Broadband Slot-Type Bruce Array Fed by a Microstrip-to-Slotline T-Junction

In this letter, the slot-type Bruce array is proposed and investigated based on its wire counterpart. A broadband microstrip-to-slotline T-junction is employed to feed the antenna because of less radiation loss and the planar structure without air bridges compared to the slotline-fed and the coplanar-waveguide-fed cases. A 5-6 GHz prototype antenna having seven radiating slotline segments is designed, implemented, and tested. A wide operating bandwidth, moderate gains, and satisfactorily low cross-polarized radiation are observed, verifying the feasibility of the proposed design.