A 77-GHz transmit-array on dual-layer printed circuit board (PCB) is proposed for automotive radar applications. Coplanar patch unit-cells are etched on opposite sides of the PCB and connected by through-via. The unit-cells are arranged in concentric rings to form the transmit-array for 1-bit in-phase transmission. When combined with four-substrate-integrated waveguide (SIW) slot antennas as the primary feeds, the transmit-array is able to generate four beams with a specific coverage of $\pm 15^{\circ}$ . The simulated and measured results of the antenna prototype at 76.5 GHz agree well, with gain greater than 18.5 dBi. The coplanar structure significantly simplifies the transmit-array design and eases the fabrication, in particular, at millimeter-wave frequencies.

77-GHz Dual-Layer Transmit-Array for Automotive Radar Applications

This article describes the design of planar transmit-arrays at 10 GHz with 1-bit and 2-bit phase quantization and specific unit-cell designs in each case. The influence of the main design parameters are investigated numerically. The measured directivity/gain values equal 26/23.6 dBi for the 1-bit design, and 23.7/14.3 dBi for the 2-bit design, respectively. In particular, the influence of the unit-cell size is highlighted. Both designs are built on a two-layer printed circuit board assembly and operate in linear polarization. Beam-steering characteristics up to ±30° are investigated and compared by tilting the feed source and by changing the phase distribution across the array.

https://www.piers.org/piersonline/pdf/Vol5No8Page731to736.pdf

Design and demonstration of 1-bit and 2-bit transmit-arrays at X-band frequencies

This article presents the design and characterization of new planar transmit-arrays at 10 GHz with 1-bit and 2-bit phase quantization and specific unit-cell designs in each case. Both arrays are built on a two-layer printed circuit board assembly and are illuminated by a linearly-polarized horn antenna. The 1-bit and 2-bit arrays operate in linear and circular polarization, respectively. The measured directivity/gain values equal 26.2/23.2 dBi for the 1-bit design, and 27.8/24.8 dBi for the 2-bit design. Beam-steering characteristics up to ±30° are achieved by tilting the focal source.

X-band transmit-arrays with linear and circular polarization

This article presents the design, realization and experimental characterization of a new planar transmit-array at 9.6 GHz with a 10% −3dB gain bandwidth. The elementary cell consists of two slot-coupled patch antennas connected with a phase delay line. The design and optimization procedure are presented, as well as experimental results showing an acceptable agreement with the numerical predictions. Beam-steering up to 30° is demonstrated by shifting the feed source. This work is a first step toward the development of future reconfigurable transmit-arrays.

Design and demonstration of an X-band transmit-array

This paper deals with a 2-bit phase quantization (0°/90°/180°/270°) unit-cell for passive transmit-array applications at 10 GHz. The unit-cell consists of a single ground plane, two identical substrates, and two rectangular patch antennas connected by a metallized via hole. We first present the architecture of the unit-cell and an equivalent lumped-element circuit model based on analytic formulas. Their performance is also evaluated by full-wave simulations. To validate the operation principle, several unit-cell prototypes have been manufactured and tested in a waveguide simulator. Finally, one-dimensional beam-steering using 20×20 unit-cells transmit-arrays is demonstrated in linear- and circular-polarization.

Design and characterization of 2-bit passive unit-cells and transmit-arrays in X-band

Planar arrays are a very interesting option to substitute reflector antennas because of their well-known characteristics of low profile, potential low cost, reliability and flexibility in achieving contoured beams and multiple beams with a simple planar geometry. Suitable solutions using planar antennas for space applications have been proposed using reflect-arrays with countered beams and multibeam. Another proposed solution consists of transmit arrays. In this case, the antenna acts as a lens [1]. This consists of a periodic planar array having two patch antennas connected by a line. One element receives the signal from –z direction and the other transmits the signal in the +z direction. By a proper selection of the phase delay in the connection line, the phase distribution in the transmitting array can be adjusted. In an equal output phase configuration the transmitting array behaviour would be similar to the obtained with a parabolic reflector, having the advantage of removing the feed blockage.

A X-Band Planar Transmit-Array

A shaped-beam reflectarray based on aperturecoupled elements is demonstrated as central station antenna for Local Multipoint Distribution System (LMDS) in the 10.10- 10.70 GHz band. The antenna must cover a 60° sector in azimuth with a squared cosecant pattern in elevation. The design process consists of two steps. First, a phase-only pattern synthesis technique is applied to obtain the required phase-shift distribution on the reflectarray surface which generates the shaped pattern. The second stage consists of determining the length of the delay lines, aperture-coupled to the squared patches, in order to achieve the phase distribution synthesized in the previous step. A reflectarray antenna has been designed for vertical (V) polarization. A breadboard has been manufactured and tested in an anechoic chamber, showing a good agreement between theoretical and measured radiation patterns.

Reflectarray para Estación Base LMDS Basado en Parches Acoplados por Apertura

In this work, the authors compare two designs of reflectarray antennas made of two different types of elements. One of the reflectarray designs is intended to generate a collimated beam and the other is intended to generate a contoured beam. In order to produce these radiation patterns, in one case three coplanar parallel dipoles are used as reflectarray elements, and in the other case stacked square patches are used as reflectarray elements. The results obtained indicate that the collimated beam and shaped beam reflectarrays made of parallel dipoles have a good bandwidth performance, which is comparable to that of the collimated beam and shaped beam reflectarrays made of stacked patches. However, the reflectarrays made of parallel dipoles achieve the broadband goal with a manufacturing process that is easier and cheaper than that required by the reflectarrays made of stacked patches.

Francisco Eduardo Carrasco Yépez

Papers

A X-Band Planar Transmit-Array

Reflectarray para Estación Base LMDS Basado en Parches Acoplados por Apertura

Estudio del ancho de banda de 'reflectarrays' diseñados con dos tipos de elementos: dipolos coplanares paralelos y parches apilados