Coaxial Antenna. Properties and use. Reijo Kekäläinen ROK/

Transcription

1 Coaxial Antenna Properties and use Reijo Kekäläinen ROK/

2 Need for Indoor Coverage Wireless communications are increasing rapidly Growth in the use of mobile services and products Growing use of mobile communication increases the demand for sufficient radio coverage in many places UMTS frequencies make signal propagation worse because of bigger open air attenuation and even worse building structure penetration ROK/

3 Need for Indoor Coverage Propagation of electromagnetic waves are disabled into constructions of heavy and conducting material Portable receiver moving in the building experiences fading In the future mobility of work makes demands for wireless office Growing need for security systems for buildings ROK/

4 Communication in underground areas and halls, such as car parks Communication in metro systems and railway tunnels Communication in mine tunnels Communication in road tunnels Communication systems in buildings such as offices, hospitals, shopping centers, airports Applications ROK/

5 Applications Police, fire and rescue services in all areas mentioned Wireless LAN (WLAN) Area access detection and security AM or FM-radio detection in radio shadowed places Cordless telephone systems Communication in ships ROK/

6 Basic construction of a coaxial antenna (radiating cable) Basic construction elements inner conductor solid copper wire copper plated aluminium wire copper tube in cables of large dimensions concentric dielectric contains inner skin, low loss foam (PE) and outer skin dielectric has good bonding to the inner conductor by the inner skin more than 80 % of foaming degrees can be achieved by a modern extruding and gas injection process outer skin is an effective barrier against moisture ROK/

7 Basic construction of a coaxial outer conductor antenna welded, corrugated and slotted copper tube or longitudinal overlapped copper tape with periodic slots determines the radiating properties mica barrier tape option improves the fire safety of the cable sheath black HD polyethylene grey or black halogen free fire retardant thermoplastic also other colors available ROK/

8 Coaxial antenna theory coaxial antenna has basic coaxial cable transmission characteristics with some exceptions: the TEM wave that propagates inside the cable also radiates outwards from the cable the coupling mechanism between the cable interior and the external environment can be created by small apertures in the cable outer conductor ROK/

9 Coaxial antenna theory The cable acts as continuous antenna and transmission line at the same time the electromagnetic coupling mechanism and radiation characteristics are determined by the configuration of the apertures: key factors are the size, shape, position and spacing of the apertures based on the coupling and radiation mechanism cables can be divided for coupled mode cables and radiating mode cables ROK/

10 Coaxial antenna theory Coupling mode cables In the coupled mode cable the spacing of the apertures are smaller than the operating wavelength coupling mode cables work on the wide frequency range coaxial antennas with a corrugated and milled outer conductor are typical examples ROK/

11 Coaxial antenna theory Radiating mode cables In the radiating mode cables the apertures are typically periodically configured with a spacing comparable to the operational frequency with a proper configuration the cable radiates within the required frequency coaxial antennas with a slotted overlapped copper tape as outer conductor are typical examples ROK/

12 Electrical characteristics The most common characteristic impedance is 50 Ω (typical for radio communication) In coaxial antennae the coupling mechanism has an effect on the total attenuation of the cable: α = α f + 1 f + α 2 + α3 α 4 where α = attenuation at a given frequency (db/100m) α 1 = loss coefficient of conductors α 2 = loss coefficient of dielectric α 3 = loss coefficient of coupling α 4 = losses in the near magnetic field because of the wrong assembly of coaxial antenna (e.g. too near the walls) f = frequency ROK/

13 Electrical characteristics The attenuation of the coaxial antenna is measured according to the standard IEC ground level method cable is laid on non-metallic spacers cm from concrete floor free space method (more common method) cable is laid on wooden posts at height of m when using this method the attenuation is calculated using the following formula: α = N e N L s o [ ( T 20) ] ( db /100m at 20 C) 100 ROK/

14 Electrical characteristics where α = attenuation (db/100m at 20ºC) N e = power level at the beginning of the cable (dbm) N s = power level at the end of the cable (dbm) L = length of the cable (m) T = temperature of the cable (ºC) Coupling loss is measured according the same standard as above Coupling loss is the ratio of the received power at the antenna (2 m from cable) to the power in the cable depends on the coupling and radiating mechanism of the cable ROK/

15 Electrical characteristics is calculated (when using free space method) by using formula α = N N α P (db where c e ( ) ) α c = coupling loss (db) N e = power level at the beginning of the cable (dbm) N r = power level at antenna (dbm) P= distance from antenna to the feeding point (m) is characterized by two typical values: mean value α c50 : 50 % of the measured local values are smaller than this value mean value α c95 : 95 % of the measured local values are smaller than this value is typically db r ROK/

