If you're worried about being discriminatory in your own circle, simply look at the circle as a group of friends. Then, the discrimination is simply a limit on who you'll have as your friends, which is undeniably a good thing.
If you're worried about being discriminated against, then you can form your own circle, and you have the option to make it a men-only circle. Why do you want to intrude into a social space where you're not wanted?
If the participants are discussing business-related things affecting you during their circle, then you have legal rights to be allowed to participate, regardless of whether the discrimination is gender-related or not. It would be good advice to avoid such topics during circle. If you're worried that a circle from which you're excluded is doing so, you can talk to a lawyer to find out what those rights are and whether it will be wise and useful to pursue them.
Ultimately, though, you need to remember that some people feel strongly that some mysteries are gender-related and therefore it is not appropriate to have men (or women, depending) in attendance. It's not a plot to keep you out or to make you feel bad, but rather quite an ancient method of exploring certain mysteries that only apply to one sex (e.g. menstruation).