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# Feed Line Results

After specifying the feed line parameters, the following results will be obtained:

Characteristic Z0

It is the “true” characteristic impedance of the transmission line obtained from the RLGC model via the K0, K1 and K2 constants. The real part of Z0 may differ somewhat from the nominal Z0 depending on frequency and losses in the line. An imaginary part will always appear in Z0 due to the non-zero losses. So, note that the true characteristic Z0 will be generally different from the “Nominal Z0” (Z0 in the cable datasheet).

True Velocity Factor

It is the velocity factor obtained from the RLGC model of the transmission line, where the wavenumber (and wavelength inside the line) is affected by losses. The velocity factor will be modified relative to its nominal value accordingly. Therefore, the true velocity factor is a function of frequency and losses in the line.

Matched Loss

Any cable datasheet contains a table of matched loss values expressed in dB/100feet or dB/100m as a function of frequency. These values correspond to the attenuation of the line when it is matched (the line has a load impedance equal to Z0). So, the Matched Loss value that is shown in the Results panel is the attenuation of the line corresponding to the selected frequency.

Total Matched Loss

It is the matched loss that would be obtained for the specified length of the cable, so the Total Matched Loss equals the Matched Loss (dB/100feet or dB/100m) multiplied by the cable length.

At Line Input

The input impedance of the transmission line will be shown as well as the reflection coefficient (Rho), VSWR and return loss. This is the impedance at the line end opposite to the end where the load/antenna is connected.

The load impedance connected to the transmission line will be shown as well as the reflection coefficient (Rho), VSWR and return loss at this line end. The load impedance will be the antenna input impedance if the “Antenna Zin” option was selected as a parameter for the feed line.

It is the power in Watts consumed at the line load or effectively delivered to the antenna port. This power will be less than the input power specified as an input parameter for the feed line if the transmission line has losses. However, the power at load/antenna will be equal to the input power in the case of a lossless transmission line.

Power Lost in Line

It is the total power lost along the transmission line in Watts.

Total Line Loss

It is the total transmission line loss expressed in decibels. It will be different from the Total Matched Loss if the transmission line is not matched.

Total Loss – Matched Loss

It is the difference in decibels between the total loss obtained and the total loss that would be obtained if the line were matched. It can be interpreted as an additional loss due to a VSWR different from 1.

It is the total power in Watts radiated by the antenna when it is fed using the power at the load/antenna end of the transmission line. The radiated power will be different from the power delivered by the feed line if the antenna itself has its own losses. The radiated power will be shown if the option “Antenna Zin” was selected as a line parameter.

Antenna Loss

It is the total power lost in the antenna structure. It will be shown if the option “Antenna Zin” was selected as a line parameter.

Antenna Efficiency

It is defined as the ratio of the antenna radiated power to the antenna input power (the power delivered by the feed line). It is expressed as a percentage as it is usual. It will be shown if the option “Antenna Zin” was selected as a line parameter.

Total System Loss

It is the total loss obtained in the antenna and feed line as a whole system.