Frequency-independence and symmetry properties of corrugated conical horn antennas with small flare angles Citation for published version (APA): Jeuken, M. E. J. (1970). Frequency-independence and symmetry properties of corrugated conical horn antennas with small flare angles. [Phd Thesis 1 (Research TU/e / Graduation TU/e), Electrical Engineering]. Technische Hogeschool Eindhoven. https://doi.org/10.6100/IR56990 DOI: 10.6100/IR56990 Document status and date: Published: 01/01/1970 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please follow below link for the End User Agreement: www.tue.nl/taverne Take down policy If you believe that this document breaches copyright please contact us at: [email protected] providing details and we will investigate your claim. Download date: 22. Jan. 2023 FREQUENCY -INDEPENDENCE AND SYMMETRY PROPERTIES OF CORRUGATED CO NI CAL HORN ANTENNAS WITH SMALL FLARE ANGLES .. M.E.J. JEUKEN FREQU ENCY -INDEPENDENCE AND SYMMETRY PROPERTIES OF CORRUGATED CON IC AL HORN ANTENNAS WITH SMALt FLARE ANGLES PROEFSCHRIFT TER VERKRIJGING VAN DE GRAAD VAN DOCTOR IN DE TECHNISCHE WETENSCHAPPEN AAN DE TECHNISCHE HOGESCHOOL TE EINDHOVEN OP GEZAG VAN DE REC TOR MAGNIFJCUS PROF.DRJR.A.A.Th.M. VAN TRIER, HOOGLERAAR IN DE AFDELING DER ELECTROTECH NIEK, VOOR EEN COMMISSIE UIT DE SENAAT TE VER DEDIGEN OP DINSDAG 8 SEPTEMBER 1970, DES NAMID- DAGS TE 4 UUR. DOOR MARTINUS ELISABETH JOHANNES JEUKEN GEBOREN TE VENRAY GREVE OFFSET N .V. EINDHOVE:-1 Dit proefschrift is goedgekeurd door de promotor Prof.Dr.Ir.A.A.Th.M. van Trier een aandenken aan mijn vader aan mijn moeder aan mijn vrouw This work was performed as a part of the research program of the group Theoretical Electrical Engineering of the Eindhoven University of Technology, Eindhoven, the Netherlands. CONTENTS Chapter Feeds For Reflector Antennas I. I Introduetion 7 1.2 Survey of the recent literature concerning feeds 10 1.3 Pormulation of the problem 13 Chapter 2 Frequency-Independent Conical Horn Antenna 2.1 The radiation pattarn of a horn antenna IS 2.2 Theory of frequency-independent conical horn an 25 tennes 2.3 Experimental investigation of the power radia 45 tion pattern of a frequency-independent conical horn antenna with a small flare angle 2.4 Theory of the equiphase surfaces of a frequency 57 independent conical horn antenna with a small flare angle 2.5 Experimental investigation of the phase radia 65 tion pattarn of frequency-independent conical hom antenna with a small flare angle Chapter 3 Conical Horn Antennas With Symmetrical Radietion Pattarn 3. I Circular aperture with symmetrical radiation 75 pattern 3.2 Propagation of waves in a circular cylindrical 86 waveguide with anisotropic boundary 3.3 Power radiation pattarn of an open circular wave lOl guide with anisotropic boundary 3.4 Circular corrugated waveguide 107 3.5 The power radiation pattem of corrugated conical 114 hom antennas with small flare angle and small aperture 3.6 Theoretica! investigation of frequency-independent 120 conical hom antenna with small flare angle and anisotropic boundary 3.7 Experimental investigation of frequency-independent 124 corrugated conical hom antenna with smal! flare angle Appendix A 131 Appendix B 133 S1lllllllary 138 Samenvatting 140 Raferences 143 Acknowledgements 147 Levensbericht 148 CHAPTER l FEEDS FOR REFLECTOR ANTENNAS 1.1 Introduetion The parabolic reflector is a popular antenna in the microwave region. This is the frequency range from. 1 GHz to 300 GHz. In this range the parabolic reflector is used as an antenna for radar, line-of-sight communications, satellite communications and as an instrument for radio-astronomical investigations. The principle of this reflector antenna is that a spherical wave de parts from the focal point of the parabola towards the reflector, which reflects the wave and concentratas a large part of the energy in a small angle along the axis of the parabola. As a souree of the sphe rical waves use is mostly made of a small horn antenna. Such a souree is called a feed. It is obvious that the performance of the reflector antenna depends mainly on the feed used. For instance, the illumination of the reflector and the spill-over energy along the rim of the reflector depend on the radiation pattern of the feed. It is well-known that for a reflector antenna no unique definition of the bandwidth can be given [1]. However, generally speaking, we can say that the bandwidth of a reflector antenna is chiefly determined by the properties of the feed. The precise requirements which have to be satisfied by the feed depend on the application for which the antenna will be used. Let us summarise the most relevant properties of the feed in the four applications mentioned at the beginning of this section. For a radar antenna a high gain is necessary, because the range of a radar system is proportional to the square root of the antenna gain. This high gain can be obtained if a reflector antenna is used with a diameter, which is large compared with the wavelength. Moreover, one should choose the illumination of the reflector in such a way that a high efficiency is obtained. This requirement implies that the illu mination should be as uniformly as possible and the spill-over energy along the rim of the reflector as low as 'possible. A radiation pattem 7 ·with these two properties is called a sector shaped radiation pattern. The radiation pattem of a conventional feed, such as an open radia ting waveguide, deviates considerably from a sector shaped radiation pattern. Therefore modern research on feeds is mainly carried out with the aim to improve the radiation pattern of conventional feeds. For a radar antenna it is sufficient that the feed possesses a sector shaped radiation pattern in a rather small frequency range, because the band width of a radar antenna is small. In addition, sometimes a· radar antenna should transmit and receive circularly polarised waves in order to prevent the detection of echoes from such targets as rain and snow [1]. It is clear that in this case the feed should be able to transmit and receive circularly polarised waves without disturbing the other properties discussed above. An antenna for line-of-sight communications should meet the same high requirement with regard to the gain as a radar àntenna. The bandwidth of this antenna system is much larger, because the antenna is used for telephone and T.V. traffic. In the frequency spectrum above I GHz sev eral frequency bands have been allocated for this kind of communica tions. Which of the frequency bands mentioned above are used in a, line-of-sight communication system depends on the local situation. In order to use the frequency bands as effectively as possible the feed must be suitable for operation in two perpendicular modes of po larisation [2]. In that case it is very desirabie that the radiation patterns in two perpendicular planes are the same for the two modes of polarisation. It is obvious that a symmetrical radiation pattern with respect to the antenna axis meets this requirement. One of the most recent applications in the microwave field is communi cation by means of satellites, for instance, the famous Early Bird (= Intelsat I), Intelsat II and Intelsat III and in the near future the Intelsat IV, which are employed for intercontinental telephone and T.V. traffic. Again the antenna for satellite-communications should be suitable for braadband operation, because of the large amount of information that must be handled with this system. In order to get an idea about the bandwidth which is required in these modern communication systems, it should be noted that a groundstation used for communications with Intelsat III must be suitable for in the frequency band 3700- 4200MHz and transmitting in the 5925- 8