regarding antenna gain-need urgent reply
A PIFA antenna is working in 2.2 to 2.7 GHz band with omni directional pattern. but the measured gain of the antenna is -7dBi.
1. will it be suitable for any useful application?
i have seen some company products with negative gain. i am not able to understand the physical significance.
if anyone of you is able to give me the feedback about my antenna it will be helpful for me to rectify it.
with thanks in advance,
KBMani.
Possibly
You would have to do a link budget analysis for a specific example and include Tx power Tx gain, Rx gain, reciever sensitivity, noise figure and free space path loss.
If the Tx power and antenna gains are sufficient to support your Rx sensitivity, NF requirements over your required distance (FSPL) at your specific frequency then it will support the link........all in simple terms of course.
Theoretically the maximum average gain of PIFA is no greater than 0dBd but I have seen mobile radios on the market with antenna gain around -8dBd.
They work poorly, but the network does not reject them because other RF performances compensate for this (RX sensitivity and TX output power).
so you mean that this antenna gain is sufficient for mobile applications.right?
with thanks,
kbmani
Antenna gain depends by the system budget and sometimes depends by the type of the network.
-7dBi seems to be too low for a mobile application, to maintain a good link connection.
An omnidirectional antenna would normally be expected to have around 0 dBi of gain for matched polarization. There are many types possible and a PIFA is one.
If we assume a uniform pattern (4 pi streadians) the directivity would be 0 dB. Most omni antennas hover around this value.
The -7 dBi value you cite indicates a low efficiency and something is probably going wrong in the antenna. You may see a good (low) reflection coefficient and can be mislead into thinking that the antenna is performing well. A high loss somewhere in the feed usually shows up as a good match but with low gain which is probably the case here.
You ask if the PIFA could still work and the answer is yes with extra power or a sensitive receiver.
These kinds of gain values are also usually seen with electrically small antennas and may be a consequence of trying to shrink the antenna.