Wideband Planar Four-Element Linear Antenna Array

This communication presents for the first time a 16-element planar X-band bidirectional antenna array for beamforming applications. The planar (2D) antenna array is comprised of planar polygon slot antenna elements that utilize a metamaterial inspired reactive coupling element. Simulation and measurement results are presented for both a single antenna element and a 16-element planar array, which resides on a Liquid Crystal Polymer (LCP) substrate. Successful comparison between measured and simulated results verifies that the single antenna element achieves a 10 dB return loss bandwidth of 17.5% and the planar antenna array achieves a 10 dB return loss bandwidth of 25% both at a center frequency of approximately 11 GHz. The measured gain of the planar antenna array is more than 14.5 dBi with an efficiency of 65%. The overall size of the planar antenna array is 3.3λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sub> × 3.6λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sub> × 0.0093λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sub> at 11 GHz.

Far-field pattern synthesis of small antenna arrays is a nontrivial problem. Typically radiation patterns are required to exhibit low sidelobe levels, whilst maintaining the ability to scan the main beam in space. Mutual coupling is a pertinent problem when the number of antenna elements is small, often precluding the use of conventional tapering algorithms. In this paper a technique previously employed to compensate for mutual coupling in linear arrays is extended to include small planar antenna arrays. The method consists of the calculation of the coupling coefficients between the array elements, which are then formed into a matrix and used to compensate for the effects of mutual coupling. It is then shown that this method is not suitable for all planar array configurations and a new technique is developed which allows the calculation of coupling matrices for these element configurations. Measured data from a small planar antenna array is presented, with the outlined methods employed to produce low sidelobe sum and difference beams.

This paper presents a novel bidirectional planar monopole antenna array, with its feeding network, to apply for WiFi/Bluetooth and LTE mobile standards. The planar array is comprised of monopole antenna elements that utilise Archimedean spiral slots, inspired as resonance paths, in order to generate multi-band performance. Contrary to conventional structures, the feeding network is composed of three Wilkinson power dividers, for the purpose of providing synchronised output signals over the required frequency range, miniaturising dissipation losses and decreasing mutual coupling. Simulation and measurement results are presented for a single antenna element, an initial Wilkinson power divider and a four-element planar array, which reside on FR4 substrates. Successfully comparison between simulated and measured results verifies that the single antenna element achieves a 10 dB reflection coefficient from 2.2GHz to 2.9GHz, and the planar antenna array illustrates a 10 dB return loss bandwidth from 2.4GHz to 3.1GHz, which could cover WiFi/Bluetooth (2.45GHz) and LTE (2.6GHz) mobile applications. The proposed planar monopole antenna array also obtains large gain, high efficiency, narrow beam, low side lobe level and highly symmetric bidirectional radiation pattern in both E- and H-plane.

In this paper, a planar comb-shaped antenna array for terahertz sensing based on the excitation of spoof surface plasmon modes is proposed. The structure is constructed by an array of three periodic rectangular grooves perforated through metal stripes on top of a silicon substrate. The effective detection of lactose is given as an example to demonstrate the ability of this structure to enhance detection sensitivity. In transmission mode, the sensing signal of lactose using the antenna array was 7.6 times larger than that of using a silicon substrate. In reflection mode, the sensing signal of lactose increased almost 13 times using our proposed antenna array compared to that of using a silicon substrate, exhibiting high sensitivity in terahertz sensing. Further, lactose thickness could be predicted based on the reflectance at the peak using our proposed structure. Our results indicate that the proposed structure has great potentiality in the field of biological and chemical sensing.

A k-band microstrip array antenna with low sidelobe is proposed in this letter. The antenna array is designed for anticollision radar application. It is a planar series-fed antenna array which consists of eight identical linear series-fed arrays with low sidelobe. The linear series-fed arrays are fed by a microstrip line with impedance matching stubs. The characteristic of low sidelobe can be realized by changing the width of the antenna units and the impedance matching stubs. The shorted holes at both ends of the linear arrays are used to enhance the performance of the antenna array in both impedance matching and radiation pattern. The antenna array is simulated, manufactured, and measured. The measurement results agree with the simulation results. The experiment results demonstrate that the voltage standing wave ratio (VSWR) of the antenna is less than 2 in the working frequency band (24.3–24.7 GHz). The sidelobe levels in both E-plane and H-plane of the antenna are less than −23 dB and good cross polarization is also obtained in the working frequency band.

