Optenni Lab offers tools for estimating the obtainable bandwidth from antenna impedance curves using the bandwidth potential  and Q factor approaches.

Bandwidth potential

In the bandwidth potential calculation, Optenni Lab constructs for each frequency a two-component matching circuit and calculates the obtained maximal impedance bandwidth. It repeats the analysis for all frequencies and gives a curve that shows what kinds of bandwidths can be obtained at different frequencies.

With the bandwidth potential calculation you can

• Compare differently matched antennas to show which one offers best obtainable bandwidth
• Verify if the bandwidth is large enough for the desired application even if the antenna was not originally resonant
• Check on which frequencies the antenna gives maximal bandwidth

The bandwidth potential calculation speeds up the antenna design process. You can quickly estimate the obtainable antenna bandwidth from a measured or simulated prototype without explicitly tuning the antenna to resonance at the desired frequency range. If the bandwidth is not sufficient, you can modify the design and calculate the bandwidth potential until the specifications have been met. Then you can tune the antenna to resonance by changing the antenna geometry or by generating a matching circuit with Optenni Lab.

Optenni Lab offers two ways of calculating the bandwidth potential:

1. Standard: At each frequency, the impedance is conjugate matched to the generator impedance and the symmetric impedance bandwidth is recorded at a desired matching level.
2. Optimized: At each frequency, the symmetric bandwidth through a two-component matching circuit is maximized and this bandwidth is recorded.

Example of standard and optimized bandwidth potential. The vertical axis is relative bandwidth as a percentage of the center frequency.

Q factor estimation

In addition, Optenni Lab can estimate the antenna Q factor based on the impedance data directly. This method is less accurate than the bandwidth potential calculation especially if the impedance data is noisy or if multiple resonances are present.

More information

• J. Rahola (invited), Bandwidth potential and electromagnetic isolation: Tools for analysing the impedance behaviour of antenna systems, Proceedings of the EuCAP 2009 conference, Berlin, March 23-27, 2009.

• A. D. Yaghjian and S. R. Best: Impedance, Bandwidth, and Q of Antennas, IEEE Transactions on Antennas and Propagation, Vol. 53, 2005, pages 1298-1324.