16 Cable types and main features NK Cables offers several cable types according to the cable diameter and coupling/radiating mechanism: RFX or RF2X 1/2-50 RFX or RF2X 7/8-50 RFX or RF2X 1 1/4-50 RFX or RF2X 1 5/8-50 RFXT 5/8-50 RFXT 7/8-50 RFXK (several dimensions) ROK/

17 Cable types and main features RFX has a welded corrugated outer conductor (coupling mode cable) Also RFX with extra fire protection (Mica tape) is available RFXT has an overlapped copper tape outer conductor (radiating mode cable) ROK/

18 Cable types and main features Coaxial antennae have the following main features: low attenuation and optimized coupling loss high mechanical strength and stability polyethylene skin over dielectric as a moisture barrier fire retardant, low smoke and halogen free sheath available easy installation characteristics colored cables if required ROK/

19 Cable types and main features RADIATING COAXIAL CABLE Jacketing options Materials high density PE low density PE halogen free, low smoke, fire retardant colored cables Fire performance IEC /2 (halogen, corrosive) IEC /2 (low smoke) IEC (flame retardant) IEC C (fire retardant) Jacketing options are in the cable specifications ROK/ TYPE RFX 7/8"-50 RFX 7/8"-50 GHF RFX 7/8"-50 BHF CONSTRUCTION Inner conductor Copper tube Ø 9.0 mm Dielectric Three layer polyethylene insulation Ø 22.2 mm solid/foam/solid Outer conductor Corrugated and slotted copper tube Ø 24.9 mm Sheath See table below Ø 27.5 mm Marking ΩHMAX, manufacturer's name, cable type, manufacture week, year and metre mark ELECTRICAL CHARACTERISTICS at +20 C MECHANICAL CHARACTERISTICS Operating temperature range JACKETING OPTIONS Characteristic impedance 50 ± 2 Ω Velocity factor 0.88 Capacitance 76 pf/m Attenuation measured according to IEC free space method. at 150 MHz 1.9 db/100m at 450 " 3.3 " at 900 " 4.9 " at 1.8 GHz 7.3 " at 2.2 " 8.2 " Coupling loss measured according to IEC free space method, antenna perpendicular to the radiating cable. 1.8 GHz values measured with horn antenna. 50% value 95% value at 150 MHz 67 db 77 db at 450 " 70 " 80 " at 900 " 73 " 82 " at 1.8 GHz 77 " 88 " at 2.2 " 75 " 87 " Weight Maximum pulling force Minimum single bending radius TYPE Jacket IEC /-2 halogen free, not corrosive C IEC low smoke emission IEC fire retardant 550 kg/km 1800 N 250 mm UV retardancy Min. installation temperature RFX 7/8"-50 Black HD polyethylene yes no no yes -20 C RFX 7/8"-50 GHF Grey,halogen free fire retardant thermoplastic yes yes yes no -5 C RFX 7/8"-50 BHF Black,halogen free fire retardant thermoplastic yes yes yes yes -5 C

20 Indoor system design Here an interior-building project is dealt with Same principles also applied to other applications Information to be required for the initial values building construction utilization of building equipment location; transmission possibilities etc. floor area; shape number of floors; height, underground parts materials; floors, walls, construction, windows, etc. (typical loss factors for each material) typical size of rooms; offices, halls, etc. risers; elevators, cable ducts etc.; location ROK/

21 Indoor system design existing radio environment outdoor BTS near the building capacity; cells, number of TRX s signal strength; cells, distances, direction used frequencies indoor system; signal strengths, levels of interference radio environment needs indoor micro BTS (pico-cell) or utilization of outdoor sites capacity; different needs in different parts of the building coverage; different needs in different parts of the building ROK/

22 limitations Indoor system design frequency planning; nearby cells, disturbances signal power: EMC requirements, devices and biological harmful radiation (not possible with coaxial antenna) equipment location costs operator needs ROK/

23 Indoor system design Indoor planning preliminary survey measurement plan including routes, floor layouts, permission carry out measurements analysis (categorization) measuring the signals from macro layer (from BTS s outside building) measurement results are analyzed to see if there is enough coverage and capacity inside the building if not indoor solution is required measurements of the signals from test transmission is carried out ROK/

24 Indoor system design pico-cell planning simulations of the new indoor system (antennae locations) there are many tools to do the radio network simulations e.g. NPS/i (Nokia tool), SitePlanner, WISE, in simple systems the calculations can be made by hand (a power budget calculation) the indoor system proposal is introduced to the operator coverage plot measurement results indoor solution proposal ROK/

