Hybrid Wideband Staircase Filters in Rectangular Waveguide With Enhanced Out-of-Band Response

Abstract

The objective of this article is to describe the design of a new family of wideband filters in a rectangular waveguide based on hybrid couplings and a staircase configuration. The use of E-plane T -junctions and E-plane folded structures is also discussed, in order to enhance the out-of-band response and the selectivity of the filter with respect to the current state of the art. The design of several hybrid filter prototypes is discussed in detail, including manufacturing sensitivity and high-power analysis. Finally, simulations and measurements for an eight-pole filter prototype are also compared, showing very good agreement, thereby fully validating both the design procedure and the new filter topology that we propose.

Compact Dual-Band and Wideband Filters With Resonant Apertures in Rectangular Waveguide

“…In this section, we propose an additional possibility for the improvement the out-of-band performance of our filter. This is essentially based on the implementation of the staircase configuration, similarly to what was discussed in [18] and [19]. To better clarify this concept, we show in Fig.…”

“…11 is only due to the four distributed resonators, since the RAs behave basically as lumped elements resonators. However, this spurious response can be very effectively reduced with the help of the staircase configuration, as shown in [18] and [19].…”

“…In order to identify the power (Watts) where the multipactor effect can be initiated, a number of simulations have been carried out with our filter structures. The detailed procedure is fully described in [19], and will not be repeated here for the sake of space. Tables V and VI show the power thresholds that we have obtained for the dual band and extended band pass RA filters.…”

“…In this context, a recent contribution can be found in the technical literature that discusses how to improve the outof-band performance and selectivity of a microwave wideband filter using a staircase configuration with E-plane Tjunctions and shorted stubs, as shown in [18] and [19]. However, even though the structure proposed does produce an important improvement of the out-of-band response and a good enhancement of the filter selectivity, it can result in rather long structures for high order filters.…”

D-Band Waveguide Diplexer Fabricated Using Micro Laser Sintering

“…Using the staircase configuration, the Channel B isolation is greatly improved to over 60 dB. This is due to the capacitive inter-resonator apertures being positioned so that the coupling between the higher order modes is strongly suppressed [41]. The staircase configuration was not used for the upper channel, as it would slightly worsen the attenuation at the lower stopband.…”