A novel two-beam scanning active leaky-wave antenna

Abstract

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 varactortuned X-band high-electron mobility transistor (HEMT) voltagecontrolled 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 singleterminal 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 for the right beam and 128-150 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 S11 is less than 010 dB in the range of 9-11.5 GHz. The transmission coefficient S21 indicates that the power radiates into the space.

Space Leaky Waves Propagating along a Pair of CRLH SIW Lines

“…4. Here, the field distribution calculated by (7) and (8) shows that a single beam at 9.2 GHz can be acquired only when  = 180°. The aim is to get one beam that is narrower than the two beams at other frequencies.…”

“…In recent years, leakage of energy from SIW has been widely studied for its outstanding advantages related to the continuous beam steering of the leaky field distribution. Several works were focused on the design of dual-beam leaky wave antennas [5][6][7][8]. They are preferred for both their low profiles and loss and also mainly for their scanning flexibility especially for the systems that require multiple coverage of spaces.…”

Analysis and design of hybrid leaky-wave antennas loaded with frequency selective surfaces

“…In particular, a broadside pencil beam is achieved when two beams, each one pointing slightly above broadside, combine to form one broadside beam. This effect occurs at frequencies which satisfy ; particularly, maximum directivity at broadside is achieved at the so called splitting condition Good explanation, discussion and applications of this condition can be found in [Ip 1990], [Chien- Jen 1999], [Yamamoto 1999], ], [Sutinjo 2008] and . For greater frequencies, the previous two beams split, and the radiation pattern takes the shape of a conical beam.…”

“…In recent years, it has been proven that broadside radiation is no longer a limitation to leaky wave antennas (LWAs), remarkable examples can be found in [Ip 1990], [Guglielmi 1993], [Chien- Jen 1999], [Caloz 2005], and ]. Particularly, interesting results have been lately published in order to achieve this feature in 1D LWAs.…”

“…In the case of using composite right-left-handed transmission lines, is the n=0 SH the responsible for the radiation [Caloz 2005]. Broadside radiation from homogeneous 1D LWAs can also be produced by the n=0 SH by satisfying the splitting condition in a symmetrically fed configuration [Ip 1990], ], [Chien- Jen 1999]. These papers show leaky-mode frequency results regarding the optimization of the splitting condition [Sutinjo 2008], the radiated power at broadside, -3dB beamwidth (Δθ)… 1D LWAs are commonly fed at one end, and therefore are based in the propagation of leaky-waves in a single direction , [Balanis 1982], [Lampariello 1985]...…”