Hervé Leblond

3-D pyramidal and collective Ku band pass filters made in Alumina by ceramic stereolithography

An original 3D pyramidal geometry for a low loss and compact (10.5 mm by 10.2 mm by 2 mm) filter is described in this paper. Nine low footprint Alumina filters are manufactured in one single fabrication by a 3D ceramic stereolithography process. Thank to this technology, high unloaded quality factor resonators (above 1000) have been fabricated and associated to create a low footprint 4-pole Chebyshev filter. Its shielding has been created with a Copper and Gold sputtering technique and its input and output coplanar accesses have been etched by a laser ablation technique. The association of these 3D technologies for the collective manufacturing of many filters in one ceramic part, has led to a low insertion loss filter working around 17.5 GHz. This paper goes into details on the theoretical synthesis, design, fabrication and measurements of a Ku band pass filter dedicated to space applications. Index Terms — ceramics, 3D stereolithography, band pass filters, laser ablation, submillimeter wave filters.

Design of Microstrip Lossy Filters for Receivers in Satellite Transponders

This paper compares several designs of lossy filters for receiver subsystems in satellite transponders. The reference design is a microstrip filter made of coupled hairpin resonators. Two approaches are investigated for improving the flatness of the reference design. The first approach combines nonuniform quality factor (Q) resonators in a transversal network. The second approach uses an inline network with resistive cross couplings. Lossy filter designs are compared to the reference, considering the same specifications and the same technology. The inline network with resistive cross-couplings is finally modified for designing absorptive filters, which protect the receiver from reflected waves. All filter configurations are fabricated and measured, showing a good agreement with electromagnetic simulations.

Ultra-compact X-band SIW filter in LTCC technology using high permittivity substrate for a space application

Substrate Integrated Waveguide (SIW) provides a better Q-factor compared with the other planar techniques. Its integration capabilities and fabrication cost are other benefits that make it attractive. But SIW filters are bulkier than their equivalents achieved in microstrip technology. This paper reports on the association of two solutions to reduce size and make SIW even more attractive: LTCC technology to stack cavities and high permittivity substrate. The objective is to demonstrate the possibility to build high performance X-band filter on a ceramics through a multi-layer approach. The solution is tested on a X-band-dedicated 6th-order filter with drastic specifications for space application.

When new needs for satellite payloads meet with new filters architecture and technologies

To cope with the economical and technical demands of the market and to compete with terrestrial networks, satellite operators and manufacturers will need to upgrade their satellites and services. Nowadays, most of commercial satellite payloads are designed for a predetermined service and lack flexibility. Future communication satellites have to become more flexible and shall provide capacity at the lowest cost. The upcoming new needs lead to a major impact on the architecture at satellite payload level. RF and microwave filters are one of the most affected by the derived equipment specifications. The required out-of-band rejection close to the useful bandwidth will become more stringent (better than 40 dBc) while saving size and mass by more than 30% compared to the heavy mechanical cavities used today. Advanced technologies, like ceramic 3D stereolithography or Surface Integrated Waveguide technology presented in this paper are very promising solutions to overcome these requirements. Moreover, tunable filters could be a relevant option to simplify payload architectures by giving more flexibility on the frequency plan and/or bandwidth. Today, agile filters are not available in space equipments but some new technologies presented in this paper, such as MEMS technologies or ceramic based flexible filters, have now the capability to comply with space environment constraints. Finally, new synthesis method techniques could help saving mass (by 30% or more) of future OMUX equipments.

Compact Ku band filter based on BMT dielectric resonators made in a single part using 3D ceramic stereolithography process

A Ku band 6 pole quasi-elliptic filter based on dielectric resonators is presented. To the best of our knowledge, this is the first time that temperature stable BMT ceramic material (εr = 24.4 and tan δ = 0.95.10−4 ± 0.29.10−5 at 11.1 GHz) is associated with stereolithography process for the manufacturing of 3D parts. The proposed filter is composed of 6 dielectric resonators, their support and a dielectric negative coupling element all connected into one single ceramic part. This configuration is optimized to achieve a 1.7% pass band at 11.7 GHz which does not require any glue or advanced positioning technique for its assembly into silver cylindrical cavities. A 41% volume reduction compared to standard 6 pole TE113 cavity filter is proposed while keeping a Qu of 8500 and insertion loss close to −0.3 dB.

Compact low loss alumina band-pass filter in Ku band using layer-by-layer stereolithography technology

Based on layer-by-layer stereolithography, a small sized 2-pole filter in Ku band is designed and manufactured. Experimental and electrical performances are in good agreement with the computations performed and validate the use of such technology in the fabrication of microwave filters. Employing a standard metallization method for such structures is also confirmed. A 2-pole bandpass filter, of 35 mm area and 2 mm height, is achieved. Nevertheless, the insertion losses are excellent and less than 1 dB while the return losses are better than 20 dB. The unloaded quality factor is 1650. On the other hand, a theoretical study of a 4-pole filter centered at 17.5 GHz is also presented. Index Terms — Stereolithography (SL), resonant cavity, bandpass filter (BPF), unloaded quality factor (Qu), threedimensional (3-D) ceramic technology.

Association of HPWRs and DBRs for a High Rejection C-Band Filter With Post-Tuning Elements

This letter focuses on a new topology of bandpass filter (BPF), based on the combined use of different resonators. The filter is a C-band fourth order filter based on the association of hybrid planar waveguide resonators (HPWRs) and dual behavior resonators (DBRs). The association of these particular resonators was chosen so that the filter would benefit from their high-Q SIW cavities and intrinsic transmission zeros at finite frequencies. The present letter also suggests a method to adjust the filter response after fabrication, in order to compensate for the technological dispersion, and thus meet stringent specifications. Adjustment can be achieved by controlling transmission zeros for each resonator. The mixed filter with an embedded post-fabrication tuning elements was built on a standard ceramic substrate and tested to demonstrate the underlying concept. Experimental results agree well with simulation results.

Practical considerations on the design and optimization of substrate integrated coaxial filters

A practical approach for the design and optimization of substrate integrated coaxial filters is presented in this work. The technique is based on the electromagnetic optimization of the 3D filter by using a circuit-level model of the structure. As an example, a 6-pole filter with quasi-elliptic response and tight requirements in terms of group delay flatness has been designed, manufactured and measured. The proposed approach can be used on any cross-coupled substrate integrated coaxial filters and can help to minimize the computational effort and number of design iterations required for satisfying stringent filter specifications.

Design of a compact hybrid filter using microstrip resonators and surface mounted cavities

A novel hybrid filter design based on low-Q microstrip resonators and high-Q surface mounted cavities is presented. The proposed structure is composed of quarter-wavelength resonators coupled with metallic cavities, which include capacitive posts for reducing the footprint. A six-pole quasi-elliptic filter is designed regarding specifications for a C-band satellite equipment. The design is detailed and initial experimental results are given.