Two-element Antenna Array Research Articles

Mutual Coupling Reduction in Antenna Using EBG on Double Substrate

In this paper, a mutual coupling study is conducted between two-element array antenna on dual substrate. A single patch antenna is firstly designed on dual substrate layer to testify appropriate performance at 2.45 GHz. Subsequently, an array of two element patches on dual substrate are constructed with one of them is incorporated with three EBG unit cell on the bottom substrate. The radiating patch is on the top substrate, while the EBG unit cell is on the bottom substrate. With EBGs in separate layers from the antenna array, the antenna elements are closely separated by a distance of 22 mm with a significant reduced mutual coupling of -26.61 dB. This corresponds to a distance reduction of 34.68%. The proposed structure implemented only three EBG unit cells. Apart from that, the study of overlapped case of EBG with the antenna is also presented.

Asymmetric dual-band integrated compact CRLH SIW array antenna

In this paper, we introduce a compact dual-band two-element array antenna in a substrate integrated waveguide (SIW) configuration for C-band applications. A new geometry based on an asymmetric composite right–left-handed transmission line cells was suggested for the single antenna element. The proposed geometry has the advantage of having arbitrary dual-frequency design. The array elements are fed with a wideband SIW impedance transformer. The results indicate that the proposed antenna element size is only 15 × 12.8 mm2, which approximately represents up to 70% size reduction at similar frequencies. The radiation properties of the array antenna have broadside radiation pattern at the two bands. The detailed analytical design explanation, full wave simulations, and experimental measurements are introduced.

Design, Fabrication, and Measurement of Dual-Segment Rectangular Dielectric Resonator Antenna Array Excited with Conformal Strip for S-Band Application

ABSTRACTA conformal strip connected to a microstrip line is proposed to excite the professed dielectric resonator antenna array to achieve the critical coupling for material having lower dielectric constants of less than 10. Fabrication of two-element dual-segment linear broadside rectangular dielectric resonator antenna array with copper plates on one side has been successfully presented for the first time. The combination of high gain and wide bandwidth with low cross-polarization is always a challenge for researchers. The gain of a two-element array has been increased by a factor of 2.0 compared with the gain of a single dielectric resonator antenna, and there is also a 6.14% increase in bandwidth of the proposed array compared to the single element rather than a decrement in bandwidth as reported in previous studies. Although the gain and bandwidth are not very high for the two-element case, the proposed fabrication technique can be applied for a large number of elements for higher gain application, and the structure can be modified for other desired bands of operation. The proposed array can be used as a medium-gain wideband antenna or can form a sub-array in a large low-profile structure for high-gain applications.

Investigation of the effects of metal-wire resonators in sub-wavelength array based on time-reversal technique

The resonant metalens consisting of metal-wire resonators with equally finite length can break the diffraction barrier well suited for super-resolution imaging. In this study, a basic combination constructed by two metal-wire resonators with different lengths is proposed, and its resonant characteristics is analyzed using the method of moments (MoM). Based on the time reversal (TR) technique, this kind of combination can be applied to a sub-wavelength two-element antenna array with a 1/40-wavelength interval to make the elements work simultaneously with little interference in the frequency band of 1.0-1.5 GHz and 1.5-2.0 GHz, respectively. The simulations and experiments show that analysis of MoM and the application of the resonators can be used to design multi-frequency sub-wavelength antenna arrays efficiently. This general design method is convenient and can be used for many applications, such as weakening jamming effectiveness in communication systems, and sub-wavelength imaging in a broad frequency band.

Nonlinear Effects of Power Amplifiers on Adaptive Antenna Systems

A systematic method is first proposed for numerically analyzing the nonlinear effects of a power amplifier on adaptive arrays. By using the proposed method, the bit error rate (BER) degradation caused by the nonlinear distortion of amplifiers on a nine-element adaptive antenna system (AAS) was numerically analyzed using a least mean square (LMS) adaptive algorithm. A closed form was first derived to analyze the radiation pattern degradation of the null shifting caused by the amplifier’s nonlinear distortion. The obtained data were then compared with the measured results of a two-element antenna array with two amplifiers. The concordance of the theoretical and measured data verified the proposed method.

