I. INTRODUCTION It is a well known that the current-voltage ( I − V ) characteristics of Josephson tunnel junctions can display sharp current resonances. These interesting features, called Fiske steps, appear as a result of resonant interaction between ac Josephson current and standing electromagnetic waves that can be excited in the junction [1]. A long time ago the Fiske steps have been experimentally observed in planar Josephson tunnel junctions [2]. In this time the complete theoretical description of the Fiske steps in the case of a junction with low quality factor has been done by Kulik in [3]. After that the Fiske steps have been observed in numerous Josephson coupled systems, e.g. Josephson junction arrays, [4], stacked artificial Josephson junctions [5], intrinsic high- T$_{c}$ Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+}$$_{x}$ stacked superconducting tunnel junctions [6], high- T$_{c}$ Y Ba$_{2}$Cu$_{3}$O$_{7}$$_{−}$$_{δ}$ bicrystal Josephson junction [7]. Recently, the Fiske steps have been investigated theoretically in 0 − π Josephson junctions [8] and they have been experimentally observed in 0 − π Josephson tunnel junctions with ferromagnetic barrier [9]. In ”small” Josephson junctions in which a junction size is less than the Josephson pene- tration depth λ$_{j}$ , the spectrum of the electromagnetic waves has a form: ω ( k ) = c$_{0}$k , where c$_{0}$ is the Swihart velocity, and the wave vectors k$_{n}$ are determined by a junctions size W as k$_{n}$ = πn/W , and n = 1 , 2 .... . The voltage positions of n -th Fiske steps V$_{n}$ are determined by the spectrum ω ( k$_{n}$ ) of the electromagnetic waves as [1] The magnitude of Fiske steps depends strongly on the spatial dependence of the Josephson phase difference between the electrodes ϕ ( ⃗ ρ ), where ⃗ ρ = { x, y } are the coordinates in the junction plane. In the absence of inhomogeneities a simplest way to create a coordinate dependence of the Josephson phase difference ϕ is to apply an external magnetic field parallel to the junction plane. In this case the Josephson critical current is strongly diminished but the magnitude of the Fiske step increases substantially. The magnetic field dependence of Fiske steps has been investigated in Josephson tunnel junctions with different shapes, namely, square shaped junction [10], circular shaped junction [11], quatric shaped junction [12]. In [13] the Fiske steps have been experimentally and theoretically investigated in the case of 2 V$_{n}$ = ℏ ω ( k$_{n}$ ) 2 e . (1)