Wireless Cam's - Antenna Range

[wgriffith74 0]

I work for an auction and have just came into the IT position. MGR wants to increase # of camera's and correct problems of unwatchable ones. Current system was custom built by previous IT Admin. My first question is Antenna Range. Previous system is running some wireless IP Cam's (TrendNet). There is a 2.4ghz 15 dBi Yagi Antenna (connected to wired router, which connects to DVR) pointed at them (4 Camera's) but it is only able to pickup 1 or 2 of the cam's. Cam's are mount on light pole (inside camera box), with extension cable coming from cam attached to rubber duck antenna's mounted on pole. When it comes to antenna's I have been reading like crazy and unfortunately it is all starting to get all mixed up in my brain. Now if I am not mistaken a rubber duck antenna only emits a 2.2-2.8 dBi. Should I increase the antenna size to beef up the dBi on the Camera to be able to transmit back to the Yagi Antenna? The distance from Yagi to Rubber Duck Antenna's is about 250-300ft.

 

I have thought of wiring the cams to a switch attached to an Access Point and then pointing a Directional Flat Panel towards the Yagi and to further increase my Camera coverage in future installs.

 

Thanks for any thoughts or advice.

[ssnapier 0]

Ok, first things first. Do you have rock solid line of sight? Bear in mind that LOS for this type of application is not just a straight line. The RF envelope is football shaped, and if you have any significant portion of that envelope obstructed, it will cause issues. Here is a picture to illustrate ideal LOS:

 

 

Now, about antenna gain the higher the gain the more chance you have of picking up weak or less than ideal signals. With an omnidirecitonal antenna (like your rubber duck) the advantage of a low gain is the ability to adjust for antennas that are not at the same height. The antenna will broadcast in all directions and have a wide enough vertical beamwidth to talk with a distant end that might be at a higher or lower elevation. If you get a higher gain omni (above 6dBi) you will be able to go farther but it is much more critical that the antennas are at the same (or very close) elevation.

 

With a Yagi antenna your gain affects the width of the signal both horizontally and vertically.

 

If you are using a cable from the radio to the antenna it needs to be the largest most efficient cable you can deal with. I generally like to use a minimum of LMR-400 Utlra Flex. If it is farther than 5 feet, LMR-600 will help keep your signal going out the antenna instead of being wasted in the cable.

 

Here is a rather detailed article that goes into a few more details in case I did not explain it very well:

 

http://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/82068-omni-vs-direct.html

[wgriffith74 0]

Thank you for the response.

My LOS in a straight line is unblocked.... however from the Yagi to the rubber duck there is another light pole that would affect the Horizontal signal. Vertically, depending on how big the Fresnel Zone is should be no issues. Antenna's are approx same height (+/- 1') about 20' from the ground.

 

If I was to replace the Omni-directional antenna's with a 1 bi-directional antenna, how could I link all of the Camera's antenna into one? Cloud Router? Access Point? Or is there a simpler way? Would the other light pole affect a bi-directional antenna as well?

 

Thanks

Wayne