Array Mutual Coupling Reduction Using L-Loading E-Shaped Electromagnetic Band Gap Structures

A mutual coupling reduction method between microstrip antenna array elements is proposed by using periodic L-loading E-shaped electromagnetic band gap structures. Two identical microstrip patch antennas at 2.55 GHz are settled together and used to analyze the performance of the designed two-element antenna array. The two antenna elements are settled with a distance of about0.26λ. To reduce the mutual coupling, the L-loading E-shaped electromagnetic band gap structures are used between these antenna elements. The simulated and measured results show that the isolation of the antenna array reaches 38 dB, which has a mutual coupling reduction of 26 dB in comparison with the antenna array without the decoupling structures.

An LTCC Coupled Resonator Decoupling Network for Two Antennas

An integrated low-temperature co-fired ceramic (LTCC) coupled resonator decoupling network (CRDN) for two coupled antennas is proposed in this paper. By virtue of LTCC technology, a second-order CRDN is realized by two tightly coupled lumped-element resonators in a volume of 3.2×2.5×1.2 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . Theoretical analysis has revealed that a wide range of mutual admittance of a CRDN can be realized by choosing appropriate I/O coupling elements while the coupled resonators can be consolidated in an LTCC device. This “one-fit-all” feature allows for decoupling a wide range of coupled antennas with different form factors for a given frequency band. To prove the concept, two LTCC CRDNs for decoupling different forms of antennas working in the 2.45-GHz band are designed, fabricated, and tested. Measurement results have demonstrated that significant improvement in isolation can be achieved within a wide operating frequency range in all cases. The presented design theory and circuit topology are general and can be applied to both symmetric and asymmetric two-element antenna arrays.

A Partially Magnetized Ferrite LTCC-Based SIW Phase Shifter for Phased Array Applications

The theory and design of a half-mode substrate-integrated waveguide ferrite low-temperature cofired ceramic-based phase shifter are presented in this paper. Unlike typical ferrite-based designs, the biasing is done through embedded windings in a multi-layer substrate that not only obviates the requirement of bulky electromagnets, but also prevents loss of bias fields at the air-to-ferrite interface. The phase shifter is operated in the partially magnetized state of ferrite substrate. Through the combined effect of embedded windings, half-mode waveguide operation, and partially magnetized state, the required bias fields have been reduced by 90% as compared with conventional ferrite-based designs employing electromagnets. A complete analytical model, backed up by electromagnetic simulations and measured results from a prototype, is presented in this paper. The fabricated prototype demonstrates a phase shift of 83.2° at a center frequency of 13.1 GHz and a figure of merit of 83.2°/dB. As a proof-of-concept, the proposed phase shifter design is monolithically integrated with a two-element antenna array to demonstrate a measured beam steering of 30°. The phase shifter design is highly efficient in terms of required bias fields, and it has a small form factor and can be easily integrated with other electronic components and systems.

NOVEL WEARABLE EAGLE SHAPE MICROSTRIP ANTENNA ARRAY WITH MUTUAL COUPLING REDUCTION

Novel eagle shape microstrip wearable antennas (element and array) are presented. The single- and two-element antenna arrays are designed and fabricated on a Roger RT/Duroid 5880 substrate with dielectric constant of 2.2, thickness of 1.5748 mm, and tan δ =0 .001. The measured results show that a reduction in mutual coupling of 36 dB is achieved at the first band (1.68-2.65) GHz and 22.1 dB over the second band (6.5-8.86) GHz due to introducing electromagnetic bandgap (EBG) structures. EBG structure has an eagle-like shape with more gaps. By increasing the number of EBG cells and varying the gap distance between cells to certain limit, the mutual coupling reduction is improved. Also, a size reduction of 80% is achieved. The microstrip array was simulated by CST simulator version 2014 and fabricated by proto laser machine with precision 25µm. The specific absorption rate (SAR) investigation is carried out on CST2014 Simulator. Maximum SAR value is 1.953 W/kg which indicates that the eagle-shaped microstrip wearable antennas are safe for human. The antennas can be used in the official or RFID applications.

