Browsing by Author "Wu, JJ"

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A back-to-back dual-beam active microstrip leaky-wave antenna array with mode-switching capability
(2000-02-05)
Hu, CC
;
Jou, CF
;
Wu, JJ
;
Peng, ST
;
傳播研究所
An X-band two-element back-to-back coupled-oscillator-driven spatial power-combining microstrip leaky-wave antenna array is developed, which has a dual-beam radiation pattern and mode-switching capability. Two Gunn diode CPW oscillators are placed on the back side of the substrate, each driving two back-to-back microstrip leaky-wave antenna pairs in opposite directions for dual-beam operation. This active antenna array is able to produce sum and difference patterns between the in-phase and 180 degrees out-of-phase mode by controlling the bias voltages of the Gunn diodes. (C) 2000 John Wiley & Sons, Inc.
A CPW-to-Slotline active gunn diode leaky wave antenna
(1998)
Lee, SH
;
Wu, JJ
;
Peng, ST
;
Hu, CC
;
Jou, CF
A X-band coplanar waveguide (CPW) to slotline couple feeding active microstrip leaky wave antenna using Gunn-diode oscillator as source is demonstrated. The method to excite the first higher order mode of the microstrip leaky wave antenna is to put the CPW-to-slotline transition underneath the middle of the microstrip line, and the oscillator circuit and radiating element are separated by a ground plane. The measured angle of the maximum beam direction of active antenna is at 72 degrees for the active Gunn oscillator frequency of 11.218 GHz; This prototype of active leaky wave antenna feeding by Gunn diode oscillator with CPW-to-slotline structure can be easily scaled up to millimeter wave frequency region.
A Gunn-diode active leaky-wave frequency scanning antenna
(1998-01-01)
Lee, SH
;
Jou, CK
;
Lee, CP
;
Hu, CC
;
Wu, JJ
A frequency tunable active leaky-wave scanning antenna using Gunn-diode voltage control oscillator (VCO) as source is developed. The frequency tuning controlled by changing either the varactor diode de bias or the Gunn diode de bias is demonstrated. The measured scanning angle of active antenna is close to 15 degree as the Gunn VCO frequency tuned from 12.58GHz to 12.98GHz. To excite the first higher order mode of the microstrip leaky-wave antenna is fed asymmetrically. The dominant mode excitation has been successfully suppressed by adding a sequence of covered wire in the middle line of the microstrip leaky wave antenna. This is a prototype of frequency scanning antenna using two terminal device, which can be easily scaled up to millimeter wave frequency region.
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 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 formulation for complex modes of image lines
(1996)
Peng, ST
;
Wu, JJ
;
電信工程研究所
;
Institute of Communications Engineering
A Stop-or-Move Mobility model for PCS networks and its location-tracking strategies
(2003-07-21)
Tseng, YC
;
Chen, LW
;
Yang, MH
;
Wu, JJ
;
資訊工程學系
This paper considers the location-tracking problem in PCS networks. Solutions to this problem in fact highly depend on the mobility patterns of mobile subscribers [ACM DIAL-M (1999) 72]. In the literature, many works have assumed a simple random walk model, where mobile subscribers always stay in a roaming state and can move in any direction with equal probability. In this paper, we propose a new Stop-or-Move Mobility (SMM) model, which is characterized by the following features: 'transition between stop and move', 'infrequent transition', 'memory of roaming direction', and 'oblivious in different moves'. Based on this mobility model, a static and an adaptive location-tracking Scheme are developed. The schemes only need to keep very little information for each user. Analyses and simulations are provided, which show that the proposed schemes are quite prospective. (C) 2003 Elsevier Science B,V. All rights reserved.
A two-dimensional beam-scanning linear active leaky-wave antenna array
(1999-03-01)
Hu, CC
;
Jou, CF
;
Wu, JJ
;
傳播研究所
;
Institute of Communication Studies
This letter presents a new technique fur electronic two-dimensional beam scanning using a phase-shifterless linear active leaky-wave antenna array. The varactor-tuned voltage-controlled oscillators (VCO's) and coupling network are implemented in this array. The measured pattern of this 4 x 1 leaky-wave antenna array shows that the main beam can be continuously scanned from 68 degrees to 40 degrees in elevation as the frequency varied from 8.24 to 9.15 GHz. By tuning the free-running frequencies of the end elements, the main beam can be continuously scanned from -26 degrees to +10 degrees in azimuth, A maximum ERP of 667 mW is measured at 8.9 GHz for this active antenna array.
Active aperture-coupled leaky-wave antenna
(1998-11-12)
Kao, NA
;
Hu, CC
;
Wu, JJ
;
Jou, CF
;
傳播研究所
An active aperture-coupled leaky-wave antenna which is integrated with a varactor-tuned high electron mobility transistor voltage-controlled oscillator (HEMT VCO) is presented. To excite the first higher mode of the microstrip, the aperture-coupled structure is used and a sequence of covered wire is added at the centre of this antenna to suppress the dominant mode. The measured H-plane main beam can be continuously scanned 10 degrees as the HEMT VCO frequency is varied from 9.05 to 9.5GHz. This feeding structure is very suitable for active phase antenna array applications.
