Bandwidth

[arya-_-]

I am designing a antenna in CST studio suit and I want to increase the bandwidth of the antenna, but when I'm doing any changes in the design it is affecting the impedance, can anyone help me out on this

 

[aliarifat794]

Use CST’s optimization tools to fine-tune the design parameters. This will let you systematically improve the bandwidth of your antenna while maintaining proper impedance matching.

 

[D.A.(Tony)Stewart]

Are you considering an increase by % or by octaves?

 

[biff44]

Antennas, generally speaking, are formed of line lengths.

If they are made of transmission lines, they act as transmissions lines do and have limited bandwidth (see the whole topic on Richard's transformations).

If instead you make the elements out of quasi lumped elements, they will act more "lumped element like", and have bigger bandwidth.

For instance, the one on the right has a bigger bandwidth, since it approximates an inductor and then a capacitor lumped element. the one on the left is just an open circuited quarter wave stub, which behaves entirely like a radiating transmission line element.

and another benefit, the one on the right has a bigger open circuit fringing capacitance due to its wider microstrip width--further making it look like a lumped capacitor

you see this sometimes in patch antennas that look more like a dumbbell shape than a square. The dumbbell acts more like a lumped element, and gives you bigger bandwidth