Asymmetric feeding active leaky-wave antenna arrays

Abstract

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 1×2 and 1×4 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. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 18: 14–17, 1998.

Microstrip leaky‐wave antenna with beam‐patterns switchable capability

“…When the operating frequency increases, a pencil beam scans toward to the end-firing direction (z direction) in H-plane (y-z plane), and a fan beam radiates in quasi-E-plane. The pointing angle of pencil beam is determined as: ϭ 90°Ϫ arcsin (␤ z /k 0 ), where ␤ z is the phase constant of complex propagation constant k z ϭ ␤ z Ϫ j␣ z , k 0 is the wave number of free space wave [2,3]. To excite the first higher order mode in the operating region of frequency, the MLWA element should be fed asymmetrically.…”

“…Microstrip leakywave antenna (MLWA) has the advantage of simple construction, low-profiles, narrow beam width, and frequency-scanning ability. MLWA has been applied in many fields, such as cruise control and radiolocation, in the last few years [3][4][5].…”

“…It's a single-beam antenna. The single-beam MLWA has been widely theoretically studied and experimentally applied since then [2,3]. There are some researches focusing on the dual-beam MLWA [4,5].…”

“…In general, the single-channel fiber grating is much often used for sensing one physical parameter by measuring the Bragg wavelength shift. For the publications of fiber-sensing measurement [3][4][5][6], the variation of optical power in the sensing head can be used for detecting the change of external physical or chemical parameters. For a multichannel grating, the superstructure fiber Bragg grating (SFBG) with the characteristics of multireflection channels has also been used to simultaneously measure different physical parameters.…”

A novel two-beam scanning active leaky-wave antenna

“…The VCO frequencies are tuned by adjusting the varactor dc bias voltage to control the LWA two-beam scanning position. An advantage of our design is the suppression of the reflected wave coming from the open end of a finite-length leaky-wave antenna, although that can also be suppressed with a longer-length approach [4] or an array topology [8]. This two-port design can be thought to offer loads on both open ends of the antenna.…”