我搜索了下。原版英文里并没有括号里的解释。。。
The AN/APG-68(V5) scans the horizon by physically moving the antenna. The beam that the antenna normally emits is not able to scan more than 4.9 in the vertical. The Bar Scan function effectively removes this situation by moving the radar up 2.2 at the end of each scan in the horizontal. The amount of extra ‘bars; in the scan are indicated by the bar scan control. With this set to 1, the radar will scan just the single 4.9 slice of airspace. Set to 2, the radar will scan 2 bars of airspace; set to four it will scan four bars.