guide wavelength การใช้

Here " k " is the wavenumber due to the guided wavelength along the transmission line.
This is " half " of the guided wavelength ? = 2? / k for the frequency ?.
For example, at a frequency ? = 20 MHz ( free space wavelength of 15 m ) in a transmission line whose velocity factor is 2 / 3, the guided wavelength ( distance between voltage peaks of the forward wave alone ) would be ? = 10 m.
For instance, if the filters are of the iris-coupled type then the iris nearest to the filter junction of filter A is placed ? gb / 4 from the junction where ? gb is the guide wavelength in the passband of filter B . Likewise, the nearest iris of filter B is placed ? ga / 4 from the junction.