This is false. All antennas have side lobes.
For more than a decade, RF Elements falsely claimed that their antennas magically had “no side lobes.” They supported this self-serving, misleading marketing by hand-drawing radiation patterns on their datasheets and providing low-detail patterns for only one polarization and frequency point.
They also told WISPs that they could save time and money and didn’t need to implement other isolation techniques—such as physical isolation, GPS sync, or active filtering—when co-locating antennas, because their antennas supposedly had “no side lobes.”
This caused many WISPs to deploy densely co-located towers with radios that were insufficiently isolated, resulting in colocated radio interference, poor performance, and degraded service to their subscribers, ultimately hurting their businesses and damaging the entire industry’s reputation.
Here is one documented example of this issue where a trusting WISP in Italy colocates many MikroTik radios with RF Elements horn antennas, believing that he does not need GPS sync because the horn antennas won’t interfere with each other: https://www.youtube.com/watch?v=frPdl_GlB1M&t=23m20s
RF Elements lists this as a testimonial on their website. There are countless other examples.
As a consequence of not disclosing their sidelobes, WISPs can not determine the actual locations of side lobes and nulls, can not place co-located antennas in those nulls, and can not accurately map coverages or create effective plans for frequency reuse.
This misleading marketing also started a race to the bottom: competitors who honestly and accurately represent their side lobes lose sales to RF Elements.
On their ePMP 3000 Dual Horn MU-MIMO Antenna, Cambium Networks provides computer generated radiation patterns with 45 dB of detail at 3 frequency points, for both polarizations, honestly representing the antennas sidelobes. This honest representation undoubtably causes Cambium to lose sales because RF Elements had persuaded much of the WISP industry that side lobes are problematic.
Getting back to the original topic, I wrote an article about overlapping sector coverages and how it is best to offset the coverage patterns by half the beam width to improve average signal strength. You might find this helpful: