  Superconducting Quantum Interference Filters (SQIFs) are arrays of
superconducting loops of different sizes including Josephson Junctions (JJ).
For a random distribution of sizes, they present a non-periodic response to an
applied magnetic field, with an extended linear regime and a sizable field
sensitivity. Such properties make SQIFs interesting devices to detect the
magnetic component of electromagnetic waves at microwave frequencies. We have
used the highly scalable technique of ion irradiation to make High Tc SQUIDs
and SQIFs based on commercial YBa2Cu3O7 films, and studied their properties.
Both display optimum performances as a function of temperature and bias
current, that can be understood in the frame of numerical simulations that we
developed. The role of asymmetries and spread in JJ characteristics (routinely
found in HTSc technologies) is described : ion irradiation based devices appear
robust against them. We finally present results on SQIF made with 2000 SQUID in
series, showing a transfer function dV/dB ~ 1000V/T .
