Planar millimeter wave band-stop filters based on the excitation of confined magnetostatic waves in barium hexagonal ferrite thin film strips

Abstract

A planar millimeter wave band-stop filter based on confined magnetostatic wave ͑MSW͒ excitations in an M-type barium hexagonal ferrite ͑BaM͒ film strip was demonstrated. The device consists of a BaM film strip on the top of a coplanar waveguide with the strip length along the signal line. For zero magnetic fields, the device shows a band-stop filtering response at 53 GHz. This response originates from the excitation of confined MSW modes across the BaM strip width. The filter operation frequency is tunable with low fields. This tuning relies on the change in the MSW dispersion with field.

M-Type Barium Hexagonal Ferrite Films

“…In 2011, Lu et al demonstrated that one could significantly increase the absorption level through the replacement of the wide BaM film element with a narrow BaM film strip. 24 This significant increase in absorption results from the excitation of confined MSW modes in the BaM strip, which is explained in detail below. Figure 16 shows the configuration of such a notch filter.…”

“…10,[18][19][20][21][22][23][24] Such devices include (1) notch filters made of BaM thin films and microstrip geometry, (2) notch filters made of BaM slabs and strip-line geometry, (3) selfbiased notch filters using high-M r BaM thin films and coplanar waveguide (CPW) geometry, (4) notch filters based on the excitation of confined magnetostatic waves in narrow BaM strips and CPW configurations, and (5) phase shifters using BaM thin films and CPW geometry. This section describes the device configurations and responses of (3), (4), and (5).…”

“…16,17 The device demonstration includes both numerical 20,21,22 and experimental efforts. 18,21,22,23,10,24 The devices demonstrated include phase shifters, 21 filters, 22,23,10 ,24 circulators, 18 and isolators. 19 This chapter reviews the main advances made in the field of BaM materials and devices over the past five years.…”

“…13,14 Section 3.4 describes the fabrication of BaM thick films on semiconductor substrates by screen printing. 16,17 Section 4 reviews the demonstration of BaM thin film-based mm-wave notch filters 10,24 and phase shifters. 21 Finally, Section 5 discusses future work in the field of BaM materials and devices.…”

“…Emphasis has been placed on the optimization of deposition processes for low-loss, self-biased BaM thin films, 7,8,9,10 the deposition of BaM thin films on "non-conventional" substrates, such as semiconductor substrates 11,12,13,14 and metallic substrates, 15 the fabrication of BaM thick films on semiconductor substrates, 16,17 the demonstration of BaM-based planar mm-wave devices, 18,19,20,21,22,23,10,24 the development of BaM-based ferromagnetic/ferroelectric heterostructures, 25,26,27,28,29 and the study of multiferroic effects in single-phase BaM materials. 30 A variety of different techniques have been used to fabricate BaM film materials.…”