Microwave characterisation of CaF2 at cryogenic temperatures using a dielectric resonator technique

Science and Technology of Advanced Materials

2005

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

“…5 at a frequency of 16.5 GHz [7][8][9]. The losses of LiF at microwave frequencies are higher than its counterparts.…”

Section: Resultsmentioning

confidence: 99%

Section: Experimental Techniquesmentioning

confidence: 99%

Low temperature microwave characterisation of lithium fluoride at different frequencies

Science and Technology of Advanced Materials

2005

“…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].…”

Section: Experimental Techniquesmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Fundamental Material Constants in Microwave Measurement

2009

Ferroelectrics

Self Cite

Microwave characterisation of dielectric materials is vital to implement the material in communication devices and circuits. The microwave characterisation parameters are the dielectric constant, loss tangent, Q 0 × f 0 , temperature coefficient of frequency and temperature coefficient of permittivity. This paper examines the microwave characterisation data of four different dielectric materials. From several experiments on different dielectric materials, it has been concluded that the concept of using Q 0 × f 0 and temperature coefficient of frequency, as a material property will not reflect on material's fundamental behaviour. On the other hand, it has been interesting to note that the temperature coefficient of permittivity of a material is a constant irrespective of the measurement technique and hence it is a material parameter. The studies on temperature dependent permittivity will reveal the knack of a material to operate as a frequency stable circuit or device.

“…The dielectric resonator technique has recently been used to characterise various low loss single crystal and polycrystalline dielectric materials at microwave frequencies [4][5][6][7][8][9][10]. The Hakki-Coleman version of the dielectric resonator we used for the measurements of MgF 2 is shown in Fig.…”

Section: Measurement Techniquementioning

confidence: 99%

Investigations on microwave characteristics of MgF/sub 2/ at cryogenic temperatures

2004 IEEE Region 10 Conference TENCON 2004.

Mazierska

Takeuchi³

2004

Magnesium Fluoride is a hard and birefringent crystal with low refractive index and a wide transmission range. It is widely used in prisms and optical windows. We have studied the microwave properties of MgF 2 using a Hakki-Coleman dielectric resonator technique. The permittivity varies from 5.026 to 5.165 in the temperature range 15-295K and at a frequency of 32.9 GHz. The loss tangent varies from 1X10 -5 to 8X10 -5 when the temperature increases from 15 K to 295 K.