Régis Guinvarc'h

Dual Polarization Interleaved Spiral Antenna Phased Array With an Octave Bandwidth

A technique to design dual polarization spiral antenna phased arrays using mono polarization spirals is presented. The proposed technique consists of two interleaved subarrays, one for each polarization. The position of every spiral antenna is optimized through a genetic algorithm so that each array is nearly the size of the platform while having low sidelobes. Both resulting arrays have the same properties and are steerable. This method also helps to increase the bandwidth. An 80-element spiral array (spiral of width 0.25 m) with dual polarization is demonstrated, its beam can be steered ±30°, over almost one octave (1.97:1). The physical rejection of the sidelobes (i.e., without weighting) is about - 10 dB.

Dual function radar communication Time-modulated array

This paper introduces the use of Time-modulated array methods to realize a dual function array. It is able to do a radar function in the mainlobe, while realizing a communication in the side lobe.

Optimization of Sparse Time-Modulated Array by Genetic Algorithm for Radar Applications

This letter investigates sparse time-modulated arrays (STMAs). It shows that they provide an efficient solution to achieve specified radiation patterns in radar application with a reduced number of bits to code the weighting coefficients. Interference rejection is also demonstrated.

Study of the radiated polarization of an antenna array with circular geometry

This paper deals with an investigation on the polarization of an antenna array with a circular geometry. The theory shows that the polarization of a circular array exhibits a circular polarization independent of the antenna elements. Circular polarization is then achieved whatever the polarization of the elements of the array. Moreover, due to the circular geometry of the array, the entire far field pattern of the array can be obtained with the measurement or the simulation of only one antenna inside the array. The influence of the array radius on the polarization performances has been investigated. An antenna array has been built, and measurements have been performed in order to corroborate the theoretical results.

Connecting Spirals for Wideband Dual Polarization Phased Array

A technique is presented to design dual polarization spiral antenna phased arrays using mono polarization spirals in an alternating configuration. The proposed technique consists of connecting cross polarized neighboring spirals. Thus, the currents in the arms of one spiral flow into the arms of the adjacent spirals. In addition, the currents transmitted to the neighboring spirals radiate the same polarization, as a center fed spiral and an externally fed cross spiral radiate the same polarization. The optimization of the shape of the connection is also presented. The lowest operating frequency of the new array design is 1.8 times lower than an array of isolated spirals while being dual polarized and steerable .

A Dual-Polarized Wideband Planar Phased Array With Spiral Antennas

The design of a wide bandwidth dual-polarized phased array of Archimedean spiral antennas with cavity is presented. The reflection coefficient, circular polarization and grating lobes are addressed independently in the design process. Uniform concentric rings array is used to control the grating lobes, thanks to its non uniform spatial distribution, and obtain a good circular polarization, thanks to its rotational symmetry. Simulations of one-ring array agree with the measurements. Adding more rings keeps the side lobes level to less than -10 dB, relative to the main lobe. The dual-polarized array can scan up to θ = 30° keeping a low reflection coefficient and low side lobe levels.

180

Reflection-type phase shifters (RTPSs) of 180° and 90° using over-coupled Lange couplers to obtain multioctave bandwidth are presented. A thorough theoretical analysis of the effect of coupler parameters on the RTPS performance is provided. The impact of coupler parameters on the RTPS performance is further illustrated with vector plots. Each measured phase shifter is comprised of an over-coupled Lange coupler, two low-loss single-pole double-throw switches, and two pairs of LC reflection loads on a Rogers RO4003C substrate with a thickness of 0.8 mm (32 mil) and 1.5 mm (60 mil). By using the 1.5-mm substrate, the coupling can be increased. Phase shifts of 90° and 180° using Lange couplers with 2-3-dB coupling in steps of 0.2 dB are designed, fabricated, and measured. The experimental results show that an over-coupling of 2.2 dB is able to obtain a return loss larger than 10 dB over a 127% bandwidth from 550 to 2450 MHz for all states. Worst case measured insertion loss and phase error on the 0.8-mm substrate with an over-coupling of 2.8 dB is 2.0±0.8 dB and ±5.8°, respectively, for both 180° and 90°phase states. On the 1.5-mm substrate with an over-coupling of 2.4 dB, they are 1.8 ±1 dB and ±16°, respectively, for both phase states.

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A low-profile cavity-backed dual-polarized printed spiral antenna array is presented. This spiral array is composed of four center-fed Archimedean spiral antennas printed on FR4 substrate backed by a low-profile cavity without absorbing material. The dual polarization is generated using monopolarized spirals in an alternating configuration right-hand circularly polarized (RHCP) and left-hand circularly polarized (LHCP). These spirals are connected allowing the current to flow from the excited spirals arms into the arms of the neighboring ones. The proposed spiral array provides unidirectional beam while being dual-polarized (LHCP or RHCP) for a wide bandwidth. The dual polarization of the proposed spiral array is extended to low frequencies, and the gain varies up to 13 dBi in the antenna bandwidth. The antenna array performances are presented and validated using electromagnetic simulations and radiation pattern measurements.

and 90

The application of Time-Modulated Array (TMA) to radar is described. Some techniques based on TMA are compared, in terms of capabilities and hardware requirements. It is shown that they permit to keep the main lobe constant which is required for radar. Low sidelobes can be synthesized as well as interference suppression.

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Schelkunoff Multi diagrams (SMD) is a new technique to reduce side lobe level (SLL) in radar application. It consists in applying successive sets of weights to the array elements during the integration time in order to generate an “average” SLL. It is shown that this method permits to synthetize a Chebychev continuous weighting with only 3 bit-coding. Some additional zeros are also placed in the radiation pattern to suppress interference.