Topic
Reflective array antenna
About: Reflective array antenna is a research topic. Over the lifetime, 4366 publications have been published within this topic receiving 57884 citations.
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Patent•
22 Oct 2003TL;DR: In this paper, the two radar sensors are switchable with reference to their main beam direction as well as their beam width for an angle-resolving antenna system, including separate transmitting and receiving antennas.
Abstract: For an angle-resolving antenna system, only two radar sensors are provided including separate transmitting and receiving antennas. The receiving antennas of the two radar sensors are switchable with reference to their main beam direction as well as to their beam width.
54 citations
TL;DR: Results in the single antenna studies showed that the dipole was less affected by snugness of catheter fit than the multisection, hot-tip or helical antennas, and in large catheters, the latter three antennas showed more extreme tip heating performance.
Abstract: Interstitial techniques of inserting catheters into tumors for the purpose of applying therapeutic irradiation and hyperthermia are in widespread use. Several miniature microwave antenna designs are currently used for these treatments. These include multisection, hot-tip, 2- and 3-node, dipole and helical antennas, all of which are commercially available. The antenna designs are diverse enough to have a dramatic effect on the power deposition patterns either as single antennas or when used in arrays. Aside from the dipole antenna, most of the antennas have never been evaluated experimentally or theoretically in arrays, although the array configuration is used in the vast majority of all clinical treatments. Power deposition or SAR (specific absorption rate) tests were run in muscle equivalent phantom. Single antennas were evaluated at 400 points in a plane and isoSAR contours drawn, normalized to maximum SAR. Single antennas were also compared in large and small diameter catheters to evaluate catheter dependent antenna performance. The dipole, multisection, hot-tip and helical antennas were evaluated in arrays of four antennas located at the corners of a square, spaced 2.0 cm apart. Arrays of antennas were evaluated at 441 points in three planes orthogonal to the antenna axes. Results in the single antenna studies showed that the dipole was less affected by snugness of catheter fit than the multisection, hot-tip or helical antennas. In large catheters, the latter three antennas showed more extreme tip heating performance. The 2- and 3-node antennas deposited only 20% SAR in the distal 30 mm of antenna length. In arrays, the multisection, hot-tip, and dipole antennas all yielded 80–90% SAR centrally in the central measurement plane. Comparing the three antennas, the dipole array deposited 20% more power centrally in a plane near the insertion point, and the multisection and hot-tip antenna designs deposited 10% more central power in a plane near the antenna tips. The helical antenna array deposited only 30% SAR centrally in the plane near the antenna tips and in the central plane. Only 10% SAR was measured centrally near the insertion point, as expected for tip-heating antennas. Finally, the clinical significance of the results is discussed as applied to human tumors undergoing hyperthermia treatments.
54 citations
Patent•
NEC1
TL;DR: In this article, a dual-band antenna apparatus with a plurality of first-phase antenna elements for low frequency and a plurality-of-second-phase array antennas for high frequency was presented.
Abstract: In a dual band array antenna apparatus having a plurality of first phased array antenna elements for a low frequency and a plurality of second phased array antenna elements for a high frequency, one transceiver module is provided for a number of the phased array first antenna elements, and microstrip lines of the first phased array antenna elements are changed to obtain a desired phase distribution at the first phased array antenna elements Also, one transceiver module is provided for each of the second phased array antenna elements
53 citations
TL;DR: In this article, the authors developed ANETs for two applications: (1) to serve as elements in radiating systems of localizers and radio ranges used to guide aircraft; (2) to act as receiving antennas carried by aircraft.
Abstract: ANTENNAS which are discussed in this paper were developed for two applications: (1) to serve as elements in radiating systems of localizers and radio ranges used to guide aircraft; (2) to act as receiving antennas carried by aircraft.
53 citations
TL;DR: It is shown that by increasing the element spacing of an array the directional error rate characteristics of the system, in a given direction, can be significantly improved and the directly modulated system shows superior error rate performance to that of an equivalent, conventionally modulated, system in the grating lobe directions.
Abstract: A new approach to enhance the security of data transmission using direction dependent antenna modulation based on an array with wide element spacing combined with directional array elements is presented. For illustrative purposes, the system investigated, and reported here, consists of an array of only two elements but the approach is general and can be extended to multi-element array systems. It is shown that by increasing the element spacing of an array the directional error rate characteristics of the system, in a given direction, can be significantly improved. Furthermore, the directly modulated system shows superior error rate performance to that of an equivalent, conventionally modulated, system in the grating lobe directions. The error rate characteristics of the proposed system are analysed for two scenarios: firstly when the angular separation between an eavesdropper and the intended recipient is small and secondly for the case when a potential eavesdropper is located much closer to the transmit antenna than the intended recipient.
53 citations