Feeding Technique Configuration for Enhancing Radiation Performance of Planar Array Microstrip Antenna

In this paper, a dual-polarized microstrip array antenna with orthogonal feed circuit is proposed. The proposed microstrip array antenna consists of a single substrate layer. The proposed array antenna has microstrip antenna elements, microstrip lines, air-bridges and cross slot lines. For dual polarization, an orthogonal feed circuit uses the Both-Sided MIC Technology including air-bridges. The Both-Sided MIC Technology is one of the useful MIC technologies for realizing a simple feed circuit. The air-bridges are often used for MMICs because it is possible to reduce the circuit complexity. The characteristics of proposed array antenna are investigated by both the simulation and the experiment. Consequently, it is confirmed that the proposed array antenna with the orthogonal feed circuit has dual polarization performance with very simple structure. The proposed array antenna will be a basic technology to realize high performance and attractive multifunction antennas.

This paper presents rotational circularly polarized array antenna at 12 GHz. Array antenna degraded radiation performance because of mutual coupling between adjacent elements. General array antenna has same direction port each single elements. However, proposed rotational array antenna has different direction port to reduce the mutual coupling. As a results, mutual coupling of 2 by 2 rotational array reduce the about 10 dB compare with conventional array antenna. So proposed array antenna is better radiation performance than conventional; improve the realized gain, axial ratio, sidelobe level and efficiency.

One of important parameters in array antenna is radiation characteristic which can be satisfied by implementing several design techniques. In this paper, by utilizing differentially proximity-coupled feeding technique, a circular ring-shaped array antenna is designed with improved radiation pattern characteristics. The proposed array antenna consists of 20 circular ring-shaped antenna elements arranged in 4 $\times$ 5 array. Differentially proximity-coupled feeding technique applied for each antenna element is aimed to have symmetrical radiation pattern. The array antenna which is designed to work at the frequency of 1.275 GHz for L-band frequency application is implemented using two layers of FR4 epoxy dielectric substrate with the total dimension of 199.3 mm $\times$ 189.5 mm. The characterization result shows that the proposed array antenna has good impedance matching with the reflection coefficient $(S_{11})$ of −21.65 dB and −10 dB impedance bandwidth of 80 MHz (1.21 GHz to 1.29 GHz). Meanwhile, a symmetrical radiation pattern at $E-$ plane is achieved with the half power beamwidth (HPBW) of 43°.

In this paper, the proposed antenna consists of a single transmission line for 6-elements microstrip array antenna using Rogers RT5880 substrate material with a dielectric constant (εr) of 2.2 and thickness of 0.787 mm for navigation applications. The array structures of unequal patches placement are proposed with corporate feed line and H-shaped configurations are employed on the substrate and used the microstrip feed line with a corporate feed network excited via 50 Ω with T-junction method to control the feed for each group. 6-elements microstrip array antenna has operated at the resonant frequency of 1.27 GHz was obtained between the frequency from 1.2663 GHz to 1.2734 GHz where the S11-parameters of the structure designed and simulation below than <-10 dB. The analysis shows the antenna gain has increased 72.6% with high directivity as compared to single elements microstrip antenna. The radiation characteristics and other array parameters are evaluated with respect to the application requirements. However, circular polarization has obtained in 6-elements array antenna as the axial ratio is successfully achieved below than -3dB. The antenna efficiency, the current distribution, VSWR, and S11-parameters of the proposed 6-elements CP microstrip array antenna have been presented and discussed in detail. The design methodology and the measurement results have been presented and discussed in this paper.

