed at 48degrees. By changing the IF frequency from 0.7 GHz to 1.5 GHz, the module of the LWA can steer the left main beam of the far-field pattern from 136degrees to 158degrees (the total scanning angle of 22degrees). Comparisons between the measured and theoretical results indicate that the design can achieve the asymmetrically scanning capability and agree well over the tuning bandwidth of 0.8 GHz.
A new two-terminal feeding active leaky-wave antenna
(1998-11-01)
Wang, CJ
;
Jou, CF
;
Wu, JJ
;
電信工程研究所
;
Institute of Communications Engineering
A new two-terminal feeding active-integrated leaky-wave antenna design is demonstrated. The S-band microstrip two-terminal feeding leaky-wave antenna is integrated with an active high-electron mobility transistor (HEMT) oscillator to produce a two-beam radiation pattern, The antenna is fed asymmetriclly at both sides to excite the first higher order mode, This configuration, as compared to a single-terminal feeding leaky-wave antenna, has the advantage of the multidirection and the reduction of the reflected wave caused by the open end of the radiating element. Measured results show that the radiation directions of two beams are approximately at 34 degrees and 140 degrees, the effectively isotropic radiated power (EIRP) is close to 17.5 dBm, and the return Loss is almost less than -10 dB between 9 and 11.5 GHz.
A new two-terminal feeding active leaky-wave antenna
(1998-11-01)
Wang, CJ
;
Jou, CF
;
Wu, JJ
;
傳播研究所
;
Institute of Communication Studies
A new two-terminal feeding active-integrated leaky-wave antenna design is demonstrated. The S-band microstrip two-terminal feeding leaky-wave antenna is integrated with an active high-electron mobility transistor (HEMT) oscillator to produce a two-beam radiation pattern, The antenna is fed asymmetriclly at both sides to excite the first higher order mode, This configuration, as compared to a single-terminal feeding leaky-wave antenna, has the advantage of the multidirection and the reduction of the reflected wave caused by the open end of the radiating element. Measured results show that the radiation directions of two beams are approximately at 34 degrees and 140 degrees, the effectively isotropic radiated power (EIRP) is close to 17.5 dBm, and the return Loss is almost less than -10 dB between 9 and 11.5 GHz.
A novel method for short leaky-wave antennas to suppress the reflected wave
(2003-01-20)
Wang, CJ
;
Guan, HL
;
Jou, CF
;
傳播研究所
;
Institute of Communication Studies
A method to suppress the back lobe of a short leaky-wave antenna (LWA) by using an aperture-fed patch antenna on the backside is demonstrated in this paper. The aperture-fed patch antenna is connected to the open end of the LWA. This design offers another radiation path of the reflected wave and creates another radiation pattern on the back plane of the substrate. Experimental results show that the suppression of the reflected wave can be 10 dB at 10.0 GHz with an LWA length of 6 cm (2 wavelengths). Compared to the conventional design, this novel structure can radiate as efficiently as LWA at a length a wavelengths. The two radiation patterns on different planes have great potential in many applications and can provide more flexibility to traditional designs. (C) 2003 Wiley Periodicals, Inc.
A novel two-beam scanning active leaky-wave antenna
(1999-08-01)
Wang, CJ
;
Jou, CF
;
Wu, JJ
;
傳播研究所
;
Institute of Communication Studies
A novel two-beam scanning active leaky-wave antenna (LWA) has been developed, This LWA with a two-terminal feeding microstrip line structure is integrated with a varactor-tuned X-band high-electron mobility transistor (HEMT) voltage-controlled oscillator (VCO). The signal of the VCO is injected via a T-divider into the radiating element. To excite the first higher order mode, the designed antenna is fed asymmetrically at both ends of the microstrip line. Compared with single-terminal feeding leaky-wave antennas, this configuration offers the advantages of dual-direction and suppression of the reflected wave caused by the open end of the radiating element. The scanning angle is steered over a range of 24-46 degrees for the right beam and 128-150 degrees for the left beam. The Effective isotropic radiated power (EIRP) is calculated to be 17.5 and 16.67 dBm at 10.4 GHz, respectively. The measured return loss S-11 is less than -10 dB in the range of 9-11.5 GHz, The transmission coefficient S-21 indicates that the power radiates into the space.
