- Jun 10, 2004
- Redmond, WA
- Building a Sparrowhawk II
- Total Flight Time
If the antenna is properly tuned to the coax the length of the coax doesn't make a difference. Any excessive length is only a loss.And make sure your length of Co-Ax cable is a multiple of the Wavelength of the Frequency of the Antenna
I second that. -- Chris.If the antenna is properly tuned to the coax the length of the coax doesn't make a difference. Any excessive length is only a loss.
The exception to this is when you are tuning an antenna then the coax should be 1/2 wavelength electrically. In this case the meter will show the true antenna impedance.
I have to get this right in my head
If the antenna is properly tuned to the coax the length of the coax doesn't make a difference. Any excessive length is only a loss.
There seems to be a bit of a contradiction in this, you say Co-ax length doesnt make a difference, then you say an excessive length makes a loss, so there must be an optimum length?
The object of this is to match the impedance of the transmitter and antenna system to ensure as little loss as possible.
But the transciever does not see the antenna alone. the Transciever is reacting to the entire antenna system, including the coax. Coax not only has resistance( which changes with coax length, but it also has capacitance which also changes with different coax length. Resistance (Impedance), determines how the transmission line (coax)and antenna match the radio's requirement to send the greatest amount of signal to the antenna. But capacitance controls which frequency the antenna is best tuned at. Changing the capacitance of the antenna system, will alter the frequency at which your radio sees the best SWR.
Where am I goin wrong?