Topic
Active antenna
About: Active antenna is a research topic. Over the lifetime, 2246 publications have been published within this topic receiving 26493 citations.
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TL;DR: In this article, two modifications to a rectangular-patch antenna, suitable for the integration of active devices, are presented, which allow optimal matching of the active device by changing the position, width, and length of the impedance-line transformer.
Abstract: Two modifications to a rectangular-patch antenna, suitable for the integration of active devices, are presented. In the first modification, the impedance inverter was placed in the rectangular opening formed by removing the central part of the patch. This modification allows optimal matching of the active device by changing the position, width, and length of the impedance-line transformer. An oscillating antenna, using this modified patch and a Gunn diode, showed a high EIRP, higher spectral purity, and substantially lower cross-polarization levels, in comparison with the reference active antenna with an unmodified patch. Because of the higher overall Q, this modification is recommended for active-antenna applications with active devices that have a narrower negative-resistance bandwidth. In the second modification, an active device (Gunn diode) was integrated directly into a rectangular opening inside the patch, without the use of a line transformer. This reduced the overall Q of the antenna, thus allowing wide-band frequency tuning by changing the bias voltage. A clear spectrum, with no spurious components of the free-running oscillating antenna, was observed. Radiation patterns in the E and H planes were measured. Low levels of cross-polarization, as for the first modification, were obtained. Injection-locking properties were investigated throughout the tuning range. A relatively wide locking range, with a good locking gain, was achieved. Such a miniaturized wide-band VCO antenna is applicable for integration in injection-locked active arrays, and spatial power combiners.
20 citations
Patent•
02 Jan 2013
TL;DR: In this paper, a test method and a device for wireless indexes of an active antenna system are presented, where an over-the-air (OTA) test is used for testing spatial characters of the active antenna systems and a near field coupling test device is used to test radio frequency indexes of the system.
Abstract: The invention discloses a test method and a device for wireless indexes of an active antenna system. An over the air (OTA) test is used for testing spatial characters of the active antenna system and a near field coupling mode is used for testing radio frequency indexes of the active antenna system. The invention also provides a near field coupling test device which is a radio frequency testing cover. By the aid of the near field coupling test device, the radio frequency index test can be conducted to the active antenna system which is an integral device of an antenna and a multi-channel transceiver under the condition that any extra test interfaces are not required to be added. According to the comprehensive test method, the advantages of the OTA test and the near field coupling mode are combined fully, the defects and the problems of the OTA test and the near field coupling mode are overcome, and the test efficiency and the test cost are optimized.
20 citations
Patent•
27 May 2010
TL;DR: In this paper, a ground sheet, a feed conductor, and an active antenna branch electrically coupled to the feed conductor are considered. But the active and parasitic antenna branches may be spaced apart.
Abstract: A communications structure may include a ground sheet, a feed conductor, and an active antenna branch electrically coupled to the feed conductor. A parasitic antenna branch may be electrically coupled to the ground sheet, and the active and parasitic antenna branches may be spaced apart. Moreover, the parasitic antenna branch may be between portions of the active antenna branch and the ground sheet.
20 citations
TL;DR: A review of some of the recent developments in the field of millimeter-wave antennas and some details of a specific antenna for imaging are given, illustrating the benefits and challenges of fabricating such antennas.
Abstract: With the continually increasing demand for bandwidth, and the development of components for higher and higher frequencies, millimeter-wave systems are finding numerous applications of a commercial nature rather than being limited to military and scientific applications only. Since active device performance deteriorates with increasing frequency, the performance of the antenna becomes critical as we go higher into the millimeter-wave band. This paper presents a review of some of the recent developments in the field of millimeter-wave antennas. Finally, some details of a specific antenna for imaging are given, illustrating the benefits and challenges of fabricating such antennas.
20 citations
12 Sep 1994
TL;DR: The authors show that the use of a straight antenna always makes it possible to localise the contact point irrespective of friction at the point of contact.
Abstract: This paper addresses a new active sensor system (Active Antenna) motivated by insect's antenna. The antenna can be characterized by its "flexibility" and "active motions". Based on these observations on insect's antenna, the authors' discuss an active sensor system composing of only four components, an insensitive flexible antenna, a position sensor, a torque sensor, and an actuator. The authors first consider the conditions which allow localisation of any contact point between the insensitive flexible antenna and environment by applying an active motion to the antenna. The authors show that the use of a straight antenna always makes it possible to localise the contact point irrespective of friction at the point of contact. The authors also show that contact point sensing by the use of a circular shaped antenna is weakly influenced by the friction at the point of contact. >
20 citations