smith chart question

[antenna9071]

I have one antenna (nr 1) that is matched good. the circle in smith chart goes thru 1. It has a narrow bandwidth so it is bad matched beside the resonate frequency.

If I had one other antenna (nr 2) thats is good matched for many frequencies inside the frequency band 3GHz +- f MHz. The circle in the smith chart can look at many ways but how can I see in the smith chart that the antenna is good matched for many frequencies,

If I understand it whole band that is good matched for antenna 2 would be near 1 for the circle in smith chart. so if I compare antenna 1 and 2 the smith chart can be very similary, even if antenna 1 has narrow bandwidth for the good matched frequencies and antenna 2 has wide bandwidth for the good matched frequencies.

Hope someone understand my question/questions

 

[VEBill]

I can't parse your precise question.

A basic Smith chart (unless annotated) doesn't provide any information about frequency (neither axis is frequency). The data points need to be annotated with frequency if you're to deduce anything about bandwidth. In this modern computerized world, Smith charts are often displayed on a screen and the cursor allows one to explore the curve in the frequency domain.

If you're concerned about VSWR bandwidth, a little loss can really widen things out. Any loss is probably x2 in 'Return Loss'.

The geometry of the structure can be made more complex to achieve multiple resonance points to widen the bandwidth. Simple structures tend to have simple responses. Wide structures can widen bandwidth.

All the above is a massive simplification.

 

[biff44]

The shape of a matched antenna, on a smith chart, will likely look like a 3 leafed clover--going thru the center of the smith chart over and over within the bandwidth.

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