Showing papers on "Front-to-back ratio published in 2009"

Planar Substrate Integrated Waveguide Cavity-Backed Antenna

Abstract: A new cavity-backed antenna compatible with planar technology is designed, manufactured, and measured. The original design consists of a slotted cavity fed by a microstrip line. This allows the implementation of the feeding line and the cavity on a single substrate, compatible with a standard printed circuit board (PCB) or low-temperature cofired ceramic (LTCC) process. The idea is to combine specific slot patterns on the cavity back face such as meandered and edge slots. An example is presented, and the measurements show minimum 10-dB return loss bandwidth of 1.32%, 8.5 dBi gain, and 21 dB front-to-back ratio. The combination of volume cavity, planar feeding, and antenna layout, leads to light weight, easy fabrication, and easy integration with planar circuits.

Performance of a Novel $\Psi$ -Shape Microstrip Patch Antenna With Wide Bandwidth

Abstract: In this letter, a novel Psi-shape microstrip patch antenna that provides wide-impedance bandwidth performance in addition to the acceptable radiation patterns is presented. The substrate is a foam material, and for ease of fabrication, the patch is etched on a thin dielectric layer, which is placed over the foam and fed by a coaxial probe. The simulated and measured 2:1 VSWR impedance bandwidths are 55% and 54%, respectively. The measured and simulated radiation patterns are in acceptable agreement as well. The measured front-to-back (F/B) ratio is better than 20 dB throughout the frequency band.

Switched Beam Antenna Based on RF MEMS SPDT Switch on Quartz Substrate

Abstract: This letter demonstrates a 20-GHz radio frequency microelectromechanical system (RF MEMS)-based electrically switchable antenna on a quartz substrate Two quasi-Yagi antenna elements are monolithically integrated with a single-pole double-throw (SPDT) MEMS switch router network on a 21 mm times 8 mm chip Electrical beam steering between two opposite directions is achieved using capacitive MEMS SPDT switches in the router Port impedance and radiation patterns are studied numerically and experimentally Measured results show that the switched beam antenna features a 27% impedance bandwidth (S11 = -10 dB), a gain of 46 dBi, and a front-to-back ratio of 14 dB at 20 GHz when the control voltage is applied to one of the switch pairs of the SPDT switch

Wideband and low sidelobe linear series fed yagi-like antenna array

Abstract: In this paper, a linear series fed Yagi-like antenna array is introduced leading to an end-flre fan beam with low sidelobe level, SLL, high front to back ratio, F/B, and wide impedance bandwidth. The array can provide i29dB SLL at centre frequency of 16.26GHz, i20dB SLL bandwidth of 7.5%, 23dB F/B and 10.6% impedance bandwidth. Further improvement in SLL can be achieved by extending narrow strips from the flnite ground plane of the antenna structure leading to some i32dB SLL at centre frequency and a i20dB SLL bandwidth of 8.7%. To verify the accuracy of the simulation results, both of the arrays are fabricated and tested. Finally, to show the applicability of the proposed design, the linear end-flre array of the above are stacked on top of each other and simulation results for a 2-D phased array are provided.

Front-to-back ratio improvement of a microstrip patch antenna using an isolated soft surface structure

Abstract: A microstrip patch antenna fabricated on a substrate, shows significant performance degradation by surface waves. Particularly when the patch antenna is printed on high dielectric substrates or thick substrate, its front-to-back ratio is considerably affected. Various solutions for the surface wave suppression such as photonic bandgap (PBG), electromagnetic bandgap (EBG), micromachining technology and complex artificial soft surfaces, which requires considerable area to form a bandgap structure. In microstrip patch antenna design, the size of ground plane is limited. To solve this problem, we propose new isolated soft surfaces structure which does not share the ground plane of a patch. By removing the ground plane edges of the patch and forming soft surfaces within the bare substrate, the front-to-back ratio of a patch antenna significantly improved. A numerical investigation is presented for a patch antenna surrounded by the proposed new soft surface structure and the effectiveness of the soft surface in terms of front-to back ratio improvement is verified by its implementation. It is shown that the broadside gain of a patch antenna can be decreased by about 1 dBi while the backside level can be increased by about 11 dBi. As a result, the improvement for the front-to-back ratio of a patch antenna can be increased to about 10 dB through the use of the proposed new soft surface structure.

Low sidelobe wideband series fed double dipole microstrip antenna array

Abstract: A linear endfire wideband series fed double-dipole antenna array with low sidelobe level, SLL, and high front to back ratio, F/B, is proposed. The array can provide -27dB SLL at centre frequency of 16.26GHz, 20dB SLL bandwidth of 9.2%, 22dB F/B and 14.6% impedance bandwidth. By extending, in between the array elements, comb like linear tapered narrow strips from the finite ground plane of the structure, SLL of the basic array improves to -32dB, the 20dB SLL bandwidth become 12.1% while the F/B and impedance bandwidth remains the same as before. To verify the accuracy of the simulation results, both of the arrays are fabricated and tested.

