Single-layer Slotted Waveguide Array Research Articles

Reduction of Long Line Effects in Single-Layer Slotted Waveguide Arrays With an Embedded Partially Corporate Feed

Single-layer slotted waveguide arrays have various advantages such as low cost and mass productivity for fabrication, high gain and efficiency especially in millimeter wave band. They have traveling wave operation and the bandwidth becomes inherently narrower due to the long line effect as the antenna gain increases. This paper proposes the partially corporate feed in the single-layer structure, which inherits the advantage of low cost in fabrication. The bandwidth enhancement as well as the degradation due to the non radiating area in the aperture is assessed. The feasibility/potential of the embedded partially corporate feed is demonstrated by the experiments using the E- to H-plane power divider with very small blockage.

Analysis and Uniform Design of a Single-Layer Slotted Waveguide Array Antenna with Baffles

This paper presents the formulation for the evaluation of external coupling in the alternating-phase feed single-layer slotted waveguide array antenna with baffles by using the Spectrum of Two-Dimensional Solutions (S2DS) method. A one-dimensional slot array is extracted from the array by assuming the periodicity in transversal direction and introducing the perfect electric conductors in the external region. The uniform excitation over the finite array is synthesized iteratively to demonstrate the fast and accurate results by S2DS. A unit design model with the baffles is introduced to determine the initial parameters of the slot pair which accelerate the iteration. Experiment at 25.3GHz demonstrates good uniformity of the aperture field distribution as well as the effects of the baffles. The directivity is 32.7dB which corresponds to the aperture efficiency 90.5% and the reflection is below -15.0dB over 1.3GHz.

Fabrication of Alternating-Phase Fed Single-Layer Slotted Waveguide Arrays Using Plastic Materials with Metal-Plating

Lightweight single-layer slotted waveguide array antennas are fabricated using plastic materials with metal-plating. A plastic material that has good heat-radiation properties is investigated. Three types of antennas are fabricated by milling, using ABS resin, heat-radiating plastic, and aluminum alloy. In measurements, all three types of antennas are confirmed to have almost the same VSWR and gain in the 25GHz frequency band.

The Ridged Cross-Junction Multiple-Way Power Divider for Small Blockage and Symmetrical Slot Arrangement in the Center Feed Single-Layer Slotted Waveguide Array

The center-feed in a single-layer slotted waveguide array [1]-[3] is one of the key components in polarization division duplex (PDD) wireless systems. Two center-feed arrays with orthogonal polarization and boresight beams are orthogonally arranged side-by-side for transmission and reception, simultaneously. Each antenna has extremely high XPD (almost 50dB in measurement) and a very high isolation (over 80dB in measurement) between two arrays is observed provided the symmetry of slot arrangement is preserved [4]. Unfortunately, the area blocked by the center feed causes high sidelobe levels. This paper proposes the ridged cross-junction multiple-way power divider for realizing blockage reduction and symmetrical slot arrangement at the same time.

“Reduction of Aperture Blockage in the Center-Feed Alternating-Phase Fed Single-Layer Slotted Waveguide Array Antenna by E- to H-Plane Cross-Junction Power Dividers”

The alternating-phase fed single-layer slotted waveguide array antenna, which dispenses with the electrical contact between the narrow walls and the slotted plates, has been developed for low cost wireless communication systems, radar systems, etc. The center-feed is introduced to increase antenna bandwidth by having the long line effects associated with the end-feed one. However, the large blocking area at the center of the array aperture causes high first side-lobe levels (about -10 dB). In this paper, the authors propose a cascade of E- to H-plane cross-junctions as a new single-layer feed waveguide with reduced blockage. It is in single-layer without inductive posts and is mass producible by die-casting techniques. The antenna characteristics and sidelobe reduction are confirmed by simulation and experiment.