High gain array antenna for 24 GHz FMCW automotive radars

In this paper, a linear polarization switchable planar array antenna with enhanced gain and better crosspolarization is proposed. The proposed array antenna consists of a fed patch and four parasitic patches. Four switching diodes are loaded on the corners of the fed patch. The boundary condition of the fed patch is controlled by using the ON/OFF condition of the diodes, and the polarization angle of the array antenna can be orthogonally switched to §45 - with better than i22dB of crosspolarization. The simulated gain of the array antenna is remarkably increased to 12dBi by using four parasitic patches surrounding the fed patch. For matching the resonance frequency of the parasitic patches with the fed patch, a square slot is formed at the center of each parasitic patch. The characteristics of the proposed array antenna are investigated by the FDTD simulation method. The array antenna is fabricated and the experiment is carried out. Both the simulation and the experimental results of the proposed array antenna demonstrate the polarization switching functionality successfully with the enhanced gain in S-band.

This research has proposed a planar rectangular dipole antenna enclosed in double C-shaped parasitically slit elements (i.e., radiator element) on a double-cornered reflector for bandwidth enhancement. In the study, simulations were first carried out to determine the optimal parameters of the radiator element and then a radiator element prototype was fabricated and mounted onto a double-cornered aluminum reflector. The simulated and measured |S11|<–10 dB of the antenna element covered the frequency ranges of 451–901 MHz (66.6%) and 455–886 MHz (64.3%), respectively. The gain was enhanced by the subsequent deployment of multiple radiator elements to fabricate a four-element vertically array antenna on an elongated double-cornered reflector. The simulated and measured |S11|<−10 dB of the array antenna, respectively, covered the 410–991 MHz (82.9%) and 415–886 MHz (72.4%) frequency ranges. The proposed array antenna radiates unidirectionally across the DTV frequency band with a measured front-to-back ratio and cross polarization >20 and <−23 dB, respectively. The simulated and measured half-power beam widths in the E and H planes were respectively 56° ± 13° and 20° ± 6°; and 57° ± 13° and 21° ± 6°. In addition, the simulated and measured gains of the array antenna were 12.8–16.4 dBi and 11.3–15.8 dBi along the 470–862 MHz frequency range. This proposed array antenna is thus suitable for DTV broadcasting transmission. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:466–478, 2016.

In this paper, a planar circular patch array antenna that features electric fields focused in the near-field zone for 2.4 GHz radio frequency identification (RFID) applications is presented. This array antenna is implemented by using six circular patch elements and a microstrip feeding network with a proper input phase for each element. The array antenna is capable of enhancing electric field distributions in the near zone to charge and interrogate dipole-like passive tags near the array antenna by capacitive coupling. Readable range is measured for up to 12 tags lined up closely with 1 cm spacing. Applications using the proposed array antenna with an RFID reader by Sunlit are discussed.

An in-band low radar cross section (RCS) microstrip patch antenna based on a phase control metasurface is proposed. As the size of the phase control metasurface changes, it will have different phase adjustments to the incident electromagnetic wave. Two kinds of phase control metasurfaces with a 90° reflection phase difference are arranged in a checkerboard configuration and loaded above a microstrip array antenna. The metal of the microstrip array antenna can fully reflect the electromagnetic wave, so the incident wave passes through the metasurface again and forms a reflected wave with a phase difference of 180° ± 37° when passing through the phase control metasurfaces of different sizes. Thus, the microstrip array antenna can achieve in-band RCS reduction. The metamaterial forms a transmission window in the microstrip patch array antenna band to maintain the radiation performance. Finally, a reasonable agreement is obtained between the measured and simulated results.

In the present paper radiation performance of a right triangular microstrip antenna are investigated in two component warm ionized plasma medium comprising of electrons and ions together and expressions of the field intensities for electromagnetic and electroacoustic modes for this antenna mounted on a re-entry vehicle are derived by applying linearized hydrodynamic theory coupled with vector function technique. With the variation in plasma parameter, the performance of antenna is analyzed to reach a limiting condition where no communication between radiator and receiver is possible.

