Radio hopTerminal stationRepeater stationTerminal stationBBMTRDMTBBRDRadio hopBB Baseband signalM ModulatorDemodulatorT TransmitterR ReceiverFig. 1 Principles of a Radio Relay Link (TT2540EU02AL_01 Basics of Radio Relay, 5)

Fig. 2 Structure of a Radio Relay Connection (TT2540EU02AL_01 Basics of Radio Relay, 9)

Radio beamOptical horizonRadiohorizonLine of sightActual radius of the earthApparentradiusof the earthActualradiusof the earthFig. 3 Radio path in the atmosphere (TT2540EU02AL_01 Basics of Radio Relay, 13)

Direct beamFresnel ellipsoidAntenna 2TerrainprofileSea levelAn-tenna 1d1d2rF1(d1,2)Fig. 4 Radio hop with clear fresnel zone (TT2540EU02AL_01 Basics of Radio Relay, 17)

Fig. 5 Fading on microwave links (TT2540EU02AL_01 Basics of Radio Relay, 21)

DRS 140/6700(CCIR-Recommen-dation 384-4)DRS 34/13000orDRS 140/13000(CCIR-Recommen-dation 497-2)DRS 140/18700(CCIR-Recommen-dation 595-1)DRS 34/18700(CCIR-Recommen-dation 595-1)Fig. 6 RF-Channel Arrangement for digital radio relay systems (TT2540EU02AL_01 Basics of Radio Relay, 25)

Fig. 7 Routing of a radio relay link (TT2540EU02AL_01 Basics of Radio Relay, 29)

EXERCISES