Forum

Is there a reference that lists general ranges for each type of antenna. I missed question 11 in chapter 4 due to reading in the chapter that planars are good to about 1mile and yagis to 2miles. It was mentioned that there are high-gain yagis but didn't specify their typical range.

TIA

inherently impossible. range is a function of

tx power
antenna gain
rx signal threshold

too many variables to decree X antenna = Y gain

a 15 dB panel antenna should have the same range as a 15 dB yagi or dish in any given system

yagi gain is effectively limited to ~18 db. beyond that the boom sags, the antenna distorts, the gain falls off

RJT

Another area concerning antenna usage is that of beamwidth. The higher the antenna gain, the narrower the beamwidth. In an ideal world, this wouldn't be a problem. In reality, several problems occur. Firstly, lining up high gain parabolics ( for example ) is an iterative process at both ends. There is ( or should be ) a lot of "back and forth" at both ends during the peaking process. I have seen many ocassions where an antenna has been peaked on the first sidelobe at one end. The Tx power has been "jacked up" ( many times illegally ) to compensate.

When you are finally "tightening the bolts" which connect the antenna to the boom or post or whatever, great care has to be taken. If people are too "rough" with the adjustment, tiny ( but important ) shifts can occur in antenna positioning. Usually this is not too much of a problem with short range systems, but with a system at the edge of performance limits per the link budget, this can cause problems.

Twist and sway on the mounting structure are important factors as well. If a flimsy, tall post is used, wind ( and sometimes even vibration from heavy trucks passing by ) can cause movement of the post ( and thus the antenna ).

Water ingress can cause huge problems. Even water vapor after a heavy rainstorm can cause massive attenuation in connectors etc. Good waterproofing using a UV resistant type of tape is very important. Be careful with silicone, as poor quality types can cause problems. Air bubbles in the silicone and "creep" can be problematic too.

Dave

ok i just wanted generalizations. In the cisco curriculum i remember they had something and thought there would be here as well especially since they ask related questions

Please i have been trying to log in to access the practice tests for CWSP and it has not been going through
can anyone help me?

If you are logged in here, then you can access your practice tests. Same login. Click "My Account" on the main menu above, and then go to your practice tests.