Single-fed Microstrip Research Articles

Polarization Enhancement of Microstrip Antennas by Asymmetric and Symmetric Grid Defected Ground Structures

A new approach to controlling cross-polarization (XP), for either suppressing XP or exciting circular polarization (CP), in single-fed microstrip antennas using novel grid defected ground structures (GDGSs) is proposed. The key idea of GDGS is to construct defected ground structures (DGSs) from a grid of etched slots on a ground plane. The properties of each slot can be directly set by using either an open or short with fixed hardwires. The overall fixed hardwire configuration of the GDGS can be found straightforwardly by optimization of the XP or CP characteristics of the microstrip antenna. The importance of the approach is demonstrated by the results achieved. Results from two experimental prototypes are provided that demonstrate XP can be suppressed by 15 dB and CP can be excited with 78 MHz (2.2%) 3-dB axial ratio (AR) bandwidth and 6.6 dBic gain respectively on single-fed microstrip patch antennas.

Broadband Circularly Polarized Microstrip Patch Antenna Using Circular Artificial Ground Structure and Meandering Probe

To enhance axial ratio (AR) bandwidth, this research proposes a circularly polarized (CP) single-fed microstrip patch antenna using a circular artificial ground structure (AGS) and meandering probe. To achieve broader AR bandwidth, the circular AGS is populated with rectangular unit cells and partially cut unit cells along the circular contour, while the meandering probe is used to improve the impedance bandwidth. Simulations are performed and results compared with that of conventional rectangular-AGS antenna. The simulation results show that the circular-AGS antenna, given 62 mm circular ground plane, achieves broader impedance (5.12 - 9.00 GHz and 54%), AR (5.21 - 8.27 GHz and 45%) and gain bandwidths (3.85 - 7.00 GHz and 58.06%), in comparison with the rectangular-AGS antenna (4.50 - 7.45 GHz and 49%; 4.52 - 7.42 GHz and 21%; and 4.00 - 6.80 GHz and 51.58% for impedance, AR and gain bandwidths). The circular-AGS antenna is capable of converting linear polarization in the off-axial ratio band into circular polarization. To verify, a circular-AGS antenna prototype is fabricated and experiments undertaken. The experimental impedance, AR and gain bandwidths of the circular-AGS antenna are 47.82% (5.17 - 8.42 GHz), 43.81% (5.24 - 8.17 GHz) and 60.74% (3.75 - 7.00 GHz). The proposed circular-AGS antenna can achieve broader AR bandwidth and is thus ideal for broadband CP applications. The novelty of this research lies in the use of circular AGS to effectively enhance AR bandwidth, as opposed to rectangular AGS which is conventionally used in CP polarizers.

Single-Fed Wide-Beamwidth Circularly Polarized Patch Antenna Using Dual-Function 3-D Printed Substrate

This letter presents a novel single-fed microstrip patch antenna using three-dimensional (3-D) printed substrate for both circular polarization and wide 3 dB axial-ratio beamwidth (ARBW). Here, the substrate consisting of a photosensitive resin and air with a square mesh-grid structure is dual-function. On the one hand, the permittivity of the substrate in two orthogonal directions is tuned to be slightly different by inserting two resin chunks. Hence, the asymmetry of the substrate can split the two degenerate modes of the patch antenna so as to generate circularly polarized waves. On the other hand, the effective permittivity of the substrate can be freely controlled by the volume fraction of air, and thus influences the 3 dB ARBW. As a result, wide ARBW can be realized by properly configuring substrate through a 3-D printing process. A prototype is fabricated and measured. Measured results are found in reasonably good agreement with the simulated ones, exhibiting a 3 dB ARBW as wide as 120°.

High-Gain Circularly Polarized Microstrip Patch Antenna With Loading of Shorting Pins

A single-fed microstrip patch antenna (MPA) with loading of shorting pins for high-gain circularly polarized (CP) radiation is proposed in this paper. Two sets of metallic pins are symmetrically placed along the two orthogonal diagonals of a square patch radiator at first. Due to the shunt inductive effect brought by these shorting pins, the resonant frequency of the dominant mode in this MPA is progressively tuned up so as to enlarge the electrical size of this pin-loaded patch resonator and to enhance its radiation directivity. After the optimal loading position is investigated for maximum directivity of linear polarization, one pair of the inner pins is slightly shifted in an offset to properly separate the two degenerate modes, so that the CP radiation can be excited. Moreover, upon request, either left-handed or right-handed circular polarization can be obtained by means of different position-offset scheme of the inner pins along the diagonals. After extensive analysis is executed, two equal-size CP MPAs with and without shorting pins are fabricated and tested. Simulated and measured results show good agreement and demonstrate that the CP directivity is enhanced from 8.0 (conventional MPA) to 10.8 dBic, indicating a 2.8-dB increment by means of the proposed approach.

A novel reconfigurable microstrip patch antenna with frequency and polarization diversities

A single-fed microstrip patch antenna with frequency and polarization diversities is presented in this article. The proposed antenna consists of a square patch fed along its diagonal line with four parasitic stubs added around its four sides connected by four PIN diodes. The center of edges of two stubs far away from the feed point is connected to ground via another two diodes, while those of the other two stubs are connected to ground via capacitors. By turning these diodes on and off, the antenna has five different operating states. It is capable of switching between right hand circular polarization and left hand circular polarization in the frequency band (2.422–2.448 GHz), and also can operate at two frequency bands with horizontal and vertical polarization or vertical and horizontal polarization, respectively. In addition, it can radiate 45° linear polarization as a traditional patch antenna fed along its diagonal line. The measured results verify the reconfigurable characteristics of the antenna and demonstrate that it is a good candidate for wireless communication applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1494–1500, 2015

저가 3차원 빔 조향을 위한 단일급전 마이크로스트립 기생배열 안테나

저가 3차원 빔 조향을 위한 단일급전 마이크로스트립 기생배열 안테나

Wideband single-fed circularly polarised patch antenna

A novel circularly polarised (CP), single-fed microstrip antenna is presented. The antenna consists of a stacked structure of almost square patches. The proposed design has a reduced antenna size compared to the conventional CP microstrip antenna at a given operating frequency. The impedance and axial ratio bandwidths are large and CP radiation quality is excellent over the entire upper hemisphere. The proposed antenna is suitable for global positioning system (GPS) applications.

Circularly polarized single-fed wide-band microstrip patch

For more than 25 years, the circularly polarized single-fed microstrip patch was considered to be extremely narrow-band. The reported performances are almost exclusively related to single patches printed on a dielectric substrate, which partially explains the frequency characteristics. The antenna proposed is a variation of the "almost square" patch and exhibits measured axial radio of less than 2.5 dB over a 13% bandwidth. The antenna was designed for wireless applications.