Applications of Generalized Cascade Scattering Matrix on the Microwave Circuits and Antenna Arrays

The ideal lossless symmetrical reciprocal network (ILSRN) is constructed and introduced to resolve the complex interconnections of two arbitrary microwave networks. By inserting the ILSRNs, the complex interconnections can be converted into the standard one-by-one case without changing the characteristics of the previous microwave networks. Based on the algorithm of the generalized cascade scattering matrix, a useful derivation on the excitation coefficients of antenna arrays is firstly proposed with consideration of the coupling effects. And then, the proposed techniques are applied on the microwave circuits and antenna arrays. Firstly, an improved magic-T is optimized, fabricated, and measured. Compared with the existing results, the prototype has a wider bandwidth, lower insertion loss, better return loss, isolation, and imbalances. Secondly, two typical linear waveguide slotted arrays are designed. Both the radiation patterns and scattering parameters at the input ports agree well with the desired goals. Finally, the feeding network of a two-element microstrip antenna array is optimized to decrease the mismatch at the input port, and a good impedance matching is successfully achieved.

Dual-Frequency Two-Element Antenna Array with Suppressed Mutual Coupling

An efficient technique utilizing the defected ground structure (DGS) to suppress the mutual coupling effect of a dual-frequency microstrip antenna array is studied. The proposed dual-frequency DGS beneath two patches includes two circular split ring slots, each of which corresponds to one resonant frequency of the patches. The characteristic of the compact DGS is theoretically and experimentally investigated. The prototypes of the patches arrays with and without the proposed DGS are fabricated. Both the simulated and measured results show that the mutual coupling between array elements has been obviously reduced at the two operating frequency bands with the implementation of the proposed DGS structure.

A PROPOSED DESIGN OF UWB MONOPOLE ANTENNA AND ITS LINEAR ARRAYS

A proposed design of ultra-wideband (UWB) monopole antenna has been presented to cover frequency range 2.49–14.42 GHz with small size. An equivalent circuit model with the parameter values of the optimized UWB antenna has been modeled. Moreover, a compatible lumped-elements utilized in equivalent circuit modeling for the proposed monopole antenna is established using the Advanced Design System (ADS). An UWB feeding network circuit has been designed in order to be used for exciting 2x1 and 4x1 linear antenna array. The measured and simulated results for the proposed feed network has a good return loss, isolation and power division ratio at all ports within the whole UWB frequency range. Two and four element UWB linear antenna arrays are presented. The average gain for the two-element antenna array is about 5.3 dBi and reaches to7.15 dBi for the four-element antenna array, over the whole UWB frequency range. A good agreement between the measured and the simulated results of all parameters for the antenna element and antenna arrays is appeared.

A 1 &lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;$\times$&lt;/tex&gt; &lt;/formula&gt; 2 Dual-Band Antenna Array for Radio-Frequency Identification (RFID) Handheld Reader Applications

In this paper, an aperture-coupled dual-band antenna array for ultra-high-frequency (UHF) and microwave band radio-frequency identification (RFID) handheld reader application is presented. The proposed two-element antenna array is composed of a feeding network, a ground plane with coupling apertures, patch radiators, and parasitic elements serving as directors. The spacing between the radiators is optimized to achieve the desired radiation patterns. The experimental results demonstrate that the proposed antenna features good impedance bandwidth, moderate gain, and good radiation efficiency from 840 to 960 MHz (covering a universal UHF band) and 2.38-2.48 GHz (microwave band). The antenna is well suited for applications in RFID handheld readers.

Decoupling Network Comprising Transmission Lines and Bridge Resistance for Two-Element Array Antenna

Decoupling Network Comprising Transmission Lines and Bridge Resistance for Two-Element Array Antenna

Development of 60-GHz Wireless Interconnects for Interchip Data Transmission

This paper presents radio frequency data transmissions via 60-GHz antennas or wireless interconnects in multichip multicore computing architectures. An antenna in package is used as the design configuration to be placed on top of the silicon circuitry. The packaging design includes an artificial magnetic conductor to enhance the operating bandwidth, a two-element antenna array to increase the transmission gain, and an integrated power divider. This paper compares the wireless link budget of antenna-based interconnects in terms of the Friis transmission equation. This defines the power needed to be recovered by wireless transceivers (PRE). The design demonstrates an 11 GHz measured operating bandwidth and shows that with a two-element array; the PRE is reduced by 10 dB over that with a link that uses a single antenna.

