Basic Antenna - Basic Antenna Principles for Mobile...

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Basic Antenna Principles for Mobile Communications Dipl. Ing. Peter Scholz KATHREIN-Werke KG Anton-Kathrein-Straße 1 83004 Rosenheim
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1. Introduction P- 3 2. Theory 4 3. Definitions 5 3.1 Polarization P - 5 3.2 Radiation Pattern P - 5 3.3 Half-Power-Beam-Width P - 5 3.4 Gain P - 6 3.5 Impedance P - 6 3.6 VSWR/Return Loss P - 6 3.7 Mechanical features P - 6 4. Base Station Antennas 7 4.1 Omnidirectional Antennas P - 7 4.1.1 Groundplane and λ /4-Skirt Antennas P - 7 4.1.2 Side-mounted Omnidirectional Antennas P - 7 4.1.3 Omnidirectional Gain Antennas P - 7 4.2 Directional Antennas P - 8 4.2.1 Gain Achieved via Horizontal Beaming P - 8 4.2.2 End-fire Array P - 8 4.2.3 Broadside Array P - 8 4.2.4 Antenna Systems P - 9 5. Particular Techniques used in GSM and DCS 1800 10 5.1 Diversity P - 10 5.1.1 Space Diversity P - 10 5.1.1.1 Omni-Base Station P - 11 5.1.1.2 Sectored Base Station P - 11 5.1.2 Polarization Diversity P - 11 5.1.2.1 Horizontal and Vertical Polarization P - 11 5.1.2.2 Polarization +45°/-45° P - 12 5.2 Indoor Antennas P - 12 – 1 –
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6. Car Antennas P - 13 6.1 λ/ 4 Antenna on the Car Roof P - 13 6.2 Gain Antennas P - 14 6.3 Rear Mount Antennas 6.4 Screen Surface Direct Mounting Antennas P - 15 6.5 Clip-on Antennas 6.6 Electrically Shortened Antennas 6.7 Train Antennas P - 16 7. Antennas for Portables 17 7.1 λ/ 4 Antennas P - 17 7.2 λ/ 2 Antennas (Gainflex) 7.3 Electrically Shortened Antennas P - 18 7.4 Field Strength Measurements Appendix with Diagrams B1 – B26 – 2 –
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Mobile Communications - Antenna Technology 1. Introduction In the last few years a large technological jump has taken place in the field of mobile communications due to the introduction of new mobile communication networks (GSM/PCN). The number of subscribers worldwide has risen to over 150 Million. Fig. 1 shows an overview of the mobile communications servi- ces and the relevant frequency ranges within Germany alone. The requirements on the antennas needed for the ever expanding networks are becoming continually higher: strictly defined radiation patterns for a most accurate network planning. growing concern for the level of intermodulation due to the radiation of many HF-carriers via one antenna. dual polarization electrical down-tilting of the vertical diagram. unobtrusive design. The following essay will give an insight into antenna theory in general, as well as the most important types of antennas and the special methods used for GSM/PCN systems. – 3 –
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2. Theory Antennas transform wire propagated waves into space propagated waves. They receive electroma- gnetic waves and pass them onto a receiver or they transmit electromagnetic waves which have been produced by a transmitter. As a matter of principle all the features of passive antennas can be applied for reception and transmission alike (reciprocality). From a connection point of view the antenna appears to be a dual gate, although in reality it is a quad gate. The connection which is not made to a RF-cable is connected to the environment, therefore one must always note, that the surroundings of the antenna have a strong influence on the antennas electrical features (Fig. 2).
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This note was uploaded on 08/08/2011 for the course CS 310 taught by Professor Aartisingh during the Spring '11 term at National Institute of Technology, Calicut.

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Basic Antenna - Basic Antenna Principles for Mobile...

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