The center-feed in a single-layer slotted waveguide array[1]-[3] is one of the key components in polarization division duplex (PDD) wireless systems. Two center-feed arrays with orthogonal polarization and boresight beams are orthogonally arranged side-by-side for transmission and reception, simultaneously. Each antenna has extremely high XPD (almost 50 dB in measurement) and a very high isolation (over 80 dB in measurement) between two arrays is observed provided the symmetry of slot arrangement is preserved [4]. Unfortunately, the area blocked by the center feed causes high sidelobe levels. This paper proposes the ridged cross-junction multiple-way power divider for realizing blockage reduction and symmetrical slot arrangement at the same time.

Ball Grid Array packages in which I/O pins are arranged in a grid array pattern realize a number of connections between chips and PCB, but it takes much time in manual routing. So the demand for automation of package routing is increasing. In this paper, we give the necessary and sufficient condition that all nets can be connected by monotonic routes when a net consists of a finger and a ball and fingers are on the two parallel boundaries of the Ball Grid Array package, and propose a monotonic routing method based on this condition. Moreover, we give a necessary condition and a sufficient condition when fingers are on the two orthogonal boundaries, and propose a monotonic routing method based on the necessary condition.

The authors propose a single-layer hollow-waveguide 8-way Butler matrix. All components of the Butler matrix are in a single layer which contributes to low-cost fabrication. To reduce the length of the couplers, a step structure is installed in the coupled region. 50% length reduction is obtained in comparison with the conventional design using reflection-suppressing posts in the coupled region. The total size of the matrix is 17.1λg6.0λg. The full structure of the matrix is fabricated by hollow waveguides at 22 GHz band and the total measured loss is only 0.25 dB.

In this paper, a three-way divider is proposed for a partially-corporate feed in an alternating phase-fed single-layer slotted waveguide array. The divider is placed at the middle of the feed waveguide and reduces the long line effects; the frequency bandwidth is doubled. It is a kind of cross junction with one input port and three output ports; most of the power is equally divided into the right and left halves of the feed waveguide while the rest of power goes straight into the center radiating waveguide. Based upon the moment method design of the three-way divider, an inductive post is introduced for wide band power dividing control to the radiating waveguide. Reflection is below -20 dB over a wide bandwidth of 24.3-26.3 GHz, and the range of power dividing ratio ranges from 1/43 to 1/4. The amplitude and the phase from the two output ports to the feed waveguide are well balanced, and the differences are less than 0.1 dB and 5.0 degrees, respectively. The MoM analysis and the wide band design are verified experimentally in the 4 GHz band.

The reflection characteristics of large alternating-phase fed single-layer waveguide arrays with center-feeds are investigated to identify the mechanism for bandwidth narrowing effects. Firstly, the overall reflection for the whole array is analyzed by FEM and fine agreement with measurements is demonstrated. It is deviating from the conventional prediction based upon a simple sum of reflections from components in the array, such as the multiple-way power divider, the slot waveguides and the aperture at the antenna input. Careful diagnosis reveals that the mutual coupling between the alternating phase waveguides via external half-space is the key factor in reflection accumulation. Amongst all, the slot with strong excitation whose position depends upon the aperture illumination design produces the dominant contribution in the mutual coupling.

A mechanical phase shifter is designed for beam scanning in co-phase fed single-layer slotted waveguide arrays. The multiple-way power divider in this array consists of a series of π-junctions with one guide wavelength spacing in a feed waveguide. The movable narrow walls placed between the π-junctions perturb the guide wavelength as well as the phase of output ports. Method of Moment (MoM) analysis for one unit consisting of one movable plate and two junctions is conducted to estimate the available phase shift as well as the degradation of reflection. A phase shift of 86 degrees is predicted between two π-junctions under the condition of reflection below -20 dB; experiments at 4 GHz confirmed the design. The beam scanning capability of the arrays is also surveyed and the beam-scanning of about 10 degrees is predicted.

The authors propose a novel 3-way power divider named a planar cross-junction, which is used as the center feed for single-layer slotted waveguide arrays. A feeding waveguide consisting of a cascade connection of these dividers is placed at the middle of radiating waveguide in a single layer. The length of radiating waveguides is halved; the long line effect in traveling wave operation is halved and bandwidth is widened. One divider as a unit is designed by Galerkin's method of moments to suppress the reflection and to control the amplitude and the phase of the divided power into two radiating waveguides on both sides of a feed one. Two types of the cross-junction with a different divided power ratio are designed and tested by experiments in 4 GHz band. The mutual coupling effects between two adjacent cross-junctions as cascaded in a feeding waveguide of the array are predicted to be small enough; units designed here are directly applicable for a multiple-way power divider.