A simple chemical etching technique for reproducible fabrication of robust scanning near-field fiber probes
(1998-02-01)
Chuang, YH
;
Sun, KG
;
Wang, CJ
;
Huang, JY
;
Pan, CL
A two-step chemical etching procedure has been developed for fabricating probes used by scanning near-field optical microscopy. These probes have two tapered regions which can be reproducibly constructed with a wide range of cone angles. The shape of the probe allows it to be used over sample surfaces with deep and narrow regions. Furthermore, our method can be applied to silica glass fibers which are commercially available. To demonstrate, we used these tips to acquire the near-field optical image of a thin layer of polystyrene spheres. Intensity interference patterns were observed. The demonstrated in-plane resolution was estimated to be about 250 nm. This is mainly limited by the diameter of the metal-coated tip. The transmission efficiency of the tip is better than 10(-4). (C) 1998 American Institute of Physics.
Active asymmetrically feeding dual-beam leaky-wave antenna
(1998)
Wang, CJ
;
Jou, CF
;
Wu, JJ
;
Peng, ST
;
傳播研究所
An active-integrated dual-beam scanning leaky-wave antenna design is developed in this paper. A varactor-tuned oscillator HEMT VCO, an active source, integrates with an X-band two-terminal asymmetrically feeding microstrip leaky-wave antenna on the same plane. This approach creates a dual-beam radiation pattern and has the advantages of multi-direction and no reflected wave caused by the open end of the radiating element, as compared to a traditionally single-terminal feeding leaky-wave antenna. Measured results on the experimental antenna show that the total scanning angle of two beams of this antenna configuration is approximately 44 degrees The maximum Effective Isotropic Radiated Power (EIRP) are. close to 17.5 dBm for the right beam and 16.67 dBm for the left beam at 10.4 GHz,and the power difference between the two beams is less than 1 dB.
Active dual-beam aperture-coupled leaky-wave antenna
(1999-11-11)
Wang, CJ
;
Kao, NA
;
Jou, CF
;
Wu, JJ
;
傳播研究所
An active aperture-coupled leaky-wave antenna (LWA) with excellent dual-beam scanning capability is presented. An X-band varactor-tuned HEMT VCO is integrated on the other plane through an aperture with the LWA. This antenna has the advantages of multi-functionability, interference shielding, and a scanning main beam. The measured main beam in the elevation plane can be continuously scanned for 20 degrees for each beam as the HEMT VCO frequency is varied from 8.97 to 9.5 GHz. An effective isotropic radiation power of 18.89 dBm for the right beam and 19.06 dBm for the left beam is achieved.
Active frequency-tune beam-scanning leaky-wave antenna arrays
(1998-02-01)
Wang, CJ
;
Wu, JJ
;
Jou, CF
;
電信工程研究所
;
Institute of Communications Engineering
X-band active beam-scanning leaky-wave antenna arrays, including 1 X 1, 1 X 2 and 1 X 4 prototypes, have been demonstrated. These antennas integrated one or several microstrip leaky-wave antenna elements with a single varactor-tuned HEMT VCO as an active source. Measured results on experimental antennas indicate that the beam scanning angle of the 1 X 1 antenna close to 40(0) can be achieved and the scanning range of 1 X 2 and 1 X 4 antenna arrays are both close to 32(0), Furthermore, reflected wave due to the open end of each leaky-wave antenna element has been suppressed by the symmetric configuration of this antenna array and the antenna efficiency increases. When comparing with the measured radiation pattern of the single element antenna, we found that the 1 X 2 and 1 X 4 antenna arrays can effectively suppress the reflected power by more than 5.5 dB and 10.5 dB, respectively, at 10.2GHz. The power gain are more than 2 dB and 3.16 dB higher than the single element antenna with a measured EIRP of 18.67 dBm.
