Tom DeReggi

"Adding a top shield or visor to Symmetrical horns will be more harmful than beneficial" - very likely. " changing the whole radiation pattern of antenna and thus " - well, that was sorta the idea, to purposely change the radiating pattern :-) Sounds like I'll need to experiment some to determine the best downtilt for our application. I will definitely post picts of the completed install, as we progress..

The Horn antennas are extremely compact, and from a physical perspective, they will fit very close togeather. Pretty much just limited by the radio height, and enough room to remove them from the twistport. However, has anyone done the math to determine how close we can collocated a groups of horns togeather and still have adequate isolation between the radios. For example, if we were to use the newest rev Ubiquiti Prism (w/ tx/rc filtering) and literally stack them as close togeather as possible, how much channel separation would we need? (im referring to AP to AP interference. I recognize CPEs would hear both APs near the edges) For example lets say we want to get 4 - 30deg sectors for 120 deg coverage on one vertical mast. Just wondering how much optimizing the physical separation on the pole will help. Im probably gonna stagger them alternating left and right of pole, and maybe going top down, stagger them 30, 90, 60, 120 (or similar) to aid in isolation, to optimize horizontal separation and to prevent sector's beams from crossing the other's path. But undecided on whether I need to add additional vertical separation or not. I'll likely use multiple bands, to have large amount of channel separation. But there can also be other RF factors, that are less obvious. Such as receiver overloading, or one magnetic field interacting with another magnetic field that is to close. .

rfelabs, What would be the viability to make/add optional top shields / visors for the 30deg horn antennas to reduce top side wasted energy? Currently the horns deliver a uniform round equal in all directions of its 30 deg beamwidth. 15 degs to the right, left, up, down, etc. Although that design could be ideal for many applications where the customers are at higher and lower elevation, its not ideal for traditional application where the AP PTMP antenna is mounted high on a tower above the elevations of most of its its subscribers. In a horn's case, the 15 degs going upward becomes just wasted lost energy. But worse, it complicates down tilting. In congested areas, Downtilt is essential to create coverage zones, to reduce coverage distance, to avoid interfering with neighboring towers. We observed, our past 5.x deployments to interfere with our other towers even 20 miles away, without using downtilt. Although Horns can be downtilted 15+ degrees to enable reducing coverage, that will also spread out to much energy downward to near field obstructions (especially in more urban areas with tall buildings) that could potentially reflect back to the tower at higher harmful signal strengths to cancel out the transmission signal due to out of phase or multipath signals. But worse, excessive downtilt, drops the signal 6db to the frontal core desired coverage area, because its being served by the top edge of the beamwidth. Without downtilt, the 15 degree offered in the downward direction is already plenty enough to accommodate any nearfield coverage. The above is one reason, rectangular sectors antenna with minimal vertical beamwidth (4 - 12 degrees) or electronic downtilt are often used. With that said, there are many other exciting benefits to the symmetrical Horn antennas, that make them favorable to utilize. For one, the small size foot print. And second the excellent front to back ratio and side lobe isolation. In my case, Im using the horns at one tower with very limited space, because we were forced to switch our colocation agreement to a price per square foot of antenna front panel surface area. Three 30deg horns have less than 1 sqft of frontal surface area, saving me a ton of money on colocation, at 4x to 6x saving over other traditional sector designs. (Yes, Im very pleased with Rfelabs!) So back to the original question.... a top shield or visor !? Sorta like a anti-glare or rain shield used on traffic lights. Having a shield, curved to attach to the Top 90deg-120deg rim, and extending straight out horizonatlly 6-12" (not at the slope of the horn). This could potentially block the upward beam radiation and reflect it downward to increase the TX gain at the core frontal focal point of the antenna, with less physical downtilt. In many cases, the symmetrical horn pattern is only needed in the lower 180 degrees Or would the shield, cause harmful reflections to degrade the signal more than the benefit of such? Is that something rfelabs has already experimented with? Tom