| 摘要 |
1275324 Measuring permittivity INSTITUT MEKHANIKI POLIMEROV AKADEMII NAUK LATVIISKOI SOVETSKOI SOTSIALISTICHESKOI RESPUBLIKI 4 May 1970 [5 May 1969] 21310/70 Heading G1U In order to measure the permittivity of a block of material 4, the material is positioned adjacent three electrodes 1, 2, 3, the third being selectively connectable 6 to either of the first two, which together form a capacitor determining the frequency of a measuring oscillator 5, and the following sequence of operations is performed:- (a) Firstly the third electrode 3 is connected 6 to the first electrode 1, as shown, a counter 11 is cleared 12 to zero, the resulting frequency f 1 of the measuring oscillator 5 is mixed 10 with a reference frequency f 0 , which is designed to be less than the frequency f 1 , from a reference oscillator 9, and the counter is allowed to count cycles of the lower side band f 1 -f 0 , for a reference period, and (b) Secondly the third electrode 3 is connected to the second electrode 2, the resulting frequency f 2 is mixed as before with the reference frequency f 0 which is designed to be larger than the frequency f 2 , and the counter 11 is allowed to increase its previous count by counting cycles of the lower side band f 0 -f 2 for a further reference period. Providing that certain design conditions, discussed in the specification, are satisfied, the final count will be proportional to the required permittivity and will be independent of any errors caused by air gaps between the electrodes and the material under examination. |
