Methods of producing microwave device

DETAILED DESCRIPTION The invention is a process for fabricating a microwave device comprising dielectric ceramic material selected from materials with nominal formula Ba.
sub.
2 Ti.
sub.
9 O.
sub.
20, BaTi.
sub.
4 O.
sub.
9, ZrTiO.
sub.
4 which may include additives such as Sn, e.
g.
ZrTiO.
sub.
4 (Sn), which is prepared by the process with a greatly reduced number of processing steps, relative to a conventional processing.
The dielectric material is comprised of at least 90 mole percent of a ceramic material with said nominal formula.
The remaining 10 mole percent may be inert material, binder material, etc.
In general, best results are obtained when at least 99 mole percent of the dielectric material is composed largely of Ba.
sub.
2 Ti.
sub.
9 O.
sub.
20.
Such ceramic material is useful in a variety of microwave devices including passband filters, signal source devices, band rejection filters and other microwave devices that process microwave signals.
For the purposes of this application, signal frequencies from 0.
4 to 200 GHz are regarded as microwave devices.
Dielectric materials are especially useful for resonator applications over the 0.
5-20 GHz frequency range.
The present invention will be described with reference to exemplary dielectric materials having the nominal formula Ba.
sub.
2 Ti.
sub.
9 O.
sub.
20.
Nevertheless, the principles of the invention are applicable to the other dielectric materials also.
A variety of methods have been used for the preparation of the dielectric material.
Exemplary prior art preparation procedures have been described in U.
S.
Pat.
Nos.
3,938,064 and 4,337,446, noted above, incorporated herein by reference.
One typical conventional (prior art) method of preparing the materials is illustrated by the flow chart in FIG.
1 of the drawings.
In the conventional method, appropriate amounts of starting materials that yield BaO and TiO.
sub.
2, such as reagent grade BaCO.
sub.
3 or BaTiO.
sub.
3 and TiO.
sub.
2, are mixed in a conventional manner, such as by wet ball milling.
The mixed reagents are filtered, dried, screened and reacted (calcined) at a temperature between 1000