Dual-Band Coplanar-Waveguide-Fed Slot-Coupled Rectangular Dielectric Resonator Antenna

Abstract: Dual band antennas are important in communication systems which operate in more than one frequency band. This paper presents a new dual band coplanar waveguide- fed- slot coupled rectangular dielectric resonator antenna operating at the two frequency bands centered at 5.4 and 6.8 GHz. The use of DR allows for unidirectional radiation with a front to back ratio of more than 10 dB. The designed antenna is linearly polarized with a cross polarization level more than 26 dB lower than the co-polarization level.

Design of Compact Multiband EBG and Effect on Antenna Performance

Abstract: This paper presents the design of Electromagnetic Bandgap (EBG) structure using fractals geometry and its effect on antenna performance. The EBG structure has been designed on substrate єr = 4.3 and thickness h = 1.53 mm. The 1 st iterative EBG structure offers the surface wave attenuation around 20 dB down from 2.94 GHz to 4.58 GHz corresponds to 43.62% bandwidth. The experimental results of 2 nd iterative EBG structure revealed the surface wave attenuation in two bands from 2.45 to 3.36GHz and 8.52 to 11.02 GHz respectively. The surface wave suppression bandwidth for both the bands is 31.325% and 25.59 % respectively. The antenna design with the proposed EBG exhibits improvement in the bandwidth by 3.64%, gain by 3.2 dB and front to back ratio by 15.36 dB in comparison of antenna without EBG. In this paper, an electromagnetic band gap structure design based on fractal geometry is proposed. The proposed design offers the multiple bands and wider bandwidth attenuation in the stopband. This design based on fractal geometry provides the compact EBG structure. The simulated and experimental results have been found in close agreement. The improvement in the antenna performance has also been demonstrated using EBG structure.

Metal loaded miniaturized CPW fed DRA

Abstract: Recently, there has been an increased interest in the realization of miniaturized and high capacity transceiver systems. The dielectric resonator antenna ( DRA ) has been an ideal candidate for low-loss and broadband microwave and millimeter wave applications. The coplanar waveguide ( CPW ) feed has been proposed as an efficient feed topology to the DRA due to its low loss, dispersion, ease of active integration and uniplanar configuration. This paper presents a novel, high gain and miniaturized rectangular dielectric resonator antenna using a metallic slab as a loading element, integrated with the CPW feed. The rectangular DRA is fed with a CPW (Capacitive type) feed to ensure efficient coupling. The unloaded and loaded DRA resonance frequencies are 4.55 GHz and 3.80 GHz respectively, achieving a 16.48% reduction in resonance frequency. The gain of the unloaded and the loaded DRAs are 6.34 dBi and 6.95 dBi respectively. As a result, a 8.77% increase in gain is obtained with the loaded configuration. In addition, despite the high reduction in resonance frequency and conductor loading, it is observed that there is no significant change in efficiency of the loaded antenna relative to the original structure. Also, it is seen that the coupling performance, cross-polarization and front-to-back ratio in the radiated fields of the size-reduced antenna remain essentially unchanged relative to the unloaded configuration.

Two-dimensional groove directed microstrip paster antenna

Abstract: Disclosed is a two-dimensional trench-oriented micro-strip patch antenna, which is characterized in that: firstly, the operating frequency f of the patch antenna is established; secondly, the metal plate material is selected and the thickness of the metal plate is h; thirdly, a micro-strip patch antenna is arranged in the central region of the metal plate and is fed with electricity by making use of the coaxial line; fourthly, N1 ring-shaped trenches are cyclically arrayed and distributed on the exit surface of the metal plate with a cycle of P1, a depth of d1 and a width of w1; finally, N2 traditional ring-shaped trenches are cyclically arrayed and distributed outside the trenches with a cycle of P2, a depth of d2 and a width of w2, and the manufacturing is finished; and the invention adopts a theory that the trench structure modulates the surface wave in order to improve the antenna radiation performance and a theory that the traditional trench structure inhibits the metal plate edge surface wave in order to reduce backward radiation, both of which are integrated and used in the micro-strip patch antenna, so as to improve the front to back ratio of antenna radiation energy and obtain significantly enhanced radiation gains, and meanwhile the antenna beam width can be substantially compressed.

Shielding ring structure capable of increasing front-to-back ratio of antenna

Abstract: The utility model discloses a shading ring structure capable of increasing the front-to-back ratio of an antenna, wherein the shading ring is connected with the metal reflecting surface of the antenna. The shading ring structure is characterized in that the shading ring structure consists of a metal circular ring with good conductivity, the cross section of the metal circular ring is L-shaped, the heights of the two sides of the L-shaped shielding are integer multiples of quarterly wavelength of the work center of the antenna. The end surface and the outer side of an antenna housing are wrapped by the shading ring, thereby improving the front-to-back ratio performance of the antenna and having no influences on other indexes. The structure has the advantages of simple manufacture and processing, stable and reliable performance, low cost and good popularization value.

Stacked aperture‐coupled coplanar patch antenna

Abstract: A new concept of aperture-coupled microstrip coplanar stacked patch antenna is investigated to obtain large bandwidth, reasonable front to back ratio using new techniques to overcome regular aperture-coupled disadvantages. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1228–1230, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24290