I have a little problem and i ask help.
I would like to use antenna diversity with Si446x transceiver. I use 2 wire antenna with different polarization (one vertical and one horizontal). Also, i know that these 2 antennas must be lambda/4 far each other, but i have a doubt.
This distance (lambda/4) is between the 2 antenna connection points with the PCB or between the 2 middle points of the wire antennas?
For the possible best diversity gain it is even better if you could ensure lambda/2 distance between the antennas.
This distance should be measured between the main radiators of antennas. This could be the mid-point of the monopole-type antenna part perpendicular to the GND plane.
Thanks for the reply.
Ok for Lambda/2, but if the device must be as small as possible, for me it is better use lambda/4 as distance.
Excuse me but I don't understand your second opinion.
I have to find the points that are the perpendicular points of each antenna on the GND plane, and the difference between these 2 Points must be lambda/4 (or lambda/2)?
1. OK - understood the space limitations that drive the selected distance between the antennas. It is recommended to maximize it as much as you can until lambda/2. Lambda/4 is the min recommended distance.
2. You have to find the main radiator parts of the antennas, and then the distance between them should be kept as lambda/4...lambda/2. For a monopole-type antenna, the main radiator part is the one which is perpendicular to the GND plane.
1. So, i can choose a value between lambda/4 and lambda/2, but if it is closer to lambda/2 it is better.
2. Ok.. ad example, in the picture, this distance that must be closer lambda/4 is the distance D.. is it right?
Ok, i understand... thanks!
But, last question, if i wanted to use wire PCB antennas, the distance D that i have to respect, is it the following,right?
Ok, i repost the figure previous one and I zoom the interested zone.
Now i think taht it is correct.