wilkinson combiner for antennas

Hi guys,
I am new on this forum and I am impressed about the subjects.
I intend to design a Wilkinson on a printed circuit board for 2.4GHz to combine two antenna signals (two identical antennas).
My simulation tool, tells me that the microstrip lines should be 0.75mm / 17.6 mm
for an FR4 ( Er=4.4) which has the H of dielectric=30mils.
My question: what should be the impedance of the line connecting the 100 ohms resistor to both branches ?
I intend to simulate this combiner and the two antennas on HFSS and I am worry about introducing 'garbage' because the results will be for sure ... garbage.
P.S. The antennas are identical, so I assume I should not worry about the phase
since the paths from antennas to combiner are identical ! ? Am I right ?
Thank you in advance !
HS

There should be no transmission line in series with the 100 ohm reisistors. They should connect directly to the two lines.