Satellite Communications 6/10/5244 - 1
ITU Satellite Frequency Allocations 6/10/5244 - 2
Satellite Frequency Allocations S-Band, C-Band and X-Band Satellite Frequency Allocations in MHz ~ ~ ~ ~ ~ ~ ~ ~ Fixed REGION 1 mobile Aeronautical, Fixed Fixed mobile Radio-nav., REGION 2 mobile Fixed mobile Radar REGION 3 ~ ~ ~ ~ ~ ~ ~ ~ 2290 1675 1710 1980 2010 2025 2110 2120 2160 2170 2200 2300 2483.5 2500 2520 2535 2655 3400 3700 4200 4500 4800 5725 5850 6425 6725 7025 7250 7750 7900 8400 S-Band C-Band X-Band Ku-Band Satellite Frequency Allocations in MHz ~ ~ ~ ~ Aero- REGION 1 nautical Radar REGION 2 Radar REGION 3 ~ ~ ~ ~ 10700 10950 11200 11450 11700 12200 12500 12750 13250 13750 14500 14800 17300 17800 18100 Ka-Band Satellite Frequency Allocations in MHz ~ ~ REGION 1 REGION 2 REGION 3 ~ ~ 17700 19700 20100 21200 27000 27500 29500 30000 31000 Legend Space Operation/Earth Exploration/Space Space Research Down Extended FSS Down FSS Down FSS Allotment Plan Down Government FSS Down Research Down (Co-Primary) Space Operation/Earth Exploration/Space FSS Up Extended FSS Up FSS Allotment Plan Up Government FSS Up Space Research Up Research Up (Co-Primary) MSS/Radiodetermination Up BSS Plan Down Meteorological Down MSS/Government FSS Down (Co-Primary) MSS Down FSS/MSS Up (Co-Primary) (Co-Primary) Meteorological Down/ MSS/Government FSS Up (Co-Primary) BSS Plan Up MSS Up FSS/BSS Up (Co-Primary) MSS Up (Co-Primary) L-Band Satellite Frequency Allocations in MHz ~ ~ REGION 1 REGION 2 REGION 3 ~ ~ 1492 1525 1530 1533 1544 1545 1555 1559 1610 1626.5 1631.5 1634.5 1645.5 1646.5 1656.5 1660.5 Legend REGION REGION 2 1 Maritime/Land Mobile Down (Co-Primary) Emergency/Distress Down MSS Down MSS Up Maritime/Land Mobile Up (Co-Primary) Emergency/Distress Up Land Mobile Down Maritime Mobile Down Aeronautical Mobile Down Maritime Mobile Up Land Mobile Up Aeronautical Mobile Up REGION REGION 3 3 BSS = Broadcast Satellite Service FSS = Fixed Satellite Service MSS = Mobile Satellite Service 6/10/5244 - 3 ITU Regional Definitions
Frequency allocations C-Band － Transmit 5.925 - 6.425 GHz (U.S.) 5.625 – 6.425 GHz (I.T.U.) － Receive 3.700 - 4.200 GHz (U.S.) 3.400 – 4.200 GHz (I.T.U. ) Ku-Band － Transmit 14.00 - 14.50 GHz (U.S.) 13.75 – 14.50 GHz (I.T.U.) － Receive 11.70 – 12.20 GHz (U.S.) 11.20 – 11.70 GHz (ITU) Ka-Band － Transmit 27.5 – 30.0 GHz － Receive 17.7 – 20.0 GHz 6/10/5244 - 4
C-Band Advantages – Wide footprint coverage – Minor effects from rain – Lower cost for earth station antenna Disadvantages – Requires larger antennas – Requires larger RF power amplifier – Effected by terrestrial interference (TI) – Difficult to obtain transmit license • Frequency clearance 6/10/5244 - 5
Ku-Band Advantages – Smaller antennas – Smaller RF power amplifiers Disadvantages – Greater effect from rain – Smaller footprint (beam) coverage 6/10/5244 - 6
Ka-Band Advantages – Smaller antennas – Smaller RF power amplifier Disadvantages – Greater effect from rain – Smaller footprint (beam) coverage – High equipment cost 6/10/5244 - 7
Polarization 6/10/5244 - 8
Polarization Provides increased satellite capacity (Allows frequency reuse) The directional aspects of the electrical field of a radio signal Linear ( 90 o Out of Phase ) － Horizontal (H) － Vertical (V) － All Ku-Band satellites are Linear Circular (180 o Out of Phase) － Right Hand Circular (RHCP) － Left Hand Circular (LHCP) 6/10/5244 - 9
Linear Polarization Linear Polarization – The electrical field is wholly in one plane containing the direction of propagation Horizonta l – Field lies in a plane parallel to the earth’s surface. Vertical – Field lies in a plane perpendicular to the earth’s surface. 6/10/5244 - 10
Circular Polarization Circular Polarization – The electrical field radiates energy in both the horizontal and vertical planes and all planes in between Right Hand Circular Polarization (RHCP) – the electric field is rotating clockwise as seen by an observer towards whom the wave is moving Left Hand Circular Polarization (LHCP) – the electric field is rotating counterclockwise as seen by an observer towards whom the wave is moving 6/10/5244 - 11