25 Indoor solution in NK Cables head office in Espoo Finland implemented in co-operation with Sonera more uniform coverage achieved compared to the old system (distributed antennae) Indoor system design ROK/

26 Indoor system design INDOOR COVERAGE OF NK CABLES' HEAD OFFICE MEASURED MARGIN OF SIGNAL LEVEL (db), COMPARISON LEVEL -80 dbm old distributed antennae network new coaxial antenna network 1800 network MEASUREMENT LOCATION NUMBER ROK/

27 Indoor system design Cost comparison of networks of NK Cables Head Office Old distributed antennae network Cables feeder 8700 connectors 2350 power splitters 8000 antennae labor costs Total costs FIM = EUR New coaxial antenna network Cables feeder 2020 antenna connectors 2100 power splitters 5600 cable hangers 4530 jumpers 510 terminators 3220 labor costs Total costs FIM = EUR ROK/

28 Indoor system design Planning procedure INDOOR PLANNING PRELIMIN. SURVEY Measurement plan: - Routes - Floor layouts - Permissions Signals from macro layer Signals from test transm. CATEGORISATION MEASUREMENT RESULTS YES ENOUGH COVERAGE ENOUGH CAPACITY YES PICO CELL PLANNING PICO CELL MEASURE- MENTS Simulations based on NPS/i Criteria for Indoor Coverage and Capacity COVERAGE PLOT MEASUREMENTS INDOOR SOLUTION PROPOSAL ROK/

29 Power budget calculation It is the main part of the pico-cell planning Factors for power budget calculation: base station transmitter output level and receiver sensitivity jumper cable loss feeder cable loss power divider loss coaxial antenna longitudinal loss repeater gain (gain of the bi-directional amplifier) if amplifiers needed in system ROK/

30 Power budget calculation filter losses if filters needed in system coupling loss from coaxial antenna cable safety margin (5-20 db depending on the installation and the environment) contains fading margin and possible extra margin mobile station antenna loss or gain mobile station receiver sensitivity and transmitter output level with simple addition of these factors the probable signal strength in the radio network can be calculated ROK/

31 Power budget calculation example at 900 MHz Output power of Mobile Station (1 W) and antenna gain (0 dbi) 30 dbm Coupling loss e.g. 82 db/2 m (here 6 m and 95%) 87 db Coupling loss variation (fading) 10 db Coaxial antenna attenuation e.g. 49 db/km (100m) 5 db Power divider loss e.g. 3.5 db (2 pieces) 7 db Jumper cable (1 piece) 1 db Feeder loss e.g. 39 db/km (50m) 2 db Total 30 dbm 112 db Output power minus losses -82 dbm Receiver sensitivity of base station -112 dbm Safety margin 20 db ROK/

32 Implementation of the system The system s equipment is installed into the building structure requirements for coaxial antenna installation: at least 100 mm away from walls or ceiling to maintain good electrical characteristics coaxial antenna is often installed above the false ceiling in buildings special non-metallic clamps should be used recommended clamp distance for large diameter cables (1 1/4 and 1 5/8 ) is 1500 mm and for smaller cables 1000 mm ROK/

33 Implementation of the system recommended clamp distance for cables with suspension wire is 2500 mm bends of the cable should be limited to the minimum bending radius according to cable specification fire retardant, halogen free cables have to be installed carefully, because they are more sensitive to abrasion in a tunnel the best location is usually at the top in the middle when installing coaxial antenna, metallic parts of the building structure should be avoided cable must be kept clean from metallic dirt and dust (e.g. in mines) ROK/

34 Implementation of the system Other equipment needed connectors RFX (corrugated) cables can use same connectors as normal feeder cables for RFXT cables special connectors are needed power splitters and directional couplers depends on the structure of the project (e.g. 2:1, 10:1, etc.) 50 ohm termination with adequate power handling capability is usually put onto end of antenna line amplifiers, filters, antennae if needed ROK/

35 System verification Field measurements stand-alone mobiles radio network measurement software e.g NMS/X Measurement results are studied and compared to the designed parameters Parameter tuning based on network statistics and field measurement data to gain best possible quality and performance out of existing installation The effect of the new setting is monitored again ROK/

36 System verification Verification finally the building is verified by using available radio network software a predefined verification procedure is usually used the verification report to the operator is checked against the planning criteria final acceptance is achieved ROK/

37 System verification Optimisation and verification tasks OPTIMISATION Field Measurements NMS Statistics PLANNING AFTER IMPLEMENTATION Paramter Tuning VERIFICATION Field Measurements NMS Statistics Measurements Verification Raport ROK/

