Ali Khalil

Quasi-Elliptic and Chebyshev Compact LTCC Multi-Pole Filters Functioning in the Submillimetric Wave Region at 150 GHz

This paper proposes, for the first time to the best of our knowledge, two challenging LTCC multi-pole bandpass filters operating at 150 GHz for radioastronomy applications. Low-temperature co-fired ceramic (LTCC) technology is employed to realize these filters because it assures the high precision and compactness needed at this high frequency. The two filters are optimized by 3-D electromagnetic simulations and are validated by experimental results. Different positive and negative couplings, which are achieved by different coupling apertures, are studied. The five-pole Chebyshev filter has 8.4 dB of insertion loss in a 1.31% fractional bandwidth for 6.7 mm 2.45 mm lateral dimensions. The fourpole quasi-elliptic filter is conceived to decrease insertion loss by decreasing the number of resonant cavities while conserving the same selectivity by introducing two transmission zeros around the passband. Beside 5.5 dB of insertion loss, this filter occupies a more compact circuit area (3.32 mm 2.37 mm) and insures a very good spurious free region (16 GHz) around 150 GHz. Experimental results are in good agreement with the theoretical ones and validate the use of LTCC technology at such high frequencies over 100 GHz.

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.

150 GHz Band-Pass Filter Using LTCC Technology

A low temperature co-fired ceramic 150 GHz bandpass filter is, for the first time, designed and manufactured. Experimental electric performances are encouraging and validate the use of LTCC technology at submillimeter wave range. A Chebyshev 2-pole bandpass filter is achieved, with 1.6% bandwidth and 4.6 dB insertion loss. The unloaded quality factor is found to be 290.

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.

Quasi-elliptic 150 GHz highly selective LTCC filter

In this paper, and for the first time to the best of our knowledge, a very challenging 4-pole quasi-elliptic filter in the submillimetric wave range is studied and fabricated by the LTCC technology. The proposed 4-pole filter, centered at 150 GHz with 2 GHz band pass, is described and the coupling apertures used to provide the required positive and negative couplings are studied. The measured response is in very good agreement with the predicted behavior with a central frequency of 149.7 GHz (0.2% variation) and a 2.02 GHz band pass. The obtained manufactured filter is compact in size (3.32 mm x 2.36 mm x 0.6 mm), has a high performance with 5.5 dB insertion loss at the central frequency and a transmission attenuation over 20 dB for fo ± 1.6 GHz. Index Terms Low temperature co-fired ceramic (LTCC), quasi-elliptic filter, resonant cavity, submillimeter wave range.