RO4725JXR provides a relatively low dielectric constant within a thermoset antenna-material platform. It is worth considering where wider transmission lines or antenna dimensions associated with lower Dk are useful, and where conventional glass-epoxy compatible fabrication is desirable. Its low density also distinguishes it from more heavily filled RF laminates.
Material system
Ceramic-filled hydrocarbon thermoset reinforced with woven glass
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 2.55 ± 0.05 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5 clamped stripline; direction is not separately recorded here. Source |
| Design dielectric constant | 2.64 | Typical; 1.7–5 GHz, differential phase length method; average across common constructions. Source |
| Dissipation factor | 0.0026 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5; direction is not separately recorded here. Source |
| Thermal conductivity | 0.38 W/(m·K) | Typical; ASTM D5470, 50°C, through-thickness direction. Source |
| Thermal coefficient of dielectric constant | 34 ppm/°C | Typical; -50°C to 150°C, IPC-TM-650 2.5.5.5 (modified temperature measurement); 10 GHz. Source |
Typical reported values are not a purchase specification. Process Dk, design Dk and values measured at different frequencies are not interchangeable.
Selection and design notes
- Evaluate the radiator footprint and feedline widths at the intended thickness before deciding that lower Dk is beneficial. The available board area and the required impedance may favor different core thicknesses.
- Its Design Dk is characterized over 1.7–5 GHz in the product datasheet. That is more relevant to many infrastructure antennas than assuming every Design Dk value was measured at 10 GHz.
Thickness and copper options
Use the RO4700 product thickness and tolerance table for the selected order; dielectric thickness must be separated from finished copper thickness.
Low-profile copper choices are construction specific. PIM observations require the foil and test setup stated in the Rogers datasheet.
Fabrication considerations
- Specify the copper treatment and laminate thickness together for an antenna build. Check large-panel flatness, copper balance and dimensional compensation with the fabricator, then measure a complete feed structure under the intended connector and assembly conditions.
Application fit
- Infrastructure antennas
- Low-Dk feed networks
- Printed radiating elements
Limits and substitution checks
- The selector identifies the grade as non-flame-retardant. Its water-absorption test also differs numerically from nearby antenna grades; use the actual environment and system-level verification rather than interpreting one moisture number as a weatherproofing qualification.