[SI-LIST] Re: antenna simulation (low RF)

• From: Ray Anderson <ray.anderson@xxxxxxxxxx>
• To: <si-list@xxxxxxxxxxxxx>
• Date: Thu, 15 Apr 2010 13:30:48 -0700
```Glenn-

Check out the paper at the following link:

http://www.eecs.wsu.edu/~pedrow/classes/ee416/Spring_2005/Quarterlys/Q2/
Written/Background/spice1.pdf

The paper is titled:

MODELING AND SIMULATION OF A DIPOLE ANTENNA FOR UWB
APPLICATIONS USING EQUIVALENT SPICE CIRCUITS

A spice model is presented for a dipole. It looks like you are on the
right trail but the devil is in the details.

-Ray Anderson
Xilinx Inc.

> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-
> bounce@xxxxxxxxxxxxx] On Behalf Of Gene Glick
> Sent: Thursday, April 15, 2010 12:44 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] antenna simulation (low RF)
>
> Hello RF swami :)
>
> What is the correct method to spice model an antenna that is receiving
> a
> signal?
>
> 1) Here's how a colleague modeled it:
>
>        ---------------| Antenna_Inductance |----------------------
>       |                                        |                  |
> Voltage_source                                |                  |
>       |                                | Tuning_Capacitor |   | Load |
>       |                                        |                  |
>       ------------------------------------------------------------
>
> Problem with this one is it doesn't match how I would expect it to
> work.
>   That is, I expect the signal at the load to be at maximum during
> resonance and fall off symmetrically above and below resonant
> frequency.
>   This model falls off correctly above resonance, since the tuning
> capacitor shorts to ground, and the inductor impedance increases.  At
> low frequency, the inductor is short, and the cap is open so the
> voltage
> source drives the load with little attenuation - not as expected.  So
I
> think this model is wrong - does not match reality.
>
> 2) Similar setup to (1), but the voltage shunts the entire RLC
network,
> with the RLC all in parallel. Also, not correct arrangement because at
> all frequencies, the voltage source is across the network.
>
> 3) Like (2), but with a current source instead.  This is closer to
> expected, but has a flat portion at low frequencies, not correct.
>
> 4) I tried a different approach here, using a loosely coupled
> transformer model.  On the primary, there's a voltage source in series
> with a tuning cap in series with the primary - that is, one big loop.
> The resonant frequency is set the same, primary and secondary, but
with
> the series RLC, low frequency response works as expected.  The
> secondary
> is modeled as parallel RLC.  Does this seem Okay?
>
> Ultimately, I'd like to predict the response of my receiving network
> (Q,
> bandwidth, etc) but the models used so far don't yield answers I
> expect.
>   Well, actually (4) looks pretty good - just not sure if that's the
> proper way to model it.
>
>
> Any help?
>
> gene
>
>
>
>
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