Loop Antenna Radiation pattern

loop antenna radiation pattern

Hi all!
I'm designing a small circular loop antenna (single turn) in CST MWS.I'm just very confused about the radiation pattern i'm getting. I've been reading in textbooks that the radiation pattern of the loop antenna is like a dipole and must be in the plane of the antenna, i.e. the direction of the max radiation is NOT through the loop. But what i'm getting is the exact opposite.I've attached a printscreen of it in the pdf file below.

Also, to satisfy the small loop condition, I designed it so that its diameter is lambda/10: f=1GHz=>Lambda=300mm=>radius=15mm
but somehow the resonant frequency is at about 2.7GHz?

I tried increasing the dimensions, so that the resonant frequency is reduced.It did, but it never obeyed the lambda/10 rule(it was not what i expected to be). For example for a radius of 47mm, the resonant frequency is 875MHz.

Any help is greatly appreciated.

Cheers
pari

loop antenna radiation

I don't see, how a resonance at lambda/10 could be achieved without additional tuning elements. The input impedance can't be real.

Also the maximum radiation direction normal to the loop, as observed, can be concluded from simple symmetry considerations.

P.S.: O.K. That's true for the magnetic near field. Far field radiation direction is in the loop's plane, with a zero normal to the loop. However if you make the loop larger than lambda/10, it act's more like a folded dipol and get's a completely different radiation pattern.

loop antenna,radiation

Please share your design. So that I can help you.