The XBSA1030 is a resonant travelling-wave longitudinal slot array antenna fabricated from precision-machined 6061-T6 aluminium. Eight slots are milled into the broad wall of a WR-90 rectangular waveguide section, each displaced alternately above and below the waveguide centre-line to achieve the correct excitation phase. The alternating ±offset geometry — governed by the slot conductance equations derived from Stevenson's theory — produces broadside radiation at the design frequency of 10.370 GHz, the standard North American 3 cm amateur allocation.
Each slot is spaced at half-guide-wavelength (λg/2 ≈ 14.2 mm) intervals along the guide axis. This spacing ensures that successive slots are excited in phase opposition, which — combined with the alternating transverse offset — results in in-phase contributions in the broadside direction. The array is terminated with a matched short at the distal end to absorb any residual travelling-wave power, minimising back-lobe formation.
The SMA female connector on the input port provides a direct 50 Ω interface to standard transverter and power amplifier outputs. The internal waveguide-to-coax transition uses a probe-type coupling element optimised for minimal reflection across the 10.0–10.5 GHz band.
This antenna is particularly well-suited for 10 GHz terrestrial QSOs, WSJT-X weak-signal digital modes, and CW microwave contesting. The pencil-shaped H-plane pattern (55° HPBW) provides sufficient beamwidth for manual antenna aiming while the narrow E-plane beam (18° HPBW) delivers the directivity needed to work paths of 100 km or more under normal tropospheric conditions.
