Wed, 09 Jul 2008 13:37:45 BST CiteULike: dcastros annular http://www.citeulike.org/user/dcastro/tag/annular CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dcastro/article/2938447 <i>Microwaves, Antennas and Propagation, IEE Proceedings -, Vol. 142, No. 2. (1995), pp. 151-155.</i><br /><br />An experimental study of microstrip ring antennas suitable for use in mobile communication systems is presented. Conical radiated beams are generated by the TM₂₁ and TM₄₁ modes. Dual mode concentric rings have been designed which switch the beams in elevation as the vehicle traverses up and down hills or changes latitude within a continent, while maintaining omnidirectional azimuth coverage to optimise signal reception. The authors have successfully designed and tested a stacked array which gives beam coverage in elevation from 20° to 60° with a gain >6 dBi. Mode switched antennas are a cheap and viable alternative to an expensive phased array antenna with continuous beam steering. Various feeding techniques have been investigated for exciting these modes. Bandwidths of 5% or more were attained for each mode. Coaxial probes gave good coupling efficiency and, with the addition of impedance compensating cylinders, bandwidths of 11% and 5% for the TM₂₁ and TM₄₁ modes, respectively, were obtained. Electromagnetic coupling provided a less mechanically complex feed system and control over the input impedance via the length of the feed overlap under the patch. Bandwidths of 7% were obtained for both modes and the resonant frequency was tunable by about 6% by varying the feed overlap length Microstrip ring antennas operating at higher order modes for mobile communications JC Batchelor RJ Langley Microwaves, Antennas and Propagation, IEE Proceedings -, Vol. 142, No. 2. (1995), pp. 151-155. 2008-06-28T00:43:31-00:00 1995 Microwaves, Antennas and Propagation, IEE Proceedings - 142 2 151 155 annular antenna microstrip mobile patch ring http://www.citeulike.org/user/dcastro/article/2858739 <i>Antennas and Propagation, IEEE Transactions on, Vol. 47, No. 2. (1999), pp. 384-388.</i><br /><br />This paper presents calculated and measured results for the input impedance and radiation performance of probe-fed printed annular ring antennas. Geometries featuring stacked rings as well as shorting posts are considered. A numerical model is presented that is based on a full-wave spectral-domain moment-method solution. In this solution, a specialized attachment mode-expansion function is used to model the connection between the probe feed and the printed ring. Measured results are presented and compare well with the theory. Annular rings are found to have certain advantages over circular and rectangular microstrip antennas Rigorous analysis of probe-fed printed annular ring antennas DM Kokotoff JT Aberle RB Waterhouse doi:10.1109/8.761079 Antennas and Propagation, IEEE Transactions on, Vol. 47, No. 2. (1999), pp. 384-388. 2008-06-03T10:49:08-00:00 1999 Antennas and Propagation, IEEE Transactions on 47 2 384 388 annular antenna patch ring http://www.citeulike.org/user/dcastro/article/2187934 <i>Antennas and Propagation, IEEE Transactions on [legacy, pre - 1988], Vol. 33, No. 4. (1985), pp. 369-374.</i><br /><br />Input impedance and bandwidth of an annular ring microstrip antenna have been determined by modeling the antenna as a section of radial line loaded with wall admittances. The effect of mutual coupling between the radiating apertures has been taken into account. The theoretically calculated values of input impedance for TM<inf>12</inf>-mode are compared with measurements. The agreement is good. Higher order modes have been found to be present in the vicinity of TM<inf>12</inf>-mode. The reactance due to these modes can be utilized to increase the voltage standing-wave ratio (VSWR) bandwidth of the antenna. Input impedance of annular ring microstrip antenna using circuit theory approach A Bhattacharyya R Garg Antennas and Propagation, IEEE Transactions on [legacy, pre - 1988], Vol. 33, No. 4. (1985), pp. 369-374. 2008-01-02T12:19:07-00:00 1985 Antennas and Propagation, IEEE Transactions on [legacy, pre - 1988] 33 4 369 374 annular antenna circuit impedance microstrip patch ring http://www.citeulike.org/user/dcastro/article/2187929 <i>Antennas and Propagation, IEEE Transactions on [legacy, pre - 1988], Vol. 30, No. 5. (1982), pp. 918-922.</i><br /><br />A heuristic discussion of the radiation properties of the transverse magnetic (TM<inf>11</inf>) and (TM<inf>12</inf>) modes of the annular-ring microstrip antenna is presented, indicating the possibility of the TM<inf>12</inf>mode as a superior microstrip antenna. Rigorous analyses of the resonant frequency characteristics of the antenna are then performed with the matched asymptotic expansions technique and the perturbation approach. The analyses show that the TM<inf>12</inf>mode is decidedly the best mode for microstrip antenna applications while the TM<inf>11</inf>mode, having a high<tex>Q</tex>-factor, is best reserved for resonator applications. The analyses include the study of the resonant frequencies, bandwidths, and radiation pattern of the antenna. The matched asymptotic expansions technique and the perturbation approach are also shown to agree excellently with each other within their domain of validity. A broad-band annular-ring microstrip antenna Weng Chew Antennas and Propagation, IEEE Transactions on [legacy, pre - 1988], Vol. 30, No. 5. (1982), pp. 918-922. 2008-01-02T12:17:56-00:00 1982 Antennas and Propagation, IEEE Transactions on [legacy, pre - 1988] 30 5 918 922 annular antenna broadband microstrip patch ring http://www.citeulike.org/user/dcastro/article/2187915 <i>Applied Electromagnetics and Communications, 2003. ICECom 2003. 17th International Conference on (2003), pp. 189-192.</i><br /><br />This paper presents a review of the most important features of the shorted annular patch antennas. These radiators have several mechanical and electrical advantages with respect to other microstrip geometries. In particular, the presence of the short in the central zone of the antenna provides increased radiation flexibility which permits to control the antenna beam aperture. In order to demonstrate the usefulness of SAP's features examples of applications in space environment are provided. Shorted annular patches as flexible antennas for space applications L Boccia G Amendola G Di Massa doi:10.1109/ICECOM.2003.1290986 Applied Electromagnetics and Communications, 2003. ICECom 2003. 17th International Conference on (2003), pp. 189-192. 2008-01-02T12:13:15-00:00 2003 Applied Electromagnetics and Communications, 2003. ICECom 2003. 17th International Conference on 189 192 annular antenna patch ring shorted space