Comparison of Mechanical vs. Electrical Beamtilt |
Figure 1. No Beamtilt |
Figure 1 shows the cross-section of a broadcast pattern with no beam tilt applied. For comparison purposes, the peak gain is assumed to be 1. The pattern extends in a "donut" shape parallel to the horizon. |
Figure 2 shows the same antenna with Φ° beam downtilt applied. The peak gain remains at 1; but the same cross-sectional "donut" pattern is now tilted Φ°, with one edge tilted down, the opposite edge tilted up. |
Figure 2. Mechanical Beamtilt, Angle Φ° |
Figure 3. Electrical Beamtilt, Angle Θ° |
Figure 3 shows the same antenna with Θ° electrical downtilt applied. The peak gain has dropped to less than 1, but the cross-sectional pattern is now curved down in all directions, changing the "donut" shape to a cup or cone shape. Angle Θ and peak gain depend on the design parameters. |
Figure 4 shows the same antenna once again, this time with both Φ° of mechanical downtilt and Θ° of electrical downtilt. The cross-sectional cupped shape of figure 3 is now tilted as in figure 2. |
Figure 4. Mechanical Downtilt, Angle Φ°, Combined with Electrical Downtilt, Angle Θ° |
Last updated: 11/01/2006
Webmaster: Al Friend
© copyright 2006 Howell Laboratories, Inc.
|
We'll be in Amsterdam at IBC 2010, September 10-14.