Antenna Basics and Installation Guidelines. Mattias Hellgren, Senior RF Engineer Johan Sjöberg, Senior Mechanical Engineer

Transcription

1 Antenna Basics and Installation Guidelines Mattias Hellgren, Senior RF Engineer Johan Sjöberg, Senior Mechanical Engineer

2 Content Behavior of radio waves Antenna parameters Guidelines Antenna design for sustainable installation

3 Radio Waves Wavelength is the distance a radio wave will travel during one cycle Important measure, dictates the optimum size of an antenna and determines how the RF wave interacts with it s environment Wave length( λ ) = c / f c speed of light) = m/s f (frequency)= 1/s 868MHz = λ 0.346meter 433MHz = λ 0.693meter

4 Radio Waves Antenna radiation travels through the air and spread with constant energy The spread reduces the signal strength in a certain point since a receiver antenna can only pick up a part of the signal The weakening of the signal, when it takes place in an open environment without barriers called; free field propagation / attenuation

5 Antenna Installation Guidelines Multipath Reflection Diffraction Scattering Absortion

6 Radio Waves A radio wave that hits a barrier will be affected depending on the type of barrier (size, surface, material) Porous materials absorbs the signal A flat surface reflects the signal A rough surface can both reflect and absorb The angle of reflection is the same as the initial angle

7 Radio Waves Radio waves loses energy, not only due to Path Loss but also due to absorption of obstacles such as walls, windows, trees, or any other material (solid, liquid, gas Absorption of the signal reduces the energy of the wave that turns into heat The absorption reduces the signal's amplitude (strength) but retains its original wavelength / frequency

8 Attenuation due to Absorption Brick/Concrete Wall Cinder Block Wall Wooden Wall Double Pane Coated Glass 2,4GHz: 5GHz: -6 to -18dB -10 to -30dB 2,4GHz: 5GHz: -3 to -5dB -4 to -9dB 2,4GHz: 5GHz: -3 to -4 db -6 to -7dB 2,4GHz: 5GHz: ~ -13dB ~ -20dB

9 Radio Waves Scattering occurs when an RF signal strikes an uneven surface causing the signal to be scattered instead of absorbed Scattering attenuates the received signal Affects shorter wavelengths more than longer ones Rocky terrain, Leafy trees, Chain link fencing, Rain, Smog

10 Radio Waves Multipath occurs when the signal reflects on surfaces Multipath propagation phenomenon that results in radio signals reaching the receiver antenna by two or more paths Multipath causes interference of the signal including constructive and destructive depending on the time of arrival (phase) Wave length dependent Hangars, distribution centers, walls, racks, shelves

11 Antenna Parameters VSWR Voltage Standing Wave Antenna VSWR Level of matching to 50Ω Transmitted wave High VSWR High Losses VSWR = 1:1 = >100% transmitted VSWR = 2:1 => 89% transmitted Reflected wave VSWR= U forward + U forward - U Reflected U Reflected Transmission line CABLE Forward wave

12 Antenna Parameters VSWR Voltage Standing Wave A RF transmitter = Water pump Cables/connector = Pipes and junctions B Water pumps water at a rate and force equal to pipe A Pipe B will cause a mismatch in impedance because it is a smaller pipe Results in a buildup of pressure in pipe A and within the pump. At this point, two things can happen: Water flowing out of the end of pipe B will be less than the original potential of the water pump or the pipe A and the water pump may be destroyed in some way. Leakage. Always use the same impedance on cables and connectors for installations

13 Installation of ¼-wave antenna close to metal Antenna tuning could be influenced depending on distance between antenna and metal Radiation pattern will be distorted/changed from omnidirectional to directive depending on distance to metal Reduced radiation opposite of installation surface Shadowing

14 Antenna pointing away from installation surface Antenna touching installtion surface Mismatch loss 0.41dB = transmitted/received power ~91% Mismatch loss 2,35dB = transmitted/received power 58%

15 Antenna Parameters - Radiation pattern Graphical representation of the power radiated by an antenna as a function of the direction away from the antenna Radiation pattern 2D Cuts are made in different axes depending on antenna type X;Y, X;Z 3D measurements results in a volume representing radiation in all directions ( all cuts are measured)

16 Antenna Parameters - Radiation pattern Gain of antenna ¼-wave antenna Ground plane Typical ¼-wave antenna radiation diagram

17 Antenna Parameters - Radiation pattern Directivity: Energy focus in a particular direction Gain in reference to a standard antenna Isotropic antenna or resonant half-wave dipole antenna 0dBd=2,15dBi Light bulb vs. spotlight: A spotlight will provide more light in a particular direction, and less light in other directions.

18 Antenna Installation Guidelines An antenna mounted ¼-wavelength from a metal surface will act as a mirror and reflect energy in the direction away from the metal surface There will be shading behind the metal 4 Try to achieve line of sight between receiver and transmitter

19 Antenna Installation Guidelines Multipath Reflection Diffraction Scattering Absortion

20 Antenna Installation Guidelines Mount the antenna in an open area without any nearby objects such as walls, ceiling, metal beams beacon lights Signal coverage will change due to the surrounding environment For permanent installation, consider in-use environment. e.g. Metal doors that are open during installation and then closed will have a dramatic impact on signal coverage

21 Antenna Installation Guidelines Use RF cables/connectors with the same impedance (50 Ohm) Do not expose RF-cables to pressure or sharp bends => reduced electrical performance Coaxial cable, minimum installation radius ~R=Diameter *5 Larger diameter of coaxial cable reduces losses Higher frequency -> Higher losses

22 Smarteq product design for a sustainable installation

23 Material that could handle rought environments and multi purpose installations Plastic resin used in: SmartDisc AllDisc LPCA

24 Material that could handle rought environments and multi purpose installations Thermoplastic Used in Gaskets and Sealings

25 Smarteq product designs for a sustainable installation Material selected to be able to handle rought environments and perform year after year Sealings with multiple sealings surfaces ensures a tight seal Well defined cable routings, solderings Designed for assembly with high repeatability enables stable performance and high quality

26 Competitor analysis The datasheet might specify the same RF performance but.

27 Smarteq antennas are designed for multipurpose installations Multi operator router Fleet management Inside coverage : 4 x SmartDisc or AllDisc : SmartDisc Combi or Alldisc Combi or SmartWing : SmartDisc Wifi dual band

28 LP80x family - a Multipurpose design

29 Principal AMR system overview

30 EV charging pole Mission: Reliable communication for EV charging pole system with the intention; Operational in rural areas Project: Mesurements of antenna in existing charging pole LS-3 Suggest alternative antenna for LS-3 product range Take part in development of new charging pole series LS-4 LS-4 Solution: Substantial improvement with Smarteq replacement antenna for LS-3 Consealed antenna solution for LS-4

31 Smarteq designs enables multi installation capabilities

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