Computime Limited CT-EM2503 ユーザーズマニュアル

 

 
 

 ZigBee-Ready RF Transceiver Modules 

 

 

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Page 11 of 15   

 
CT-EM250 provides an integrated antenna. The design should be effective for many 
applications requiring a compact solution containing all the critical RF parts within the 
module. Applications requiring better range may consider an external antenna or 
possibly even an external booster circuit (power amplifier). 
 
The range testing using the integrated antenna shows a typical distance of 100 m 
outdoor line-of-sight (LOS). If the application is used indoor, the range will be around 
10 to 30 m, depending on structure and building materials. 
 
The module with antenna is matched for use in the 2.4 GHz band. Due to the 
dielectric ceramic material the antenna is shorter than a normal quarter wave antenna. 
However, it 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 2. 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. 

 

Figure 2 : Integrated chip antenna radiation pattern at different orientations