Linear Polarization Advantage – Lower Cost Antenna System • Feed Assembly (OMT) – Better Cross-Pol Isolation Disadvantage – Polarization Adjustment Required – Polarization changes depending on Latitude and Longitude – Greater chance of problems due to cross-pol interference – Faraday rotation in the ionosphere 6/10/5244 - 12
Circular Polarization Advantage – No polarization adjustment required • Fixed by Ortho-Mode-Transducer (OMT) – Less chance of cross-Pol interference Disadvantage – Higher cost antenna systems • Feed Assembly (OMT) – Slightly lower cross-Pol isolation 6/10/5244 - 13
Cross Polarization Isolation 6/10/5244 - 14
Antenna Polarization Co-Polarization – Polarity of the desired signal Cross-Polarization – Polarity of the unwanted signal Co-polarized antenna pattern Relative Power X-polarized pattern Azimuth Angle 6/10/5244 - 15
Antenna Cross Polarization Both the Main Carrier (V) and the Cross-Pol Component (H) In addition to the Main are received by the satellite Carrier(V) a Cross-Pol Component (H) is also transmitted from the Uplink Antenna V H H V Both the Main Carrier (H) and the Cross-Pol Component (V) are transmitted from the satellite and received at the downlink Antenna. At the downlink station a second 50 Cross-Pol Component is introduced. 40 Receive Antenna Isolation. 30 dB 34 dB 30 The Cross-Pol component that 20 is at the same frequency as the main carrier is receive isolation 10 0 The Cross-Pol component that Receive Transmit is offset from the main carrier Isolatoin Isolatoin is the transmit antenna isolation 6/10/5244 - 16
Antenna Cross Polarization Satellite Vertical Polarization Horizontal Polarization Receiver Filter Amplifiers Filter 6175.000 MHz L0=2225.00125 3949.99875 Uplink (IMUX) (OMUX) Horizontal L0=2224.99975 Vertical Polarization Polarization Receiver Filter Amplifiers Filter Uplink X-pol Component 3950.00025 50 The satellite LO 40 30 dB frequencies are not at the 34 dB 30 exact same frequency 20 10 0 Transmit Receive Isolatoin Isolatoin 6/10/5244 - 17
Antenna Cross Polarization 6/10/5244 - 18
Antenna Cross Polarization Receive Component Transmit Component • Transmit Isolation ≈ 27.5 dB • Receive Isolation ≈ 35.0 dB 6/10/5244 - 19
IFL Uplink Link Budgets 6/10/5244 - 20
IFL Downlink Link Budget Basic Link Budget – Illustrative purposes only Mod output = -15 dBm C/N u = EIRP e + G/T s - Lpu + K -10log(BW) IFL -6.5 dB -21.5 dBm Earth Station EIRP = 48.5 dBW U/C gain = 10 dB -11.5 dBm Sat G/T = 8.2 dB/K HPA gain = 40 dB 28.5 dBm Uplink loss = 199.4 dB TX antenna gain 50 dBi 78.5 dBm Boltzman = 228.6 dB Uplink space loss = -199.4 dB -120.9 dBm Bandwidth = 1265000 Hz Sat RX ant gain = 41 dBi -79.9 dBm Uplink C/N = 24.88 dB Sat receiver gain = 60 dB -19.9 dBm Sat Losses = -5.9 dB -25.8 dBm C/N d = EIRP s + G/T e - Lp d - 10log( K ) - 10log(BW) Sat amplifier gain 40 dB 14.2 dBm Sat EIRP = 22.2 dBW Sat TX ant gain = 38 dBi 52.2 dBm Earth Station G/T = 20.9 dBK Downlink space loss= -195.8 dB -143.6 dBm Path Loss = 195.8 dB RX antenna gain = 47 dBi -96.6 dBm Carrier Bandwidth = 1265000 Hz LNA gain = 60 dB -36.6 dBm Boltzmans Constant = 228.6 IFL losses = -14 dB -50.6 dBm Downlink C/N = 14.9 dB D/C gain = 10 dB -40.6 dBm Demod Input = -40.6 dBm 6/10/5244 - 21
IFL Uplink Link Budget 50 dBi Gain 40 dB Gain -15 dB out 10 dB Gain Modem Up-Converter HPA Feed - 2dB -3 dB -1.5 dB EIRP = Modem out – IF cable loss + U/C gain – RF cable loss + HPA gain – W/G loss + Antenna gain EIRP = -15 dBm – 2 dB + 10 dB – 3 dB + 40 dB – 1.5dB + 50 dBi EIRP = 78.5 dBm EIRP = 48.5 dBW Gain/Loss Unit Modem Output = -15.00 dBm IF Cable Loss = -2.00 dB U/C Gain = 10.00 dB RF Cable Loss = -3.00 dB HPA Gain = 40.00 dB W/G Loss = -1.50 dB Antenna Gain = 50.00 dB EIRP = 78.50 dBm 48.50 dBW 6/10/5244 - 22
IFL Uplink Link Budget 50 dBi Gain 40 dB Gain 10 dB Gain -15 dBm 8 W A Y HPA Feed Modem Up-Converter -1.5 dB -1 dB -1 dB -3 dB C O M B I N E R EIRP = Modem out – combiner loss – IF cable loss + U/C gain – RF cable loss + HPA gain – W/G loss + Antenna gain EIRP = -15 dBm – 9 - 2 dB + 10 dB – 3 dB + 40 dB – 1.5dB + 50 dBi Gain/Loss Unit EIRP = 69.5 dBm Modem Output = -15.00 dBm EIRP = 39.5 dBW Combiner Loss = -9.00 dB IF Cable Loss = -2.00 dB U/C Gain = 10.00 dB RF Cable Loss = -3.00 dB HPA Gain = 40.00 dB W/G Loss = -1.50 dB Antenna Gain = 50.00 dB EIRP = 69.50 dBm 39.50 dBW 6/10/5244 - 23
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