For a 2 lamda slot, with both ends closed with conducting disks, with coaxial
feeder to midpoint.
for 2320 Mhz
slot length 280 mm
slot width  3 mm
tube dia    19 mm by 18 swg (0.75in)

The impedance at the feedpoint is 200 ohms
You need to construct a suitable balun.

For more details refer to Microwave Handbook vol 1 , page 4.44 onwards.
73, Pete G6KUI

73 De John, G8MNY @ GB7CIP