Rotational circularly polarized array antenna for mutual coupling reduction

The development of wideband antennas with low sidelobe level (SLL) is vital for many up-to-date special communication and air traffic control applications. As it has been reported earlier, array antennas have advantages in SLL but are inherently narrower band than reflector antennas. Another question, not easy for array antennas (if being compared with reflectors), is usually the cost. Researchers do their best to extend the bandwidth (BW) of low SLL arrays and reduce their cost. The task to achieve a good SLL is especially difficult in the case of small array aperture because amplitude and phase (A&/spl phi/) errors, the mutual coupling, and edge effects are more influential in this case than for large arrays. In this paper cost effective design approaches are considered for an S-band dipole antenna array with relatively small aperture and potential opportunities are investigated to improve SLL and BW. The cost reduction is provided by use of the printed circuit technology for all antenna components (radiators, beamforming networks, phase shifters) and by minimizing the number of components. The improving of SLL and BW is provided by A&/spl phi/ errors minimization, mutual coupling and edge effect suppression.

Study on isolation and radiation behaviours of a 34×34 array-antennas based on SIW and metasurface properties for applications in terahertz band over 125–300 GHz

The capability of a magnetodielectric superstrate to suppress the surface wave propagation is investigated. It is shown that the capacitively loaded loop (CLL) metamaterial (MTM) superstrate exhibits a high degree of surface wave attenuation. One of the important applications of such structure is to reduce the mutual coupling between the microstrip patch elements in array antennas. The results of numerical simulations show a significant reduction in the mutual coupling between the antenna elements. To verify and confirm the simulation results, a prototype of the CLL-MTM superstrate incorporating an array of rectangular patch antennas are fabricated and tested. The proposed two-element array antenna has a dimension of approximately $1.6\lambda \times 0.9\lambda \times 0.16\lambda $ while achieving a gain and an efficiency of 8.2 dB and 97%, respectively. Measurement shows the mutual coupling reduction of over 55 dB. The CLL-MTM superstrate provides the gain and efficiency almost the same of unloaded array antennas with 0.1 dB and 2% changes, respectively.

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.

Array microstrip antennas typically comprise a number of microstrip patches configured in planar and/or linear arrangements to satisfy some specified radiation characteristics. These arrangements offer several advantages, such as simple in design, light in weight, and ease of integration. However, the arrangements have also some drawbacks, including narrow bandwidth, distorted radiation pattern, and complicated feeding network. Numerous attempts have been proposed to address those drawbacks enhancing their radiation performances, one of which is by utilizing the feeding technique configuration. This paper investigates the comparison of feeding technique configuration for enhancing radiation performance of planar array microstrip antenna. In the investigation, two proposed array antennas which consist of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2 \times 2$</tex> radiating square patches of each are designed on two layers of 1.524 mm thick Rogers 40003C dielectric substrates with the relative permittivity of 3.38. Two different feeding technique configurations are used for each array antenna, namely proximity-coupled feeding and aperture-coupled feeding. Both array antennas which are intended to work at the operating frequency of 3.5 GHz have the same dimensions of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$60 ~\text{mm} \times 60 ~\text{mm}$</tex>. The simulation results show that both feeding techniques could enhance the radiation performance making the proposed array antennas operate at the center frequency of around 3.5 GHz with the maximum gains of more than 4.0 dBi.

Meteor radars have become common and important tools in the study of the climate and dynamics of the mesosphere/lower thermosphere (MLT) region. These systems depend on accurate angle‐of‐arrival measurements to locate the positions of meteor trails in the atmosphere. Mutual coupling between antennas, although small, produces a measurable error in the antenna pair phase differences used to deduce the angle of arrival of incident radiation. Measurements of the scattering parameter matrix for antennas in an interferometric meteor radar array have been made and applied to the existing angle‐of‐arrival calculation algorithm. The results indicate that mutual coupling of antennas in the array produces errors in the zenith angle estimate of less than ± 0.5°. This error is primarily in the form of a gradient across the field of view of the radar, which can be removed using existing phase calibration methods. The remaining error is small but will produce small systematic variations in the height estimates for detected meteors.

This paper discusses the comparative effect of Electromagnetic Band Gap (EBG) structures on two element Microstrip antenna array. The dielectric substrate used is FR-4 glass epoxy with dielectric constant 4.2 and loss tangent 0.0245. The conventional antenna array is resonating at a frequency of 5.53 GHz with a mutual coupling of -17.83 dB. The first proposed antenna array with square slot EBG structure in the ground plane and fractal patch EBG structure on the surface produces a mutual coupling of -50.21 dB and a gain of 8.78 dB at 5.53 GHz. The second proposed antenna array with star slot EBG structure in the ground plane and diamond patch EBG structure on the surface produces a mutual coupling of -51.63 dB and a gain of 7.20 dB at 5.53 GHz. Both the proposed antenna arrays are producing appreciable decrease in back lobe radiation. The antenna arrays are designed using Mentor Graphics IE3D software and measured are obtained using vector network analyzer.

In this paper, a new array antenna configuration based on Electromagnetic Band Gap (EBG) structures has been proposed for 3.5GHz wireless communication systems. The proposed slotted EBG structure, high impedance surface (SHI), consists of three squares and a square ring deposited on a substrate (Rogers RO4350) which has a relative permittivity of 10.2 and a thickness of 1.27mm. Initially a matrix of 3×7 unit cells of EBG structures is introduced between two patches of an array and then a matrix of 3×14 unit cell of EBG structures is integrated between eight patches, which resonate around 3.5GHz (Wi MAX). The insertion of these structures between the radiating elements of an array antenna reduces the mutual coupling and antenna dimensions by approximately (8dB, 11%) and (12 dB, 5%) respectively for two, eight elements array antenna. In addition, the directivity has been slightly improved in the presence of EBG structures, from 4.52dB to 6.09dB for a two-element array antenna, and from 8.18dB to 8.4dB for an eight-element antenna.