Active frequency-tune beam-scanning leaky-wave antenna arrays
(1998-02-01)
Wang, CJ
;
Wu, JJ
;
Jou, CF
;
傳播研究所
;
Institute of Communication Studies
X-band active beam-scanning leaky-wave antenna arrays, including 1 X 1, 1 X 2 and 1 X 4 prototypes, have been demonstrated. These antennas integrated one or several microstrip leaky-wave antenna elements with a single varactor-tuned HEMT VCO as an active source. Measured results on experimental antennas indicate that the beam scanning angle of the 1 X 1 antenna close to 40(0) can be achieved and the scanning range of 1 X 2 and 1 X 4 antenna arrays are both close to 32(0), Furthermore, reflected wave due to the open end of each leaky-wave antenna element has been suppressed by the symmetric configuration of this antenna array and the antenna efficiency increases. When comparing with the measured radiation pattern of the single element antenna, we found that the 1 X 2 and 1 X 4 antenna arrays can effectively suppress the reflected power by more than 5.5 dB and 10.5 dB, respectively, at 10.2GHz. The power gain are more than 2 dB and 3.16 dB higher than the single element antenna with a measured EIRP of 18.67 dBm.
An active microstrip antenna for satellite communication
(2000)
Wang, CJ
;
Jou, CF
;
Wu, JJ
;
Peng, ST
;
傳播研究所
An active microstrip antenna for the satellite communication is developed in this paper. A varactor-tuned oscillator HEMT VCO, an active source, integrates with an X-band two-terminal asymmetrically feeding microstrip leaky-wave antenna on the same plane. This approach creates a dual-beam radiation pattern and has the advantages of multi-direction and suppression of the reflected wave caused by the open end of the radiating element, as compared to a traditionally single-terminal feeding leaky-wave antenna. Measured results on the experimental antenna show that the total scanning angle of two beams of this antenna configuration is approximately 44 degrees. The maximum Effective Isotropic Radiated Power (EIRP) are close to 17.5 dBm for the right beam and 16.67 dBm for the left beam at 10.4 GHz, and the power difference between the two beams is less than 1 dB. An asymmetrically beam-scanning leaky-wave antenna is also shown in this presentation.
An improved interface characterization technique for a full-range profiling of oxide damage in ultra-thin gate oxide CMOS devices
(2003)
Chen, SJ
;
Lin, TC
;
Lo, DK
;
Yang, JJ
;
Chung, SS
In this paper, an improved gate-diode technique has been developed for the interface characterization on both n- and p-MOSFET's with gate oxide in the direct tunneling regime. This method has been demonstrated successfully for measuring oxide damage in all of the channel, space-charge (or junction), and drain extension regions in 20Angstrom ultra-thin gate oxide devices. As an application of the present method, the lateral profile of localized oxide damage due to Negative Bias Temperature Instability (NBTI) or Hot Carrier (HC) effect has been demonstrated. It provides us an understanding of the correlation between the device degradation and various stress-induced oxide damage in CMOS devices.
Asymmetric feeding active leaky-wave antenna arrays
(1998-05-01)
Wang, CJ
;
Wu, JJ
;
Hu, CC
;
Jou, CF
;
傳播研究所
The active leaky-wave antenna arrays have been demonstrated, which integrate several microstrip leaky-wave antenna elements with a single HEMT oscillator as an active source at 10.2 GHz. To excite the first higher order mode, the leaky-wave antenna is fed asymmetrically. The reflected wave due to the open end of each leaky-wave antenna element has been suppressed by the symmetric configuration of this antenna array. When comparing with the measured radiation pattern of the single-element antenna, we found that 1 x 2 and 1 x 4 antenna arrays can effectively suppress the reflected power by more than 5.5 and 10.5 dB, respectively. Furthermore, the power gains are more than 2 and 3.16 dB higher than the single-element antenna with a measured EIRP of 18.67 dBm. (C) 1998 John Wiley & Sons, Inc.
Beam-switchable scanning leaky-wave antenna
(2000-03-30)
Wang, CJ
;
Shih, YC
;
Jou, CF
;
傳播研究所
;
Institute of Communication Studies
A beam-switchable scanning leaky-wave antenna (LWA) has been developed. This LWA with a two-terminal feeding microstrip, line structure is integrated with a single port double throw (SPDT) snitch as a control circuit. In dual-beam mode, the scanning angle is steered over a range of 36-64 degrees for the right-hand beam and 144 -116 degrees for the left-hand beam. In one-beam made, the scanning angle is measured over 20 degrees for the right-hand beam. The measured result shows that we can change from the, one-beam mode to the dual-beam mode electronically by controlling the on/off status of an SPDT switch, in contrast to the case For traditional leaky wave antennas.
