Electrical Downtilt
Electrical Downtilt
(OP)
I was looking at omni antennas with electrical downtilt, and I was wondering how exactly the electrical downtilt is realized in the antenna? I'm also curious what are the limitations. It seems the range is typically 2-10 degree downtilt, is 10 deg a practical limit? Thanks.
Peter
Peter





RE: Electrical Downtilt
You can confirm this by comparing the total physical length of the antenna to the wavelength. Two half-wave dipoles in such an arrangement would be just a shade over (due to the gap) one lambda in total length. Four would be 2 lambda. 8 is pretty rare and 'non 2^n' co-linear combinations are even rarer.
Stand-by in case someone else knows of different examples.
RE: Electrical Downtilt
RE: Electrical Downtilt
The practical limit for this type antenna is probably greater than 10 degrees and would depend on your operating bandwidth.
For normal arrays, there is no scan limit for good antenna engineers with good software. If you just guess at the antenna design, antenna pattern blindspots (due to mutual coupling) can occur when you scan off broadside at angles beyond ?say 30 or 40 degrees. The further out you scan, the more likely you get ugly blind spots. It's hard to scan out to 60, 70 or 80 degrees over a wide frequency range without some real ugly antenna patterns. We recently designed and built a large printed circuit antenna array that scans from broadside to endfire.
kch