SBCA Antenna Systems 5

Question 1

What is the primary advantage of a phased array antenna over a traditional parabolic dish for satellite communications?

Accepted Answer

Electronic beam steering without mechanical moving parts

Answer

Phased arrays steer their beam by adjusting the phase of signals at individual antenna elements electronically, enabling rapid beam repositioning without mechanical actuators.

Question 2

During antenna system commissioning, a technician measures a receive signal level 3 dB lower than the link budget predicts. Which is the LEAST likely cause?

Accepted Answer

The satellite's EIRP being 3 dB higher than specified in the link budget

Answer

A satellite transmitting 3 dB more than specified would cause the received level to be higher than predicted, not lower — it is the least likely cause of a 3 dB deficit.

Question 3

What is 'antenna gain roll-off' in the context of wideband satellite systems?

Accepted Answer

The reduction in antenna gain observed at frequencies near the band edge compared to the center frequency

Answer

Gain roll-off describes how antenna gain decreases toward the edges of the operating bandwidth, which must be accounted for in wideband link budget calculations.

Question 4

Which grounding practice is most critical for protecting a satellite dish installation from lightning damage?

Accepted Answer

Installing a dedicated ground rod at the dish base and bonding all metallic components to a single-point ground

Answer

Proper grounding requires a dedicated earth ground at the antenna structure and bonding all metallic components (dish, mast, coax shield) to a single common ground point.

Question 5

An antenna's beamwidth is measured at 0.7° at 14.25 GHz. A neighboring satellite is located 2° away in orbital arc. What is the approximate isolation advantage provided by the antenna's directivity?

Accepted Answer

The interfering satellite falls outside the half-power beamwidth, providing significant sidelobe attenuation

Answer

Since the 2° separation is nearly 3× the 0.7° HPBW, the interfering satellite falls well into the sidelobe region where antenna gain is substantially reduced.

(SBCA) Satellite Broadcasting and Communications Association Certification Practice Test

(SBCA) Satellite Broadcasting and Communications Association Certification Practice Test

SBCA Antenna Systems 5