Hello,
I really spent too much time on the internet searching for a small directional antenna (not more than 15 cm) and i faild to find one. According to the websites that i visited all what i found is big antennae and is not suitable to what i want
my project is fly a small drone, the drone gonna have 4 different RF receivers from these ( hoperf.com/upload/rf/RFM26W.pdf ) the drone will fly to search for the transmitter ( this can be done by knowing the RSSI value; for example if the value is higher on the right the drone will turn to right) so in order to know the signal direction i chose to have a directional antenna but it seems like there is no small directional antenna 
, what do you think, do you have any suggestion to know the direction of the signal ?? did you see a small directional antenna before?? will the directional antenna work for this transicever?
note that the system will work in a room that has an area of (5 m x 4 m), the transceiver frequency is 433 MHz
thank you
Hi OmarAlhebsi,
The Antenna size is closely linked to the band frequency needed more so when you deal with a directional version.
We are not experts in antenna design but a quick search helped us say this.
Hi,
do you have an alternative solution? because using the direction antenna is impossible since the the drone is small
If there is a solution to know the location of the transmitter inside a room by flying a drone this will be great 
This is a project on it’s own but you could just monitor RSSI of each modules and it will give you the location.
No need for individual antennas, an Omni would still give you RSSI no ?
RSSI is not accurate at all, thats why using the directional antenna was the simplest solution ( it takes the signal from one direction only), the Omni antenna all what it does is the oppsite 
We have a product called “Indoor GPS Navigation System” which could be use for positioning.
Another system is not yet released but will rely on RSSI and we will have it in the future. (LPS Mini)
This is such a big system !, do you an idea how to do the same project with IR instead of RF in locating the transmitter, I guess IR will be better in indoor
Unfortunately we do not have experience using IR as positioning system.
, what do you think, do you have any suggestion to know the direction of the signal ?? did you see a small directional antenna before?? will the directional antenna work for this transicever?
