Fix hyphen typo in Working with Complex Impedances
"### Power-waves\n",
"The scattering matrix as defined above has the fundamental problem that a zero-reflection coefficient does not guarantee maximal power transfer from the generator to the load [5-6]. To remedy this situation, the concept of _power-waves_ has been introduced [4]. It is a mathematical tool which is compatible with the conjugate matching condition. It also gives intuitive total power expressions, as the sum of forward and backward waves, also for complex characteristic impedances. \n",
"\n",
- "The power-waves $a$ and $b$ are defined from frequency dependent (complex) port impedance $Z_0$ [4]:\n",
+ "The power-waves $a$ and $b$ are defined from frequency-dependent (complex) port impedance $Z_0$ [4]:\n",
"\n",
"$$\n",
"a = \\frac{1}{2\\sqrt{\\Re(Z_0)}} \\left( V + Z_0 I \\right)\n",
