Low temperature microwave characterisation of lithium fluoride at different frequencies

Abstract

Precise knowledge of dielectric properties of materials is required to implement the material in high frequency devices and circuits. At microwave frequencies complex permittivity (dielectric constant and loss tangent) are the two mandatory parameters prior to any design. We have identified Lithium Fluoride as a potential candidate, which can be used in conjunction with superconducting and non-superconducting parts of several microwave communication devices. Even though dielectric constant of LiF is known at room temperature there only limited data presented at cryogenic temperatures. We have used a dielectric post resonator for the microwave characterisation of the rod shaped LiF crystal. In this paper, we have reported the dielectric constant (perpendicular component of the real part of complex permittivity) and loss tangent of two LiF crystals as a function of temperature (15-290 K) at frequencies of 8 and 16.5 GHz. We have also studied and reported the temperature coefficient of frequency and permittivity. The concept of using temperature coefficient of frequency as a standard is proved to be wrong in this paper. Microwave properties of other Fluorides are also compared with the LiF crystal. q

Effect of Bismuth Borate/LiF on the Sintering, Thermal, and Microwave Dielectric Properties of Ba6−3xSm8+2xTi18O54 (x=2/3) Solid Solution

“…The microwave dielectric properties of BB glass‐added BST is given in Table II. The dielectric constant (ɛ r ) of BB glass at 1 MHz is 4.6 and that of LiF 30 at 8 GHz (at 290 K) is 8.9. Hence, a decrease in the dielectric constant of BBglass+LiF‐added BST is expected.…”

Cryogenic Microwave Dielectric Properties of Sintered (Zr0.8Sn0.2)TiO4 Doped with CuO and ZnO

“…A TE 01δ mode post‐dielectric resonator 12 loaded with the dielectric under test has been used for microwave characterization. The experimental technique used for the microwave characterization is thoroughly discussed elsewhere 13 . The experimental system consists of Network Analyzer (HP 8722C, Agilent Technology, Palo Alto, CA), a closed‐cycle refrigerator (APD DE‐204, APD Cryogenics, Inc., Allentown, PA), a temperature controller (LTC‐10, Conductus, Inc., Sunnyvale, CA), vacuum Dewar (Custom Made, Australia), a PC, and a TE 01d mode dielectric resonator.…”

Understanding the Fundamental Material Constants in Microwave Measurement

“…Among the different types of dielectric resonators, HakkiColeman dielectric resonator (HCDR) and dielectric post resonators (DPR) are commonly used to characterise rod shaped dielectric materials at microwave frequencies [8][9][10]. TE 01δ mode dielectric post resonator and TE 011 mode Hakki-Coleman dielectric resonator have been employed to characterise different crystal [1][2][3][4].…”

“…The materials we have used are Magnesium Fluoride, Calcium Fluoride (CaF 2 ) and Lithium Fluoride (LiF) and Barium Fluoride [1][2][3][4]. Some of the properties of the materials used namely MgF 2 , CaF 2 , LiF and BaF 2 are shown in Table 1 [1][2][3][4][5][6] and reference therein.…”

“…The schematic diagram of dielectric post resonator (DPR)[3].Downloaded by [Temple University Libraries] at 07:31 05 January 2015…”