Antenna gain primairily comes from boom length…nothing else.

The number of elements is almost negligible in aspect to gain. (The amount of elements do highly effect things like FB/FR/SWR bandwidth etc)

Above is to provide an insigth of which amount of gain one should expect for a specific boom length.

Its was made for 27,555 Mhz and about 30 NEC confirmed antennas were used as input.