Characterization of porous silicate for ultra-low k dielectric application
(2002-07-01)
Liu, PT
;
Chang, TC
;
Hsu, KC
;
Tseng, TY
;
Chen, LM
Thermal stability of a porous low-k film is a critical issue for application consideration in the back-end-of-line. In this study, thermal stability of the porous silicate has been investigated by changing the thermal processing temperatures. Experimental results have shown that the dielectric constant of the porous silicate still remains below 2.0 after thermal processing at 500 degreesC for I h. A series of material analysis techniques and electrical characteristics have been used to verify the physical and chemical characteristics of the porous silicate film. (C) 2002 Elsevier Science B.V. All rights reserved.
Compact microstrip meander antenna
(1999-09-20)
Wang, CJ
;
Jou, CF
;
傳播研究所
;
Institute of Communication Studies
An electrically small microstrip meander antenna incorporating the folded technology is fabricated and experimental results ale presented in this paper. This antenna has the advantages of compact size, ease of manufacturing, broad bandwidth, and multiband characteristics. Different-feed and different-length antennas are tested. Techniques to reduce the antenna size are presented, and performance trends are established. The measured results show that the variation of the return loss can be easily tuned by changing the feeding points and the microstrip-line length. The maximum measured bandwidth is approximately 770 MHz (12.6% operational bandwidth around 6.115 GHz) when the middle feeding point is chosen. (C) 1999 John Wiley & Sons, Inc.
Coplanar waveguide to coplanar strips fed active leaky-wave antenna
(1998-01-01)
Hu, CC
;
Jou, CF
;
Wang, CJ
;
Lee, SH
;
Wu, JJ
A new active coplanar waveguide (CPW) to coplanar strips (CPS) fed microstrip leaky-wave antenna is developed, which integrated with a Gunn diode as active source. The CPW-CPS balun is used to excite the first higher order mode of the microstrip leaky-wave antenna. The active leaky-wave antenna has maximum EIRP of 20.4 dBm at 9.759 GHz. The Gunn oscillator frequency is controlled by tuning the Gunn DC bias and the beam scanning is demonstrated. The measured scanning angle agrees with the prediction, it is close to 12 degrees as the oscillator frequency tuned from 9.84 GHz to 9.61 GHz. The coplanar structure allow easy integration of many solid-state devices. It is suitable for monolithic power combining and millimeter wave applications.
Coplanar waveguide to coplanar strips-fed active leaky-wave antenna
(1998-12-05)
Hu, CC
;
Jou, CF
;
Wang, CJ
;
Lee, SH
;
Wu, JJ
A new active coplanar waveguide (CPW) to coplanar ships (CPS)-fed microstrip leaky-wave antenna is developed, which is integrated with a Gunn diode as an active source. The CPW-CPS balun is used to excite the first higher order mode of the microstrip leaky-wave antenna. The active leaky-wave antenna has a maximum EIRP of 20.4 dBm at 9.759 GHz. The Gunn oscillator frequency is controlled by tuning the Gunn de bias, and the beam scanning is demonstrated. The measured scanning angle agrees with the prediction; it is close to 12 degrees as the oscillator frequency is tuned from 9.84 to 9.61 GHz. The coplanar structure allows easy integration of many solid-state devices. It is suitable for monolithic power combining ann millimeter-wave applications. (C) 1998 John Wiley & Sons, Inc.
Coplanar waveguide to coplanar strips-fed active leaky-wave antenna
(1998-12-05)
Hu, CC
;
Jou, CF
;
Wang, CJ
;
Lee, SH
;
Wu, JJ
A new active coplanar waveguide (CPW) to coplanar ships (CPS)-fed microstrip leaky-wave antenna is developed, which is integrated with a Gunn diode as an active source. The CPW-CPS balun is used to excite the first higher order mode of the microstrip leaky-wave antenna. The active leaky-wave antenna has a maximum EIRP of 20.4 dBm at 9.759 GHz. The Gunn oscillator frequency is controlled by tuning the Gunn de bias, and the beam scanning is demonstrated. The measured scanning angle agrees with the prediction; it is close to 12 degrees as the oscillator frequency is tuned from 9.84 to 9.61 GHz. The coplanar structure allows easy integration of many solid-state devices. It is suitable for monolithic power combining ann millimeter-wave applications. (C) 1998 John Wiley & Sons, Inc.