  We present empirical formulae that can provide dispersion and average
effective area of the fundamental mode in hollow-core antiresonant fibers. The
formulae draw on the structural parameters of the fiber, and allow one to
obtain the guiding properties over a wide spectral bandwidth, without the need
for time consuming numerical simulations. The formulae are validated by
comparing their results with those obtained using a finite-element method. We
also analyze the effects of changing the number of antiresonant tubes, as well
as adding nested elements in the antiresonant tubes on the guiding properties.
