Attachment Radar

This document pretains to SES-MFS-20050831-01198 for Modification w/ Foreign Satellite (earth station) on a Satellite Earth Station filing.

IBFS_SESMFS2005083101198_483988

19700 Janelia Farms Blvd Ashburn, VA 20147 703-726-5500 Interference Evaluation of Earth Station Transmitter at Kapolei, HI to RADAR at Fort Shafter, HI Purpose: The purpose of this document is to describe the calculations and analysis used to evaluate the potential interference levels from the LORAL 13-meter Earth Station operating in the 5850 – 5925 MHz Band at Kaploei, HI into a military RADAR operated at Fort Shafter, HI. System Parameters: The operating and physical parameters used in the calculations and analysis for the earth station are in Table 1 and for the RADAR in Table 2. Table 1 Operational Parameters of 13-meter Earth Station Frequency Range 5850 - 5925 MHz MAX Transmit Power !23.5 dBW/MHz Transponder Power !9.7 dBW/MHz MAX EIRP 79.8 dBW/MHz Antenna Gain 56.3 dB Antenna Size 13 meters Antenna Side Lobe Gain !32 – 25*Log(θ), ≥ -10 dB Antenna Center Line !49.5 feet Site Ground Elevation !157 feet Table 2 Operational Parameters of the Military RADAR Frequency Range 5400 - 5900 MHz Transmit Power 250 kW Peak Power 250 Watts Average Power Output Tube Magnetron Pulse Width Variable, !1.0, µseconds Pules Recurring Frequency (PRF) Variable, !1000 pulses per second Receiver sensitivity !-130 dBW/MHz Antenna Gain (main beam) !32 dB, 1584 (side lobe) - 10 dB, 0.1 Antenna Motion !360 Fixed Rotation Antenna Height !150 feet Ground Elevation of Site !78.7 feet Note: ! shows the parameters used in the creation of the profile and values in the calculation

Calculations: Two procedures were carried out for the determination of the interference condition created by the earth station operation. The first procedure was to look at the profile between the earth station antenna and the RADAR antenna. The terrain profile for the path is shown in Figure 1 of this memorandum. The profile shows that there is a line-of-sight condition between the two antennas. The next procedure calculated the interference level coupled from the earth station to the RADAR system. To determine the level the following formula was used. Pi = (Pm(t)*Ge*Gr*λ2)/((4Π)*R) 2 Pi = Power spectral density at the RADAR antenna terminals, Watts/MHz Pm= Power spectral density transmitted by the earth station, MAX 23.5 dBW/MHz Pmt= Power spectral density transmitted by earth station to single transponder, 9.7 dBW/MHz R = Distance between the earth station and RADAR antennas, 17.7 miles or 28,492.7 meters Ge = Gain of the earth station antenna in the direction of RADAR antenna, -10 dB or 0.1 Gr= Gain of the RADAR antenna in the direction of earth station antenna, main beam 32 dB or 1584.9, side lobe -10 dB or 0.1 λ = Wavelength of frequency at the center of the earth station band, 0.0508 meter Calculation Results: The calculation was performed for the RADAR main beam and side lobe antenna position toward the earth station antenna. The calculation was made for the earth station maximum transmit power and the transmit power to a single satellite trasnsponder. The results are shown in Table 3. Table 3 RADAR Main Beam and Side Lobe Interference Levels from Earth Station RADAR Antenna Position Interference Level Margin vs RADAR SENS dBWatts/MHz dB Main Beam-to-earth station -91.4 -38.6 Max Tx Power Main Beam-to-earth station -105.2 -24.6 Single Transp Side Lobe-to-earth station -133.4 +3.4 Max Tx Power Side Lobe-to-earth station -147.2 +17.2 Single Transp From the calculated results it can be seen that there will be interference to the RADAR when the main beam is directed toward the earth station antenna. There will be no interference when the RADAR main beam is pointed away from the earth station. Conclusions: For the present position of the earth station and RADAR there will be interference to the RADAR every time its antenna sweeps past the area where the earth station is located. The profile indicates line-of-sight conditions for the two antennas. The calculations show that anywhere there can be RADAR antenna main beam coupling toward the earth station antenna interference will occur.

260 240 220 200 180 160 140 Elevation (ft) 120 100 80 60 40 20 0 -20 0 2 4 6 8 10 12 14 16 Path length (17.74 mi) Site 1 Frequency (MHz) = 5900.0 Site 2 Latitude 21 20 12.60 N K = 1.33 Latitude 21 18 00.00 N Longitude 158 05 21.10 W %F1 = 100.00 Longitude 157 49 00.00 W Azimuth 98.16° Azimuth 278.26° Elevation 157 ft ASL Elevation 79 ft ASL Antenna CL 49.5 ft AGL Antenna CL 150.0 ft AGL Figure 1 Path Profile Kapolei - RADAR Apr 28 05

Figure 2 Map Over-Lay of Interference Path


Document Created: 2006-02-22 11:52:50
Document Modified: 2006-02-22 11:52:50
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