Recent content by ffjonas

Thanks for the quick reply. The two transmitting antennas are theoretically in phase. However, there is a very little difference in phase due to limitation of the hardware. The receiver antenna does have 3D coils which are oriented orthogonally.

The receiver antenna is placed on the horizontal plane. The ideal case is that it can be oriented randomly without suffering any negative effect. I am still not clear about the reason why a non-optimal coupling of receiver antenna can affect superposition of two antennas (I mean, when...

I just did the experiment with pointing two transmitting antennas upwards and tried to check the superposition of two antennas. The results do get better. The difference gets smaller. :) One question: If I place the two transmitting antennas this way, will they affect each other?

Hey, thanks for your reply! It was very helpful. :) I changed one transmitting antenna to a more powerful one in order to create a stronger magnetic field. The other remains. The issue still remains. I placed the two transmitting antennas in parallel to the board.

Hey sophiecentaur, the coils are oriented in x, y and z directions, which are at right angles to each other. I do not quite get what you mean by "else the directions of the H fields will be all over the place."

Hey, :) I just did what you suggested (Have them mounted at right angles to each other). The error became smaller at position, like at the 40 degree component of each. :) However, when I was trying some other positions, the results do not look good. I am not sure if I have presented it...

Hey, because the two antennas are connected to a PCB board and driven by the board, I can monitor the voltage of two output signals related to these two antennas. They are connected to the same data which needs to be transmitted. But they can be controlled via software to activate one or the...

Plus, when just one antenna is powered, the other one is terminated. And I also checked in the scope, which shows that two frames do not overlay. There is 1s break between every activation. :)

Hey, thanks very much for your reply. I just an experiment, in which I separate two transmit antennas further (90cm). At some positions, it does not work well. At these positions there is a quite big difference between the two values I want to compare. As a matter of fact, I can not...

I did the experiment again and the values still do not match. What if the mismatch is caused by coupling between two antennas, what should I do to alleviate this undesirable affect? Thanks!

Hey, The two transmitter antennas that I am using are LF antenna (125KHz). They are directional antenna: just wind turns of wire on the ferrite rod and then connect a capacitor to tune it to desired frequency. The diagram is shown in the attachment. Steps: 1)Activate A1 (the 1st...

:) I have a device which can detect magnetic field generated by the two antennas. I was trying to compare the combined magnetic fields of both antennas with the magnetic field of a single antenna. So the combined magnetic field at the third step is supposed to be the vector sum of the...

One question: will antenna coupling problem affects the superposition of two antennas when they are placed two close, thereby I can not really apply the principle of superpostion here? Looking forward to your reply! Fan

Hey all, currently I am working on a project, which uses the principle of superposition of two antennas. I placed two antennas on the plane and make sure that they are oriented identically. The distance between these two antennas is around 51cm. I did an experiment, in which I firstly get the...