Computime Limited CT-EM2603 ユーザーズマニュアル

can still provide high radiation efficiency (typical 1 dBi). The radiating part of the antenna is 
located on one side of the PCB. The radiation pattern from the antenna is shown in figure 5. 
The maximum radiation is in the plane normal to the length axis of the antenna. For best 
possible omni-directional radiation the module should be oriented so that the antenna is 
vertical. In order to achieve best range the transmitting and receiving antenna should be 
oriented the same way with same polarity. Indoors reflections of the radio waves will affect 
the range.   

     

 

   
The antenna should be kept away (> 10mm) from metallic or other conductive and dielectric 
materials, and should never be used inside a metallic enclosure.   
   
Compared to lower frequencies, operation at 2.4GHz usually has a shorter LOS. However, 
the ZigBee mesh network topology provides a more flexible and reliable network topology to 
end users. The farther end device can easily be reached over a mesh network through other 
full function (routing) devices. Reflections from walls and other objects may give multi-path 
fading resulting in dead-zones. With mesh network, other nodes in the network can reach 
devices in dead-zones. Furthermore, in the case of any failure of a single node, the system 
can easily reroute to other paths. The mesh network is therefore highly recommended for 
increased reliability and extended coverage.