# Simple model for a loop antenna for LTspice simulation

I came across the following circuit on net which is a simple RF/cellphone signal detector:

Before I build and try I decided to simulate it in LTspice as follows:

I'm stuck at point about modelling the loop antenna for the simulation. You can see I put ??? question mark there in above schematics.

What type of source should I place at ??? to mimic the antenna? Should I use a 1GHz sinusoidal voltage signal source or a current signal source at 1GHz for instance? And what would be a realistic amplitude or frequency of the signal for a cell phone nearby like 5 10cm apart from the antenna?

Edit:

Now what can we say about the model for the antenna coupling?

I used a current source with 1uA amplitude and 1 GHz freq. Coupling done by a transformer above with 1uH inductances and 0.01 coupling factor.

Would this be realistic for a loop antenna for 15 cm diameter 10 cm far away from a typical cell phone?

Ideally, you'd put an inductor there that represents the inductance of the actual antenna. You would weakly couple that to a second inductor that is driven by a current source.

If you have inductors L1 and L2, you might couple them with a statement like

K1 L1 L2 0.01