An Alternating-Phase Fed Single-Layer Slotted Waveguide Array with a Sector Shaped Beam for Millimeter-Wave Radar Applications

SUMMARY This paper presents design of an alternating-phase fed single-layer slotted waveguide array for a sector shaped beam in the Eplane radiation pattern. A sector beam pattern is very effective for radar applications for detecting obstacles in a certain angular range without mechanical or electronic scanning. The sector shaped beam with 13 degree beam width is synthesized by a cascade of T-junctions in the feed waveguide which excite the radiating waveguides with a longitudinal shunt slot array. In order to realize the required excitation distribution of the radiating waveguides for the sector shaped beam, 30 T-junctions with symmetrical arrangement are designed by tuning a width of the coupling window, an offset of the window, and a width of the feed waveguide cascaded to the subsequent T-junction, respectively. Design and measurement are performed in 60 GHz band. The prototype antenna assembles easily; the slotted plate is just tacked on the groove feed structure and is fixed by screws at the periphery, which is the key advantage of the alternating-phase fed arrays. The measured sector pattern with low sidelobe level agrees well with the predicted one. Validity of the sector beam design as well as the performance

Design of 1 m2 Order Plasma Excitation Single-Layer Slotted Waveguide Array with Conducting Baffles and Quartz Glass Strips Using the GSM-MoM Analysis

The authors have proposed a 1 m 2 single-layer slotted waveguide array consisting of conducting baffles and quartz glass strips positioned in front of the slot aperture, which is referred to as a vacuum window, for microwave plasma excitation. The effect of the complicated outer vacuum window hinders the realization of uniform distribution. In this paper, a unit-cell of the alternating-phase fed single-layer slotted waveguide array with the vacuum window is analyzed by generalized scattering matrix method (GSM)-method of moments (MoM) hybridization analysis, and the array is designed to realize uniform aperture electromagnetic field distribution, where the plasma and the chamber is neglected. The GSM-MoM analysis gives reliable numerical results while the MoM has numerical errors due to singularities of Green's function for a long cavity. Uniform aperture EM field distribution outside of the vacuum window is observed in near field measurements using a 1/5 scale model antenna, and the validity of the analysis and design is verified.

Center Feed Single Layer Slotted Waveguide Array

A center feed configuration is newly introduced to enhance the bandwidth as well as to suppress the frequency dependent beam squinting in single layer slotted waveguide arrays. A multiple-way power divider consisting of cross-junctions is installed at the center of the aperture in an alternating-phase fed waveguide slot array to reduce the long line effect in the radiating waveguide. Each radiating slot is equipped with an inductive wall for reflection canceling, which dispenses with the beam tilting technique for suppressing cumulative reflection and assures the boresight beam. All these are equipped in single layer and are potential for low cost mass-production as is usual the case with alternating phase-fed arrays. The test antenna is fabricated at 26GHz band for FWA system. A 30.5 dBi gain with 46% efficiency with the main beam staying in the boresight is obtained. The sidelobes of -9.5 dB associated with the aperture blockage for the center feed is suppressed to below -14.7 dB at the design frequency, by applying a genetic algorithm for controlling the slot excitation

Feasibility of mechanical beam scan by movable dielectric blocks in the feeder of a single-layer waveguide array antenna

The authors investigate the feasibility of mechanical beam scan by moving dielectric blocks in the feed waveguide of single-layer slotted waveguide arrays. A model using two phase shifters of polycarbonate (er =2.8) is designed and fabricated with three radiating apertures at 12GHz band. 90-degree phase difference is obtained between the adjacent windows to give 11-degree shift of the main beam. Another phase shifter of alumina (er =9.8) gives larger phase shift of 133 degrees corresponding to 15-degree beam tilt.

A Three-Way Divider for Partially-Corporate Feed in an Alternating Phase-Fed Single-Layer Slotted Waveguide Array

In this paper, a three-way divider is proposed for a partially-corporate feed in an alternating phase-fed single-layer slotted waveguide array. The divider is placed at the middle of the feed waveguide and reduces the long line effects; the frequency bandwidth is doubled. It is a kind of cross junction with one input port and three output ports; most of the power is equally divided into the right and left halves of the feed waveguide while the rest of power goes straight into the center radiating waveguide. Based upon the moment method design of the three-way divider, an inductive post is introduced for wide band power dividing control to the radiating waveguide. Reflection is below -20dB over a wide bandwidth of 24.3-26.3 GHz, and the range of power dividing ratio ranges from 1/43 to 1/4. The amplitude and the phase from the two output ports to the feed waveguide are well balanced, and the differences are less than 0.1 dB and 5.0 degrees, respectively. The MoM analysis and the wide band design are verified experimentally in the 4 GHz band.

