FMM28
Newbie level 5
Hi
book title: Microstrip Filtersfor RF/Microwave Applications, by JIA-SHENG HONG M. J. LANCASTER
In chapter 5 of the book, the design of Stepped-Impedance, L-C Ladder Type Lowpass Filter is described. A third degree lowpass prototype with Chebyshev response is chosen and LC parameters are calculated.
up to here, it is all OK...
for realization of Microstrip equivalence, it specifies the ε_r and thickness of the substrate and then it says:
"Following the above-mentioned considerations, the characteristic impedances of the high- and low-impedance lines are chosen as Z0L =93 ohms and Z0C = 24 ohms"
and it uses Z0L and Z0C to calculate the initial length of microstrip sections.
my first question is: how Z0L and Z0C have been calculated? as far as i searched, the formulas for calculating impedance of microstrip line depend also on the width of the line. but at this stage of the design the width is not known yet and is to be calculated later.
the pages of the book are attached: View attachment Pages from Microstrip-Filters-for-RF-Microwave-Applications.pdf
my second question is regarding equations 5.2 and 5.3 in the attached file. where do they come from?
thanks in advance for your kind help
book title: Microstrip Filtersfor RF/Microwave Applications, by JIA-SHENG HONG M. J. LANCASTER
In chapter 5 of the book, the design of Stepped-Impedance, L-C Ladder Type Lowpass Filter is described. A third degree lowpass prototype with Chebyshev response is chosen and LC parameters are calculated.
up to here, it is all OK...
for realization of Microstrip equivalence, it specifies the ε_r and thickness of the substrate and then it says:
"Following the above-mentioned considerations, the characteristic impedances of the high- and low-impedance lines are chosen as Z0L =93 ohms and Z0C = 24 ohms"
and it uses Z0L and Z0C to calculate the initial length of microstrip sections.
my first question is: how Z0L and Z0C have been calculated? as far as i searched, the formulas for calculating impedance of microstrip line depend also on the width of the line. but at this stage of the design the width is not known yet and is to be calculated later.
the pages of the book are attached: View attachment Pages from Microstrip-Filters-for-RF-Microwave-Applications.pdf
my second question is regarding equations 5.2 and 5.3 in the attached file. where do they come from?
thanks in advance for your kind help