摘要:
A transmit and/or receive array antenna comprises an array (R) of sub-arrays (SR) of at least one radiating element (ER) and control means charged with controlling the amplitude and/or the phase of the radiofrequency signals to be transmitted or received in the form of waves by each of the sub-arrays (SR) so that they transmit or receive signals according to a chosen pattern. The sub-arrays (SR) comprise a mean number of radiating elements (ER) which increases from the center of the array (R) to its periphery, and are arranged with respect to one another so as to constitute an irregular mesh offering pattern sidelobes of low intensity and a high gain in a favored direction.
摘要:
In a method of calibrating an active antenna the active elements of a transfer function matrix are measured using a near field probe for each radiating source of the antenna. The probe is placed in front of each source in succession and each source is excited in turn with the opposite phase and with all the other sources of the array excited normally. In the case of linear superposition of radiated fields, the measurements obtained by this method yield the elements of the transfer function matrix directly. This allows for phase and amplitude errors due to the components of the active antenna and for the effects of coupling between adjacent sources which modify the theoretical characteristics of the antenna. In the non-linear case the measurements are repeated and the matrix is obtained by iteration based on a comparison of the theoretical values used to control the antenna and the measured fields actually obtained. Measurements carried out on individual active modules prior to assembly of the antenna can be used in one variant of the method.
摘要:
A high-efficiency active printed-circuit antenna system for pulsed frequency-hopping space radar electronically scanned in two planes encompasses in its timing diagram the transmission of a horizontal polarization pulse, the reception of echoes from a previous horizontal polarization pulse, the transmission of a vertical polarization pulse and the reception of echoes from a previous vertical polarization pulse. The system comprises several thousand MMIC modules distributed over the antenna and each connected to a printed-circuit radiating element comprising a plurality of dual polarized square patches connected by microstrip lines which excite them with the same amplitude and the same phase at two perpendicular ports. Switching between the two ports procures transmission or reception with horizontal or vertical polarization.
摘要:
A method of forming the radiation pattern of a high efficiency active antenna for electronically-scanned radar, wherein its illumination laws, and thus its radiation patterns are dissociated in transmission and in reception; and equal amplitude illumination is provided in transmission in order to maximize the efficiency of the transmit amplifiers which are all identical, thereby minimizing their DC energy consumption and their dissipation. The invention is particularly suitable for use in space radars.
摘要:
A reflector network antenna (A) comprising i) a source (S) delivering wave signals; ii) at least two reflector networks (RR1-RR9) which are different and independent and which both comprise at least two phase shifter cells which selectively phase shift the waves delivered by the source (S) and bring about a selected frequency phase dispersion thereof, said selective phase shifting and selective dispersion varying from one reflector network to another; and iii) a charging device (DC) which is coupled to the reflector networks (RR1-RR9) and which is used to place one of them in a selected position in relation to the source (S) such that the waves that it delivers are phase shifted and phase dispersed at a frequency imposed by said phase shifter cells in order to be reflected in a selected direction.
摘要:
An electronically-scanned two-beam antenna designed for being installed on board a moving platform, and in particular a satellite. The antenna of the invention comprises a single, complex reflector whose reflectivity is responsive to the polarization with which it is illuminated, and associated with two arrays of orthogonally-polarized sources that illuminate the complex reflector using an offset configuration. The complex reflector is made up of two reflectors placed one in front of the other in the beam propagation direction. The first reflector is transparent to a first linear polarization and reflective to an orthogonal polarization, while the second reflector is reflective at least for the first polarization. The two resulting beams thus propagate in different directions, both parallel to the trajectory of the platform. Electronic scanning is provided in a plane perpendicular to the orbit plane. The invention is applicable to stereoscopic radars for observing the earth from a satellite, and also to radiometry.
摘要:
The invention concerns a microwave transmit/receive (T/R) circuit for a polarization synthesizer array antenna, especially a radar antenna. According to the invention the required polarization is obtained by applying two signals to an array element on two orthogonal feed paths with a variable phase difference between the two paths, both of which function simultaneously. In a preferred embodiment both transmit channels are provided with two power amplifiers which each amplify a signal from an in-phase power divider or a hybrid coupler, with a one-bit or two-bit controllable phase-shifter adding a phase-shift of 0.degree., 90.degree. or 180.degree. to synthesize orthogonal linear or circular polarizations. In a preferred embodiment the circuit according to the invention is partly or entirely implemented in monolithic (MMIC) technology. The invention also concerns an antenna including a T/R circuit as specified hereinabove.
摘要:
A phase shifter module (PSM), dedicated to a reflectarray antenna, is defined by a characteristic resonant length and, in at least one chosen place, has an MEMS type device (SD, SD′) able to be placed in at least two different states respectively permitting and prohibiting the establishing of a short-circuit intended to vary said resonant length, in order to vary the phase shifting of a wave to be reflected presenting at least one linear polarization.
摘要:
A transmission relay system includes a receive antenna with first radiating elements, a transmit antenna with second radiating elements, and processing devices through which the first radiating elements and the second radiating elements are connected. The processing devices are in the form of processing systems all of which induce the same propagation time-delay. Each system connects a given first radiating element to a corresponding given second radiating element defined firstly by an angular position relative to a second axis of symmetry specific to the transmit antenna offset substantially 180.degree. relative to an angular position of the given first radiating element relative to a first axis of symmetry specific to the receive antenna and parallel to the second axis of symmetry and secondly by an eccentricity in the transmit antenna which is a function of an eccentricity of the given first radiating element in the receive antenna.
摘要:
A microwave array antenna comprises a plurality of like unit sources whose width increases progressively from the center of the array towards its ends and which are disposed relative to each other in such a way that substantially no illumination gaps are created in the array.