IFA VS monopole antenna

[by88]

hi guys,

from my understanding iFA is just monopole with a trace connected to ground.
the trace act as a inductor to tune the input impedance. so we can play with the length and width of the trace connected to ground to tune the antenna input impedance.am i wrong about this
are this 2 type of antenna having the same radiation pattern?
which is more easy detuned by human body?

thanks

 

[vfone]

Better comparison of the IFA is with an asymmetric dipole antenna.
The length and the width of the feed trace could be used to change the input impedance of IFA. Also the length of the bottom trace connected to the ground could change the input impedance. Those 3 parameters could adjust to 50 ohms the input impedance of the IFA without using any other external components.
The ground dimension and the position of IFA on the PCB dictates the antenna pattern.

 

[by88]

Better comparison of the IFA is with an asymmetric dipole antenna.
The length and the width of the feed trace could be used to change the input impedance of IFA. Also the length of the bottom trace connected to the ground could change the input impedance. Those 3 parameters could adjust to 50 ohms the input impedance of the IFA without using any other external components.
The ground dimension and the position of IFA on the PCB dictates the antenna pattern.

how bout detuning effect. which one more easy to get detuned due to human body.

 

[FvM]

IFA can be described a monopole with built-in impedance transformation. Because any monopole doesn't exist without ground plane, it's more appropriate to analyze it as asymmetrical dipole,.

Secondly IFA usually appears as electrical small antenna (length < lambda/4). Detuning sensitivity mainly depends on antenna bandwidth respectively shortening factor. Therefore I'd expect similar detuning sensitivity of same size antennas, either monopole with external matching circuit or IFA.

 

[oceanblack]

Based on my previous experience on proejcts, Monopole is easier detuned by human body.

 

[by88]

Based on my previous experience on proejcts, Monopole is easier detuned by human body.

u know any theory behind this? why monopole easier detuned compared to IFA

 

[vfone]

The answer to your question is in #4 where is mentioned that detuning sensitivity mainly depends by antenna bandwidth.
IFA has relative high bandwidth, an optimized IFA have better than 10% bandwidth.