Search

A small zero-order resonant antenna based on the composite right-left-handed (CRLH) principle is designed and fabricated without metallic vias at 30 GHz to have patch-like radiation. The mirror images of two CRLH structures are connected to design the antenna without via holes. The equivalent circuit, parameter extraction, and dispersion diagram are studied to analyze the characteristics of the CRLH antenna. The antenna was fabricated and experimentally verified. The measured realized gain of the antenna is 5.35 dBi at 30 GHz. The designed antenna is free of spurious resonance over a band width of 10 GHz. A passive beamforming array is designed using the proposed CRLH antenna and the Butler matrix. A substrate integrated waveguide is used to implement the Butler matrix. The CRLH antennas are connected to four outputs of a 4 × 4 Butler matrix. The scanning angles are 12 ∘ , − 68 ∘ , 64 ∘ , and − 11 ∘ for excitations from port 1 to port 4 of the 4 × 4 Butler matrix feeding the CRLH antenna. [ABSTRACT FROM AUTHOR]

A compact and circularly polarized planar antenna is presented in this communication based on a quarter-mode substrate integrated waveguide sub-array. The operating principle and design guidelines of the proposed antenna are discussed with the aid of an isosceles right triangular cavity with two magnetic side walls and one electric side wall. The mode solutions are determined and the resonant frequencies of the triangular cavity are calculated. The designed antenna is fabricated and its radiation characteristics are measured. Measured results are in good agreement with predicted ones. It is demonstrated that the proposed structure is a simple and compact candidate of high-performance circularly polarized antenna. [ABSTRACT FROM PUBLISHER]

Compact, asymmetric\symmetric-slotted\slit-microstrip patch antennas on reactive impedance surface (RIS) are proposed and studied for circularly polarized (CP) radiation. The antennas consist of a slotted-slit-microstrip patch on a RIS substrate. The CP radiation with compact size is achieved by asymmetric\symmetric-slot-slit cut along the orthogonal\diagonal directions of the patch radiator. The asymmetric\symmetric-slotted\slit microstrip patches on the RIS structure are used for further miniaturization of the antenna with improvement in CP radiation. The measured results of the compact asymmetric-cross slotted square patch antenna are 1.6% (2.51–2.55 GHz) for 3-dB axial ratio bandwidth, 5.2% (2.47–2.60 GHz) for 10-dB return loss bandwidth, and 3.41 dBic for gain over 3-dB axial ratio bandwidth. The overall antenna volume is 0.292\lambdao\times 0.292\lambdao\times 0.0308\lambdao on a low cost FR4 substrate at 2.5 GHz. [ABSTRACT FROM PUBLISHER]

The single-feed, circularly polarized microstrip antennas (CPMAs) based on the slotted-ground plane are investigated for radiofrequency identification readers.The conventional CPMA with truncated corners is also studied to compare with the proposed CPMA's performances. In the proposed designs, four square slots with asymmetrical configuration are etched in the diagonal directions on the ground plane of the antenna to achieve circularly polarized radiation. The proposed CPMAs are designed with low-cost FR4 substrate and RO4003C substrate and their performances are compared. The antenna bandwidth is also studied on thin and thick dielectric substrates. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2304-2309, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27075 [ABSTRACT FROM AUTHOR]

A double periodic composite right/left-handed ( DP-CRLH ) substrate integrated waveguide (SIW) is proposed based on the transmission line theory. A new leaky-wave radiation is observed at low frequency below the left-handed passband in addition to the composite right/left-handed property. First, the equivalent circuit of the proposed structure is analyzed, and dispersion characteristics are obtained including the expression for the cutoff frequencies. It is noted that transmission lines double periodically loaded with either alternate capacitances, or alternate inductances will contribute the new leaky-wave behavior. Next, SIW implementation of a DP-CRLH transmission line is designed and illustrated with simulated and experimentally demonstrated results. The electric field distribution plots are extracted from a full-wave simulation tool and exhibit the forward and backward wave propagation in the new leaky-wave region and the typical left-handed region, respectively. Finally, a compact leaky-wave antenna based on the DP-CRLH SIW is designed, and the radiation characteristics are tested and demonstrated to exhibit forward radiation at the new leaky-wave region from 5.2 to 5.8 GHz (covering IEEE 802.11a band) and frequency scanning from backward to forward directions in the left-handed and conventional right-handed region from 12.6 to 17.8 GHz. [ABSTRACT FROM AUTHOR]