To deal with the imaginary part, an old method is to use a reactive element, like a capacitor or inductor, to cancel it. Of course, at those frequencies and wide-bands, you need a more complex analog reactive impedance filter, in a quite small size.

In relation with the real part of impedance, simple designs are usually done for one central frequency, assuming narrow band. However, there are wide band adapter techniques, that use a fading, or gradually changing, kind of line, so you do not have an abrupt impedance change. The point is to avoid wave reflections.

You should take a look at the classical text on this is subject:

Microwave Filters, Impedance-matching Networks, and Coupling Structures

by George L. Matthaei, Leo Young, E. M. T. Jones

Of course, there should be today another lighter and updated text on the same subject

The solution you have tried is not a bad one. The reactive impedance is small compared to the resistive impedance, so doesn't affect the match much. If you want to make it better you may be able to tune it out with reactive stubs, which are short open-circuit or short-circuit transmission line sections in series or parallel with the feed line, which are the microwave equivalent of capacitors and inductors.

Mattaei Young and Jones can be downloaded free as a pdf from the internet.

I think the best real impedance to use is the geometrical mean, not the arithmetic mean, but in your case there is not much difference.

The reflection from your antenna will be better than -10 dB, maybe -14 dB, either of which is what some antennas aim at, meaning that less than 10% or less than 4% of the power is wasted, respectively.

Look up the "Smith chart" and plot your impedance on it. It will show you how the real and imaginary parts of the impedance affect the match. If you read about using it to match circuits you can use it to find out how to tune out the imaginary parts, and which real impedance is best to match to over the band.

Fernando Lepe Casillas Thank you so much for your kind answer and book recommendation, Sir. I am not familiar with matching networks for ultra-wideband antennas so I will definitely study the topic more. Have a great day, Sir.

Malcolm White Thank you for your kind answer every time, Sir. I really appreciate it. I did try with that and it works. I am confused in this case because this antenna is ultra-wideband, but I am looking getting more clearer concept of it from the book that you recommended. Thank you and have a great day, Sir.