Magnetically tuned Zn2Z filters for the 18-40 GHz frequency range

Magnetically tunable filters operating in the 18-26.5 and 26.5-40 GHz frequency ranges have been constructed with spherical single crystal Ba
3
Zn
2
- Fe
24
O
41
(Zn
2
Z) resonators. Substantial reduction in the external magnetic field required for resonance (H
o
) has been achieved by making use of the large anisotropy field (H
a
) of Zn
2
Z. The design and performance of two-resonator Zn
2
Z filters which tune the 18-26.5 and 26.5-40 GHz frequency ranges are described. By using measured values for the saturation magnetization (M
s
), H
a
, and resonance linewidth (ΔH), the calculated filter 3 dB bandwidth (BW) and loss are 220 MHz and 6.4 dB respectively at 26.5 GHz. Experimentally measured filter performance characteristics reported herein are in substantial agreement with these calculations.