The following thesis is concerned with the development of fabrication techniques
and novel designs for self-packaged, multilayer circuits using liquid crystal polymer
(LCP) materials exclusively, given the favourable characteristics this material has
for microwave circuits.
Fabrication techniques are aimed at the production of miniature, low-profile filters.
Advanced techniques for production of interlayer via connections are investigated
and new methods proposed, with special attention at the lamination process and
production of vertical, inter-layer transitions. Results obtained demonstrate the
fabrication process is reliable for producing multilayer filters, with up to four metal
layers, and via transitions in the region of 0.2 mm diameter.
The fabrication process has been developed during this work is applied to novel filter
designs, covering dual-band filters and lowpass filters. A new structure for dual-
band filter is proposed, using folded multimode resonators (FMSIR). This structure
is validated through the fabrication of two different filters with passbands 1.2/2.4
GHz, and 2.4/5 GHz, showing deep off-band rejection.
Low pass structure covered in this thesis is based on the principle of destructive
interference and aims at low insertion loss and out-of-band rejection higher than
40 dB. Fabricated samples validate the design showing a rejection in the region of
42 dB, with a cuto frequency of 3 GHz. Its small footprint and low insertion loss
allows this type of lters to be used as cleanup filters. All the designs covered in
this work are simulated using CAD tools and then validated by measurements on
fabricated samples