38 Benefits of using coaxial antenna in indoor systems Easy to use and design Usually an inexpensive solution compared to the other structures gives uniform response along the antenna line fewer blocking characteristics doesn t disturb other systems in the building gives off no harmful radiation to people nearby plugs in the tunnel structures don t affect the response ROK/

39 Benefits of using coaxial antenna in indoor systems coaxial antenna easily supports equipment on a different radio frequency (broadband capability) with one coaxial antenna many different kinds of radio systems could be served additional services can be added later without extra installation costs it is easy to increase capacity ROK/

40 Future prospects We ll offer whole package cables, connectors, jumpers, splitters, power dividers, filters, amplifiers, design work we ll have more products e.g. RFFX 1/2, RFEX 7/8 and RFXT 1 1/4 lot of type testing in near future we ll have proper brochures about coaxial antenna products future expectations are very promising in general ROK/

41 Year Country Customer Cable type Quantity km 1989 FINLAND Mobira, Siemens RFX 1/2 1 NEW ZEALAND New Zealand Railways RFX 7/ FINLAND Telecom Finland RFX 1/2 2 Telecom Finland RFX 7/ FINLAND Telecom Finland RFX 1/2 2 SPAIN Barcelona Metro RFX 7/ FINLAND Helsinki City Energy RFX 1/2 2 Telecom Finland RFX 1/2 3 NEW ZEALAND Intelcom Services RFX 7/ HOLLAND NKF RFX 1/2 4 NKF RFX 7/ FINLAND Helsinki City Energy RFX 1/2 21 Nokia Telecommunications RFX 1/2 1 Telecom Finland RFX 1/2 3 RFX 7/8 6 HOLLAND NKF RFX 1/2 HF 1 NEW ZEALAND Intelcom Services RFX 1/2 3 ROK/

42 Year Country Customer Cable type Quantity km 1995 FINLAND Finnish State Railways RFX 7/8 3 Helsinki City Energy RFX 7/8 HF 2 Helsinki Telephone Company RFX 7/8 1 Onninen RFX 1/2 2 Tekmanni RFX 7/8 3 Telecom Finland RFX 7/8 10 RFXK 1/2 5 RFXK 7/8 5 PORTUGAL Lissabon Metro RFX 7/8 HF 13 SOUTH KOREA Arkay International RFX 1/2 HF 25 SWEDEN ABB Norsk Kabel RFX 7/8 HF 1 ABB Norsk Kabel RFX 7/ FINLAND Helsinki Metro RFXT 7/8MBHF 11 Radiolinja RFX 7/8 2 Finnet Logistics RFX 7/8 3 RFXK 7/8 2 Onninen RFX 7/8 1 Telecom Finland RFXT 7/8 MBHF 11 HONG KONG Chung Wang Electrical Co. RFX 7/8 5 RF2X 1 1/4 HF 1 POLAND PTH Meopta Sp.Z. RFX 1/2 HF 1 SOUTH AFRICA O.D.F. Technologies RFX 1/2 1 RFX 7/8 1 ROK/

43 Year Country Customer Cable type Quantit km 1996 RUSSIA IVO RFXK 1/2 1 SOUTH KOREA Arkay International RFX 1/2 HF 26 SPAIN NKF Iberica RFXK 7/8 HF 5 SWEDEN ABB RFX 7/ ENGLAND NTC for LUL RFTX 5/8 10 RFTX 7/8 30 RFXT 5/8 HD 25 RFXT 7/8 HD 35 SPAIN NKF Iberica RFXK 7/8 HF 20 RFX 900T 7/8 15 SOUTH KOREA Arkay International RF2X 1/2 HF 20 RF2X 7/8 HF THE NETHERLANDS Amsterdam Airport RFX 7/8 HF 15 REPUBLIC OF CHINA Taipei Metro RFX 7/8 ROK/ BFR MEXICO Metro RFXK 7/8

44 Year Country Customer Cable type Quantit km 2000 AUSTRIA Tomek for Metro RF2X 7/8 HF 2 FINLAND Orbis RFXK 1 1/4-50 BHF 5 NORWAY Bredengen RFX 1/2-50 BHF 2 NORWAY Bredengen RFX 7/8-50 BHF 2 RUSSIA RC&C RFXT 7/8-50 MBHF 3 SPAIN Comel for Metro Barcelona RFXK 7/8-50 BHF 3 SPAIN Comel for Ferrocarriles Catal. RFXK 7/8-50 BHF RUSSIA Information Industry Co. RFXT 7/8-50 MBHF 3 RUSSIA RC&C RFXT 7/8-50 MBHF 3 SPAIN Comel for Ferrocarriles P. Vasco RFXK 7/8-50 GHF 6 SPAIN RFX 7/8-50 BHF 2 ROK/