fencer32
Newbie level 3
antenna length and frequency dependence
Hi,
I have the following question. Suppose I take an antenna with air substrate. Therefore there are no dielectric losses. The only source of loss is conductor loss, but I can made an antenna from silver and minimize the losses.
Now, there is a theorem that states that I can match any impedance to any other impedance at a single frequency point with a lossless network composed of an inductor and a capacitor.
As a result I can match the antenna at a low frequency compared with its size. The directivity of such electrically small antenna is close to 0 dBi and since there no losses the gain is equal to directivity.
However, I've seen measurement results of electrically small patch antennas on air substrate and their gain was much lower than 0 dBi even at the point of perfect match.
So the question is: what's wrong with my reasoning?
Thanks,
fencer32
Hi,
I have the following question. Suppose I take an antenna with air substrate. Therefore there are no dielectric losses. The only source of loss is conductor loss, but I can made an antenna from silver and minimize the losses.
Now, there is a theorem that states that I can match any impedance to any other impedance at a single frequency point with a lossless network composed of an inductor and a capacitor.
As a result I can match the antenna at a low frequency compared with its size. The directivity of such electrically small antenna is close to 0 dBi and since there no losses the gain is equal to directivity.
However, I've seen measurement results of electrically small patch antennas on air substrate and their gain was much lower than 0 dBi even at the point of perfect match.
So the question is: what's wrong with my reasoning?
Thanks,
fencer32