Directional Antenna Information

0253-EX-CN-2016 Text Documents

ViaSat, Inc.

2016-11-22ELS_184777

Exhibit A Fixed Antenna Specifications 1 Parabolic Antenna Beamwidth This application for an experimental license includes the use of a 1.22 meter (4 ft) parabolic antenna transmitting a CW signal at frequencies between 1668.4 and 18000 MHz. Antenna beamwidth is a function of wavelength or more practically the transmit frequency. Below is the formula used to determine the peak gain as a function of efficiency (η), diameter (D) and wavelength (λ): "  2 # πD Gpeak = 10log η (1) λ The peak gain of a parabolic antenna can also be calculated as a function of efficiency (η) and the half power beamwidth(θ3dB ): "  2 # 70π Gpeak = 10log η (2) θ3dB Equating 1 and 2: "  2 # "  2 # πD 70π 10log η = 10log η (3) λ θ3dB  2  2 πD 70π η =η λ θ3dB  2  2 D 70 = λ θ  3dB 70c θ3dB = Df   20985472060 θ3dB = (4) Df Figure 1 shows the relationship between frequency and beamwidth for a 4 ft (1.22 meter) parabolic antenna. Table 1 shows the beamwidth for the specific frequencies in the request for an experimental license. 1

Figure 1: Beamwidth as a function of frequency [MHz] Frequency [MHz] Beamwidth [◦ ] 1747 9.88 2200 7.82 2250 7.64 3649 4.71 4200 4.10 8900 1.93 12700 1.35 18000 0.96 Table 1: Relationship between frequency and beamwidth. 2 Orientation of Beam The transmit antenna located at 33◦ 570 48” N by 84◦ 60 51” W is orientated in the horizontal plane 91.50◦ from true North and in the vertical plane −1.7◦ from the horizontal plane. Figure 2 shows the elevation profile of the path between the transmit and receive antennas. 2

Figure 2: Beamwidth as a function of frequency [MHz] Calculation of the vertical orientation of the beam is shown below: 1084f t − 927f t tan(θ) = (5) 5280f t 157 = 5280   157 θ3dB = arctan 5280 ◦ = 1.7 (6) 3


Document Created: 2016-11-22 18:29:56
Document Modified: 2016-11-22 18:29:56
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