Microwave Dielectric Resonators and RF Components in Printed Photopolymers: Permittivity, Loss and Thermal Stability

Vat photopolymerisation can produce geometrically complex radiofrequency and microwave structures, but the electromagnetic response is governed by the cured material state rather than by printer resolution alone. This review connects complex permittivity, dielectric loss, dimensional accuracy, metallisation and thermal drift to the behaviour of printed resonators, filters, antennas and hybrid RF structures. Published studies demonstrate that ceramic-filled photocurable resins can shift permittivity, that stereolithography can be used to implement microwave circuits, and that ceramic stereolithography can realise high-Q dielectric resonators with geometries that are difficult to machine conventionally. These demonstrations are not interchangeable: polymer-rich composites, sintered ceramic bodies and metallised polymer structures occupy different loss, stability and processing regimes. The central qualification problem is therefore to measure the dielectric spectrum of the actual cured state, propagate its uncertainty together with dimensional tolerances into device simulations, and verify the completed device over frequency and temperature. A minimum evidence framework is proposed that treats resin batch, cure/post-cure, filler dispersion, moisture, surface finish, metallisation and thermal history as part of the RF material identity. ER-426.