An Alternating-Phase Fed Single-Layer Slotted Waveguide Array in 76 GHz Band and Its Sidelobe Suppression

This paper presents designs and performances of 76 GHz band alternating-phase fed single-layer slotted waveguide arrays. Two kinds of design, that is, uniform aperture illumination for maximum gain and Taylor distribution for sidelobe suppression of -25 dB, are conducted. High gain and high efficiency performance of 34.8 dBi with 57% is achieved for the former, while satisfactory sidelobe suppression of -20 dB in the H-plane and -23 dB in the E-plane with high efficiency is confirmed for the latter. The simple structure dispensing with electrical contact between the slotted plate and the groove feed structure is the key advantage of alternating-phase fed arrays and the slotted plate is just tacked on the feed structure with screws at the periphery. High gain and high efficiency performances predicted theoretically as well as design flexibility of the alternating-phase fed array are demonstrated in the millimeter wave frequency.

Alternating-phase fed single-layer slotted waveguide arrays with chokes dispensing with narrow wall contacts

An alternating-phase fed single-layer slotted waveguide array consisting of only two components (a slotted plate and a groove feed structure with a choke) is proposed. Its excellent characteristics as well as the mechanical advantage are demonstrated. It dispenses with the electrical contact between two components and is promising for mass production. Two key techniques are introduced. One is the slot design for suppressing the grating lobes and the analysis for evaluating the mutual coupling between slots. The other is a choke on the periphery of the feed structure to dispense with contact of the periphery. A 32.4 dBi gain with 60% efficiency is measured by the choke antenna without electrical contact at 26 GHz. This is an excellent result which is comparable to the full-contacted model. The advantages of alternating-phase fed arrays for mass production are now fully confirmed.

Design and analysis of a single-layer slotted waveguide array

Design and analysis of a single-layer slotted waveguide array

Single-Layer Slotted Waveguide Arrays for DBS Reception and Higher Frequency Applications

Increasing demands for high-gain and high-efficiency planar antennas in higher frequencies are surveyed. Firstly, waveguide structures suitable for planar arrays are compared. Several types of single-layer slotted waveguide arrays are proposed and their high potentials in terms of efficiency and mass produceability are demonstrated in 10 to 20 GHz band such as DBS reception. The applicability to millimeter wave frequencies up to 60GHz band is demonstrated.

Alternating phase-fed waveguide slot arrays with a single-layer multiple-way power divider

Single-layer slotted waveguide arrays consist of two parts, the slot plate and the groove feed structure of waveguides. The key difficulty in their mass production is the realisation of perfect electrical contact between the two parts. The paper presents a single-layer feed circuit consisting of T-junctions which divides an input power into all the radiating waveguides in alternating phase; it dispenses with the electrical contact in principle. Experiments confirm the waveguide design of a power divider and the feasibility of an alternating phase-fed single-layer slot array is also demonstrated.

High-gain and high-efficiency single-layer slotted waveguide array for use in 22 GHz band

A slotted waveguide planar array using a single-layer feed circuit is proposed for high-frequency and high-gain antennas. The high efficiency of 75.6% and the gain of 35.9 dBi are obtained in the 22 GHz band, which confirms the potential of this type of antenna. The antenna consists of only two components, a slotted plate and a groove feed structure, and can be mass produced.

A single-layer slotted leaky waveguide array antenna for mobile reception of direct broadcast from satellite

This paper proposes a single-layer slotted leaky waveguide array antenna for mobile DBS reception. A single-layer feed structure is proposed, where the feed waveguide is in the same layer as the radiating waveguides. This results in the simple fabrication of slotted waveguide arrays, suitable for mass production. Short radiating leaky waveguides are used to get a large beam-tilting angle of about 50/spl deg/ for the horizontal installation of the antenna and a beamwidth broad enough to dispense with mechanical steering in the elevation plane. A prototype antenna sized 30 cm by 21 cm has a maximum of 74% efficiency and more than 69% efficiency within the DBS band. It also has a broad l-dB beamwidth of 7.5/spl deg/ in the elevation plane, which enables clear DBS reception by a picture tube display over about one-third the area of Japan without elevation tracking.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>