This paper deals with the synthesis of monopulse antenna patterns, sum and difference ones, for planar phased array antennas with an elliptical aperture boundary featuring unequal ultra-low peak sidelobe levels (PSLLs) for the two principal planes of its far field. The used synthesis method is the iterative Fourier transform (IFT) approach. The elliptical planar phased array antenna involved in this synthesis contains 3656 open-ended waveguide radiating elements arranged in a triangular element grid and has an aperture width and height of 50λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and 25λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , respectively, where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the wavelength at X-band center frequency 1.0f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . The simulated monopulse pattern results will be compared with those of a 4680-element rectangular planar phased array antenna having the same width, height, radiator type and triangular grid as the elliptical array antenna. The monopulse patterns of the rectangular array antenna meet the same unequal ultra-low PSLL requirements as those of the elliptical array antenna. It will be shown that the elliptical array antenna with a slightly enlarged aperture containing 4170 elements features on receive comparable or even better far-field performance characteristics as that of the rectangular array antenna. All reported far-field pattern simulations take mutual coupling between the array elements into account.

A high isolation, high gain and compact patch antenna arrays that operates in 11.4–11.78 GHz by using fractal defected ground structure (Fractal-DGS) is designed. Performance of the antenna arrays, such as isolation and radiation, are simulated and compared with conventional patch antenna array without Fractal-DGS. As is presented in this paper, the mutual coupling is −33dB at working frequency, it reduces 13dB compared with the traditional antenna array. And the radiation direction is better than conventional antennas too. Higher isolation and stable directional radiation pattern make this antenna array a better choice for millimeter wave communication system.

In the present paper an array antenna is implemented similar to polyphase filters. This type of antenna implementation is shown to reduce the antenna element mutual coupling effect on the array. In an antenna arrangement where the beam properties are controlled from the baseband, the polyphase antenna requires a reduced number of amplifiers than a conventional array antenna configuration.

SummaryThis paper presents the design and performance evaluation of a single‐layer, high‐gain, millimeter‐wave (mm‐wave), corporate–series‐fed, 16‐element circular patch array antenna tailored for the 28 GHz frequency band, pertinent to fifth‐generation (5G) wireless communication systems. The proposed antenna configuration employs a dual‐port feeding technique, where consecutive junction patches are interconnected with two separate feed networks. By simultaneously exciting the two ports with identical amplitude but opposite phases, the antenna achieves high gain directed towards the broadside. The proposed structure is fabricated on a grounded substrate, enabling accurate performance measurement of the prototype. Close agreement between simulated and measured results validates the precision of the designed structure. The measured performance of the proposed antenna configuration demonstrates an impedance bandwidth of 3.79% within the desired frequency band of 27.6‐28.7 GHz for S11 ≤ −10 dB. Experimental measurements demonstrated that the mutual coupling between the two distinct ports is &lt;−30 dB, with a diversity gain exceeding 9.99 dB. Simulated radiation efficiency exceeds 90% at the 28 GHz center frequency, while the measured peak gain approaches 17.7 dBi. Measured stable radiation plots specify that the proposed array exhibits broadside patterns with half‐power beamwidths (HPBWs) of 30.4° and 11.3°, sidelobe levels (SLLs) below −25 and −10 dB, and cross‐polarization levels &lt;−25 dB in both the E and H planes, respectively. The superior performance characteristics of the proposed array antenna make it well‐suited for 28 GHz mm‐wave 5G applications, facilitating efficient and reliable long‐range communication in the mm‐wave spectrum.

This study presents a hybrid electromagnetic isolation mechanism in a transceiver array antenna operating at 5.8 GHz. Maximum isolation between transmitting and receiving array antennas, at a very close spacing (3 mm = 0.058 λ 0 ), and minimum mutual coupling between each array elements is achieved without antenna radiation pattern degradation. The achieved separation is equivalent to 44% size reduction compared with conventional half wavelength spacing criterion. Each of the transmitting and receiving array antennas is a four-element linear microstrip patch array antenna. The employed hybrid isolation technique is composed of defected ground structure, to minimise coupling between array elements, and uniplanar electromagnetic bandgap, to minimise the coupling between the transmitting and receiving antennas. The resulting transceiver array antenna system fulfils -35 dB mutual coupling between array elements, and 60 dB isolation between opponent transmitting and receiving array antennas. The proposed design procedures are discussed and analysed using electromagnetic full wave simulations. Results were verified through experimental measurements for reflection coefficient, mutual coupling and radiation characteristics in which a good agreement with simulated results is granted.

A Sub-6 GHz band radome-covered omnidirectional horizontally polarized large spacing array antenna is reported with low grating lobe and low mutual coupling. A designed dielectric radome is utilized to replace several layers of antenna elements under the same effective aperture. The radome extends the current distribution and thus increases the effective aperture of the array element so that the array element spacing can be enlarged. Fewer antenna element is required with the radome introduced, compared with conventional spacing antenna array. Meanwhile, the large spacing decreases the mutual coupling between neighboring layers while no apparent grating lobe appears. The effectiveness of the proposed structure is evaluated by both simulation and experiment. And the mutual coupling and the grating lobe of proposed radome-covered antenna are also discussed. In the experiment, the 4-element 1-layer array model is considered. Proposed antenna is ideal for B5G application requiring fewer horizontal polarized sources covering the entire azimuth plane.

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.