This aticle presents a new wideband omnidirectional array antenna that operates at Ku‐band. Each element of the array antenna consists of a modified planar bow‐tie dipoles radiator, a pair of parasitic strips, and a pair of directors. The parasitic strips and directors are designed to enhance the antenna omnidirectional radiating performance. All elements are combined through a double‐sided parallel strip‐line feeding network. A wideband semicircular balun is employed at the feeding port to broaden the impedance bandwidth. Finally, a 2 × 2 prototype is designed, fabricated, and measured. The measured results demonstrate that the proposed array antenna provides 47.3% (11.3‐18.4 GHz) relative impedance bandwidth with 4.1 dBi maximum gain, around 44.8° half‐power beamwidth at 15.0 GHz and less than 2.5 dB unroundness over the whole operating band in xoy plane.

This paper deals with the design of 2.4 GHz slotted substrate integrated waveguide (SIW) array antenna for wireless local area network (WLAN) application. The use of SIW structure is addressed to achieve a compact shape of waveguide-based array antenna especially at low frequency region. The proposed array antenna which is intended to work at the frequency of 2.4 GHz applies several configurations of longitudinal slot array on an SIW surface. A 1.6 mm thick FR4 epoxy dielectric substrate is used to deploy the design of SIW-based slotted waveguide array antenna. The performances of array configuration as well as the effect of slots number are investigated to attain the specified requirement. A 4.8 dBi gain could be achieved by a 1 × 2 slotted waveguide array antenna which has 8 slots in each array configuration.

A low-profile phased array antenna with wideband wide-scan characteristics has been presented. An aperture coupled feed mechanism and dual-layer radiating patches are adopted to achieve wideband impedance matching. Due to the piled dielectric slabs, the performance of microstrip antenna arrays is normally deteriorated by surface waves when scanning to large angles. To solve this issue, the stacked slabs have been perforated to the greatest extent to suppress surface wave propagation. Additionally, two pairs of parasitic strips have been designed to improve the antenna performance in the lower band without increasing the antenna profile. The thickness of the array is only <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.19\lambda_{h}(\lambda_{h}$</tex> refers to the wavelength at the highest operating frequency in free space), indicating the good potential for low-profile applications. The proposed array antenna has achieved relative bandwidths of 57.9% (active VSWR <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\leqslant 2.25$</tex> ) and 44.4% (active VSWR <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\leqslant 2.75$</tex> ) for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 45^{\circ}$</tex> scanning and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 60^{\circ}$</tex> scanning, respectively.

In the conventional routes to obtain stealth array antennas, various techniques are used to reduce the radar cross sections (RCSs) of existing antennas based on experience-relying trial-and-error and time-consuming optimizations. To address the issue, we propose reverse thinking, i.e., low scattering performance precedes radiation performance, and present a universal and definite route to achieve low-RCS array antennas directly from metasurfaces rather than from antennas. A specific design method is carefully elaborated to illustrate this route. First, a low RCS metasurface is designed. Then an interdigital arrangement of the metasurface and proper feeding techniques are exploited to excite parts of the metasurface cells to produce efficient radiations. These partially excited cells play twofold roles as the radiating structures for array antenna and as part of scattering structures for the low-RCS property. As examples, 1-D and 2-D metasurface-based array antennas are elaborately designed and fabricated, in which good radiation performance and broadband low RCSs are achieved simultaneously. Both numerical simulations and experimental results verify the effectiveness of the proposed method. It suggests that the proposed route is more likely to speed up the design process and yield an integration structure and controllable performance.

This paper presents a comparative study of radiation performance between two Ultra Wide Band (UWB) microstrip planar array antennas for weather RADAR applications which operate in C band. These arrays are etched onto a FR4 printed circuit board with an overall size of \((162 \times 100 \times 1.58)\) mm3 and dielectric constant \(\upvarepsilon_{\text{r}} = 4.4\). The proposed arrays antennas are composed of a twenty radiating patch element with a T-junction power divider which has a role to divide the power equally to all antenna elements above a partial ground plane. Simulation results show that each array antennas has its own characteristics. The results show that the use of an array antennas with rectangular radiating elements give a bandwidth which is about 118 %, gain and high directivity can exceed 12 dB and a half power beam width of 10°, which are relatively closer to those obtained in array antennas with circular radiating elements.