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 frequency-tuned beam-scanning leaky-wave antenna
(1998-01-01)
Hu, CC
;
Wu, JJ
;
Jou, CF
;
交大名義發表
;
傳播研究所
A frequency-tuned beam-scanning antenna is developed, which integrated a microstrip leaky-wave antenna with a varactor-tuned HEMT VCO as the source. The microstrip leaky-wave antenna is operated in the first higher mode. To excite the first higher mode, microstrip leaky-wave antenna is fed asymmetrically. The dominant mode excitation has been successfully suppressed by adding a sequence of covered wire in the center of the microstrip leaky-wave antenna. The HEMT oscillator frequency is controlled by tuning the varactor dc bias, and the beam scanning is demonstrated. The measured scanning angle agrees well with the prediction; it is close to 30 degrees as the VCO frequency is tuned from 8.06 to 9 GHz. (C) 1998 John Wiley & Sons, Inc.
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 aperture-coupled linear leaky-wave antenna array with 2-D dual-beam scanning capability
(2000-04-05)
Hu, CC
;
Wu, JJ
;
Jou, CF
;
傳播研究所
;
Institute of Communication Studies
An X-band four-element linear microstrip leaky-wave antenna (LWA) array wit a dual-beam radiation pattern and two-dimensional scanning capability is developed. The measured half-power beamwidths of the H-plane and quasi-E-plane radiation patterns are less than 30 degrees. By tuning the dc bias of the varactor phase shifter between the antenna elements, the main beam can be scanned in the azimuth plane from -13 degrees to +13 degrees off broadside. In the elevation plane, the beam-scanning angle is close to 20 degrees as the operating frequency is tuned form 11.58 to 12.5 GHz. (C) 2000 John Wiley & Sons, Inc.
An aperture-coupled linear microstrip leaky-wave antenna array with two-dimensional dual-beam scanning capability
(2000-06-01)
Hu, CC
;
Jou, CF
;
Wu, JJ
;
傳播研究所
;
Institute of Communication Studies
This paper describes an X-band 4 x 1 aperture-coupled series-fed electronically steerable microstrip leaky-wave antenna (LWA) array design, which has dual-beam radiation pattern and two-dimensional (2-D) beam-scanning capability. The LWA array is operated in the first higher order mode and excited by center-fed aperture coupled for dual-beam operation. The varactor-tuned phase shifters are placed between the antenna elements. The measured half-power beamwidth of the H-plane and quasi-E-plane radiation patterns are less than 30 degrees. By tuning the reverse de bias of the varactor diodes, the main beam can be scanned in azimuth plane from -13 degrees to +13 degrees off broadside. In the elevation plane, the beam-scanning angle is close to 20 degrees as the operating frequency tuned from 11.58-12.5 GHz. Taking into account each phase-shifter insertion loss and phase progression, the measured results compared closely with the theoretical prediction, The proposed antenna array is suitable for wireless communication and collision warning radar systems.
An asymmetric feeding X-band active frequency-scanning leaky-wave antenna
(1997-09-01)
Hu, CC
;
Wu, JJ
;
Jou, CF
;
交大名義發表
;
傳播研究所
An asymmetric feeding X-band active leaky-wave antennas is developed, to excite the first high order mode of the microstrip leaky wave antenna. One is the asymmetric feeding leaky-wave antenna which integrated with a HEMT oscillator, and the other is the frequency-tuned leaky-wave antenna which integrated with a varactor-tuned HEMT VCO. The microstrip leaky-wave antenna is operated in the first higher mode. To excite the first higher mode, the microstrip leaky-wave antenna is fed asymmetrically. The dominant mode excitation has been successfully suppressed by adding a sequence of covered wire in the center of the microstrip leaky wave antenna. The design of these active leaky-wave antennas is discussed and the beam scanning phenomena of the antenna is presented. The HEMT oscillator frequency is controlled by tuning the varactor DC bias and the beam scanning is demonstrated. The measured scanning angle agree with prediction, it is close to 30 degrees as the VCO frequency tuned from 8.06 GHz to 9GHz.
An asymmetric feeding X-band active frequency-scanning leaky-wave antenna
(1997-09-01)
Hu, CC
;
Wu, JJ
;
Jou, CF
;
電信工程研究所
;
Institute of Communications Engineering
An asymmetric feeding X-band active leaky-wave antennas is developed, to excite the first high order mode of the microstrip leaky wave antenna. One is the asymmetric feeding leaky-wave antenna which integrated with a HEMT oscillator, and the other is the frequency-tuned leaky-wave antenna which integrated with a varactor-tuned HEMT VCO. The microstrip leaky-wave antenna is operated in the first higher mode. To excite the first higher mode, the microstrip leaky-wave antenna is fed asymmetrically. The dominant mode excitation has been successfully suppressed by adding a sequence of covered wire in the center of the microstrip leaky wave antenna. The design of these active leaky-wave antennas is discussed and the beam scanning phenomena of the antenna is presented. The HEMT oscillator frequency is controlled by tuning the varactor DC bias and the beam scanning is demonstrated. The measured scanning angle agree with prediction, it is close to 30 degrees as the VCO frequency tuned from 8.06 GHz to 9GHz.