Smart antenna system has been studied extensively for the fifth generation of wireless communication systems, because it has made a system better performance of higher capacity and coverage as well as of power-saving. The present paper introduces a design of planar microstrip patch antenna array for a smart mobile system operating at 28 GHz. The present smart antenna has an adaptive radiation pattern that adjusts its main beam automatically to the desired direction by following the signal environment. This is based on the processing of an algorithm called the Least Mean Square (LMS) resulting in a change in the magnitude and phase of the feeding current for each element in the antenna array. From the obtained results, the main beam can be steered 180 degrees in the phi (azimuth) plane at a constant theta (elevation) angle. The planar antenna array was designed and simulated using CST Microwave Studio and MATLAB software that is used to find the required exciting current for each element. It is found that the antenna bandwidth is greater than 1 GHz while its gain is about 21 dB.

In this paper, a planar beam-forming antenna array is proposed by using the orthogonal radiation modes of coupled antenna system. Mode-decomposition allows channel capacity to be fully exploited while the mutual coupling between closely spaced antennas is significantly reduced. For low profile design, a four-element patch antenna array module implemented in a double-layer substrate is adopted. For experimental demonstration, the simulated and measured results of a 2.4 GHz antenna array fabricated on low-cost printed circuit board are given.

We propose an InGaAs/InAlAs multiple quantum well (MQW) Mach–Zehnder modulator integrated with an array of gap-embedded planar antennas for 60 GHz band radio-over-fiber system. The modulator enables us to directly convert from wireless millimeter-wave (MMW) signals to light-wave signals without any connection cables. A newly designed MQW for the modulator exhibits a large refractive index change at low electric field owing to its unique quantum confined Stark effect, which can achieve push-pull driving in modulation without any external electrical power supply. In addition, by introducing a PIN structure to waveguides, an electric field induced in the antena gap can be applied to a core layer of the waveguide efficiently under the irradiation of MMW signals. The modulator with a 2-element array planar antenna can be driven under an MMW power density of 98 W m−2. We theoretically discuss designs and characteristics of the MQW, planar antenna, and modulator.

Because of the limited installation space for the mobile communication terminal system, the scale of array antenna is small, which means only few elements can be used. In addition, low profile with wide-beam coverage is preferred either. So planar small-scale array antenna with wide-beam coverage has urgent demand in the mobile communication terminal systems. However, there are two issues for the antenna array design with features of planar, small-scale and wide-beam coverage at the same time: 1) main beam of the array cannot steered to desired direction in the wide-angle area due to the strong coupling; 2) performance of the antenna array mainly depends on the performance of each element which is almost anisotropy in the array environment. Some methods [1-4] have been proposed to widen the scanning angle of antenna array, while they are mainly focus on the linear polarization and the scale of array is not strictly restrict. With the hybrid method named invasive weed optimization and active element pattern [5], the main beam of antenna array can steer to the desired direction, while it does not mean that the array has the best beam coverage in the wide area because the gain will dramatically reduced. In this paper, characteristics of planar small-scale array antenna are introduced firstly. Then, a novel antenna element that suitable for the wide-beam coverage is designed. Lastly, with the proposed element, best wide-beam coverage is designed for the given array configuration.

