Active antenna

About: Active antenna is a research topic. Over the lifetime, 2246 publications have been published within this topic receiving 26493 citations.

Symmetrical antenna structure and a method for its manufacture as well as an expansion card applying the antenna structure

Abstract: An antenna structure which comprises at least one active and at least one parasitic antenna conductor and which is arranged to be fitted on top of a planar electroconductive surface at a distance from said surface which is arranged to be used as a ground plane for said antenna structure, and which antenna structure comprises, arranged parallelly at a distance from each other, a first antenna conductor and a second antenna conductor which have an electrical length of approximately ¼ of the wavelength of the used frequency and which are parallel with said ground plane, and which comprise opposite first ends and opposite free second ends, wherein the antenna structure is equipped with symmetrical conductors for short-circuiting the first ends to said ground plane and a first conductor for coupling the supply to a desired point between the first end and a second end of the active antenna conductor. The antenna structure is symmetrically equipped with also a second conductor for coupling a short circuit to the corresponding point between the first end and the second end of the parasitic antenna conductor in such a way that in the rotated position of 180° of the antenna structure, the second conductor is, in turn, used as said supply and the first conductor is, in turn, used as said short circuit.

Spacecraft with active antenna array protected against temperature extremes

Abstract: A spacecraft carries a deployable active antenna array panel(s) and a deployable solar array panel(s). In the stowed condition, the antenna array panel(s) is sandwiched between a side of the body of the spacecraft and the solar array panel(s). This stowed state prevents the antenna panels from becoming too cold by radiation, or too hot by insolation, in an intermediate orbit. The outermost solar panel preferably has its active surface facing outward, so that it can generate electricity in the intermediate orbit.

Variable synthesized polarization active antenna

Abstract: 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°, 90° or 180° 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.

A Fully Bidirectional 2.4-GHz Wireless-Over-Fiber System Using Photonic Active Integrated Antennas (PhAIAs)

Abstract: This paper describes a low-cost scheme for implementing in-building distributed antenna systems using the photonic-active-integrated-antenna (PhAIA) concept, whereby photonic devices are integrated directly with planar antennas. Deembedded input impedance is measured for an 850-nm vertical-cavity surface-emitting laser and photodiode from 0-10 GHz, and the devices are matched directly to the nonradiating edge of a rectangular-microstrip-patch antenna. Link gain, 1-dB compression point, and spurious-free dynamic range are measured in the links. The fully bidirectional system, which is far from being completely optimized, is then tested over a 300-m laboratory-based multimode fiber link and a 220-m in-building dark-fiber link. Results are shown for throughput and signal-to-noise ratio, and this paper shows that such systems can achieve up to 10-m RF range, at reduced throughput, with no RF amplification.