6 dB == half the range for an antenna if you are presuming a certain fade margin. .
Path loss = 96.6 + 20 log F + 20 log D F is frequency in GHz, D is distance in Miles. If you say 1 GHz (for simplification) and 1 Mile path loss is 96.6 dB: At two miles it is 102.62 dB. At 3 dB down the range has decreased by 70% I think a beamwidth showing 70% to 100% range is more useful and honest than 50% to 100%. In other words, 3 dB down in receiver voltage is within the normal daily fluctuations. Not going to make or break a connection. 6 dB down is significant and could cause trouble. From: Mathew Howard Sent: Wednesday, April 11, 2018 9:29 AM To: af Subject: Re: [AFMUG] Rfelements I'm not sure if the RF Elements horns are rated at 3db or 6db, but I know RF Elements list the beamwidth at both points for their normal sectors (which is the best way to do it, if you ask me). It seems to be a lot more common these days to use the 6db beamwidth for marketing purposes, but I think there are actually some valid reasons for doing that - if the manufacturer is recommended that you use antennas that are 90 degrees at -6db, rather than -3db for an ABAB deployment, for example (which is the case, with some of them, if I remember correctly), then it makes sense to sell those as a 90 degree antenna, so that the people that don't bother to check things like that don't buy the wrong antenna. On Wed, Apr 11, 2018 at 10:21 AM, <ch...@wbmfg.com> wrote: Speaking generally here, not about this product specifically: A 30 is a 30 at some dB down from peak. Most reputable antenna manufacturers cite the beamwidth at the 3 dB down points on each side of the main lobe. That is called HPBW or half power beam width. Some go out farther to the 6 dB point to make their beam width seem wider than their competitors. Personally I believe that is false advertising. But I am sure they do not share my opinion. Look at the type of beamwidth. Should state how many dB down somewhere on the spec sheet. Other than that, horn antennas are very well characterized. They are used as lab standard calibration antennas. Other than the point where they choose to specify the beamwidth I think you can totally trust the specs. From: Steve Jones Sent: Wednesday, April 11, 2018 9:01 AM To: firstname.lastname@example.org Subject: Re: [AFMUG] Rfelements so if im getting the right feel, here, I CAN trust these spec sheets? a 30 is actually 30 and not 90? FB is real? Ive had two in play on EPMP1000 for some time but i keep pulling them and moving them elsewhere because of changes, so Ive never had one up long enough to see. I have use case for narrower patterns and more APs at some sites because the uplinks are getting more interference than id prefer, my only other option is to add the secondary antenna on the 2000, im not a fan of adding windload with no net capacity gain On Wed, Apr 11, 2018 at 9:57 AM, Steve Jones <thatoneguyst...@gmail.com> wrote: we have a substantial garbage dump On Wed, Apr 11, 2018 at 9:08 AM, Jaime Solorza <losguyswirel...@gmail.com> wrote: There's mountains near Steve's WISP footprint? Jaime Solorza On Wed, Apr 11, 2018, 7:45 AM Mike Hammett <af...@ics-il.net> wrote: You have that the other way around. A horn would be ideal in a mountain area. ----- Mike Hammett Intelligent Computing Solutions Midwest Internet Exchange The Brothers WISP ------------------------------------------------------------------------ From: "Sean Heskett" <af...@zirkel.us> To: email@example.com Sent: Tuesday, April 10, 2018 10:49:19 PM Subject: Re: [AFMUG] Rfelements I Totally agree with josh. They have a specific purpose so if you can deploy within those parameters they are great. Unfortunately our area isn’t conducive to that type of deployment because of terrain. In the mountains you need antennas with a wider vertical beam because your towers are on mtn peaks and some clients are same height as the tower and other clients are on the valley floor. It’s hard to use a spot beam to cover all that. In the Midwest or other flat areas I could see them being useful to spot beam the population centers. -Sean On Tue, Apr 10, 2018 at 8:29 PM Josh Reynolds <j...@kyneticwifi.com> wrote: They are great for stuff like 30/40Mhz wide, gps sync, put 4-6 on a pole in a subdivision or on a tower leg kinda thing. If anybody thought they were for something else (ie long range), they didn't read the data sheets. Lightweight, low size, low wind load, perfectly circular pattern - great spot beams. Good F/B ratio. On Tue, Apr 10, 2018, 9:12 PM Robert <i...@avantwireless.com> wrote: I recently did a couple of tests with RF horns. I was hoping for a lot and was disappointed. I was hoping that they could be colocated closer than regular sectors that I use and the crosstalk signal levels were just about the same as the shielded sectors. As far as the signals at the CPE's they were pretty good but not amazingly better for as small as the target area got reduced to. On 4/10/18 6:43 PM, Steve Jones wrote: > Can i get some non fanboy real world on these guys? Btw, i hate facebook > groups almost as much as dslreports or the ubnt forums, this is > literally the only place to get legitimate product info.