Biomimetic Antenna Arrays Based on the Directional Hearing Mechanism of the Parasitoid Fly Ormia Ochracea

We present a thorough examination of two-element antenna arrays that mimic the sense of directional hearing of the parasitoid fly Ormia Ochracea and examine the design tradeoffs of such arrays. Recently, it was demonstrated that these antenna arrays demonstrate enhanced sensitivity to the direction of incidence of an electromagnetic wave, compared to regular arrays occupying the same aperture. This, however, comes at the expense of sacrificing the available power at the outputs of such arrays. In this paper, we present a model for these two-element biomimetic antenna arrays (BMAAs) that takes the mutual coupling effects into account. Using this model, we examine the tradeoffs that exist between the phase enhancement, which can be achieved from these arrays, and their output power levels. We demonstrate that for any given desired phase enhancement factor, an optimum BMAA design exists that maximizes the output power level of the array. We also show that strong mutual coupling between the two antennas can be exploited to enhance the output power of the array. A method for designing practical two-element BMAAs is also presented along with simulation and measurement results of a fabricated prototype.

Effects of Phase Difference in Dipole Phased-Array Antenna Above EBG Substrates on SAR

In this letter, we investigate the specific absorption rate (SAR) of a dipole phased-array antenna above an electromagnetic band-gap (EBG) substrate. A two-element array antenna above an EBG substrate is considered for fourth-generation mobile applications at the 3.5-GHz band. The computational results indicate that the use of an EBG substrate in a phased-array antenna can provide an SAR reduction of over 70%. The SAR reduction also depends on the phase difference of the phased-array antenna.

A HIGH-GAIN BROAD-BAND WAVEGUIDE LONGITUDINAL SLOT ARRAY ANTENNA

This paper presents method of moments based analysis of high-gain broad-band waveguide broad-wall longitudinal slot array antenna. Initially a basic two-element slot array antenna has been analyzed, and corresponding scattering parameter data have been obtained. The theoretical data have been compared with experimental data and Ansoft HFSS's simulated data to validate the proposed method. The excellent agreement obtained between the results validates the analysis. After validating the methodology, attempts have been made to design a broad-band high-gain slot array antenna. An 18-element slot array antenna has been designed, fabricated and tested. The fabricated antenna provides a high gain over large band width.

유한한 기판 크기가 2소자 E-평면 선형 배열 안테나의 방사 특성에 미치는 영향

The effect of a finite substrate size on the radiation characteristics of a two-element linear E-plane array antenna using microstrip patch antennas is investigated. The average active element pattern characteristics of two-element E-plane array antennas printed on different dielectric constant substrates with various substrate sizes and element spacings are analyzed. Using the average active element pattern, the radiation pattern characteristics of the array antenna versus scan angle is analyzed. The simulation results show that the diffracted fields of surface waves from substrate edges have a significant effect on the radiation characteristics of a 2-element E-plane array antenna. The distance between the center of patch antenna and the substrate edges on the E-plane for the enhancement of radiation characteristics of the array antenna is about .

Electrically Small Superdirective Endfire Arrays of Metamaterial-Inspired Low-Profile Monopoles

This letter presents the design and experimental characterization of subwavelength, superdirective, endfire antenna arrays operating in the 2.45-GHz band. Microstrip-fed, low-profile folded monopoles are designed using metamaterial-inspired phase-shifting lines composed of inductively coupled spiral resonators and employed for the synthesis of three different superdirective, two-element antenna arrays with variable interelement spacing. High directivity values are obtained experimentally. The experimental results show that the radiation efficiency of the reported arrays decreases as the interelement spacing of the arrays is reduced. Nevertheless, the directivity increase that is achieved with the interelement spacing reduction compensates the efficiency reduction, enabling even the more compact arrays to deliver reasonable gain values.