We provide the design of a co-polarized simultaneous transmit and receive (STAR) array antenna, aiming to address the issue of undesired isolation in the antenna domain of the millimeter-wave (mm-Wave) full-duplex co-polarized communication system. As the cornerstone for the design and development of the antenna, the guided-wave structures of the virtual-electric-wall (VEW)-based ridge substrate-integrated waveguide (RSIW) and ridge parallel plate waveguide (RPPW) are proposed and applied to the full-duplex antenna design. Compared with conventional RSIW, VEW-based RSIW has the merits of lower ohmic loss and releasing the fabrication tolerance in the array antenna. Additionally, on the basis of parallel plate waveguide (PPW), the proposed RPPW exhibits a Chebyshev filtering response. The radiating part of the proposed array employs a slot-pair array excited along orthogonal directions by using the preceding guided-wave structures. Among them, the RSIW array serves as the Tx antenna, and the RPPW array is regarded as the Rx antenna. To achieve co-polarized radiation patterns in the boresight direction, the substrate-integrated waveguide (SIW) feed network is integrated into the reverse side of the antenna, providing differential and common-mode excitations for the RSIW-excited and RPPW-fed arrays. Furthermore, the inter-port isolation is effectively ameliorated by inserting the mushroom-type metamaterial between linear arrays. As a proof-of-concept, a shared-aperture full-duplex array operating in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> -band is developed and fabricated to demonstrate the above concept by using standard printed circuited board technology. The measured overlapped impedance bandwidth covers from 38.18 GHz to 39.13 GHz. The measured Tx-to-Rx isolation is greater than 25.5dB in the Q-band. The measured peak gains in Tx- and Rx-mode are 18.4 dBi and 17.8 dBi. The simulation and measurement results show good consistency, verifying the effectiveness of the proposed array in inter-port isolation, array size, planarization, and lightweight, making it suitable for mm-Wave shared-aperture full-duplex communication systems.

A research about design and realization of dual planar bow-tie dipole array antenna at 2.4 GHz will be presented for Wifi Outdoor BTS applications. The proposed antenna should have wide bandwidth, high gain, and ± 45° dual polarization. From the simulation and measurement results of realized antenna we can concluded that our proposed antenna has met the desired specifications; antenna reflection coefficient value <; -10 dB, mutual coupling <; -20 dB, antenna bandwidth exceeds 1.2 GHz, antenna gain reaches 16.62 dBi. Moreover, beside for Wifi Outdoor BTS applications, this implemented antenna actually can be used for another wireless systems simultaneously for GSM 1800 MHz, 3G 2100 Mz, and LTE/Wimax 2300/2500 MHz.

In recent years, several attempts have been made in designing planar array antennas with high directivity. This paper is aimed at investigating the impact of element spacing on the directivity of planar array of monopole antenna. The directivity of antenna with reduced grating lobes can be obtained by carefully varying the inter-element spacing of array antenna. Based on this conception, this paper presents the investigation carried out on the relationship between inter-element spacing and the directivity of planar array of monopole antenna. It went further to highlight the effect on the total fields radiated by the antenna. The inter-element spacing is one of the most important antenna parameters that determine the directivity of the antenna. For a planar array of monopole, the directivity can be improved by varying the inter-element spacing. Four elements uniform planar array antenna and Hadamard matrix method was used to determine element positioning in the array matrix. The simulated results obtained using Matlab, showed that good directivity was obtained by using element spacing between 0.1λ - 0.5λ. Increasing the spacing beyond 0.6λ - 1.0λ also improved the directivity, but generated many grating lobes. As inter-element spacing increased, the grating lobes increased in size, number and levels. The study, therefore, inferred that the best directivity (radiation pattern) can only be obtained when the element spacing is within 0.1 - 0.5λ.

Planar Beam-forming Antenna Array for 60-GHz Broadband Communication

To control the multiple beams in MIMO communication, paper investigated three topology of antenna array. Linear antenna array and planar antenna array formed beams in different direction. Concentric circles planar antenna array were proposed to reduce first side lobe level. Distance between antenna elements influence on the radiation pattern was also discussed. All arrays were fed by Butler network to control amplitude and phase of antenna elements. It was verified that project of MIMO multiple beams was feasible and effective by ADS simulation.

This paper introduces a wideband star-shaped planar antenna with a liquid crystal (LC) material at Ka-band. The antenna array consists of the LC cavity and planar antenna elements with a microstrip feedline. Planar antenna array is designed with eight star-shaped patches. To check the LC dielectric constant at Ka-band, the designed antenna is fabricated and measured result of reflection coefficient(S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> ) ≤ −10 dB shows across the wideband (27 GHz – 40 GHz) without DC biasing with bean scanning from −62° to +5° and gain ≥ 8.15 dBi. The frequency range can be tuned with applied biasing voltage on the LC cavity.