| Home |
| Search |
| Today's Posts |
|
|
|
#2
July 10th 15, 09:54 PM
posted to rec.radio.amateur.antenna
|
|||
|
|||
An antenna question--43 ft vertical
rickman wrote:
On 7/10/2015 4:10 PM, Ian Jackson wrote: In message , writes Ian Jackson wrote: Even when the only transmission line consists the output connector of the SWR meter, and maybe an inch of internal coax, there will still BE a standing wave - but it will only be a tiny portion of longer one. There will NOT be standing waves and there will not be a voltage maximum and a voltage minimum unless there is a transmission line. Are you saying that for a standing wave to qualify as a standing wave, the transmission line needs to be long enough for there to be a voltage maximum a voltage minimum? It seems to be very much like watching a train wreck. We are fascinated by the event even though it is terrible to watch. I'm starting to get a bit tired of it though. I can only watch the train run off the track so many times. Yes, it looks like a train wreck to me also. A very big problem is people fixated on the term "standing wave". Another is people who do not understand what a transmission line is. To function as a transmission line, the conductors have to be a significant fraction of a wavelength long. The general rule of thumb is that the connection must be greater than 1/10 of a wavelength at the frequency of interest to be regarded as a transmission line. A 10 mm wire carrying a 1 MHz signal is NOT a transmission line even if the wire is RG-8 coaxial cable. A transmission line carries the electromagnetic energy in the electromagnetic field between the conductors that make up the line, not in the conductors. A very short connection can not generate an internal electomagnetic field. This is true for ALL transmission lines, whether they be parallel lines. coaxial lines, or wave guides. Standing waves only occur on transmission lines. SWR is a measurement of impedance and only depends on the impedances of the connection, be it a wire or a transmission line. -- Jim Pennino |
| Reply |
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Forum | |||
| Vertical Antenna Performance Question | Antenna | |||
| Antenna Question: Vertical Whip Vs. Type X | Scanner | |||
| Question about 20-meter monoband vertical (kinda long - antenna gurus welcome) | Antenna | |||
| Technical Vertical Antenna Question | Shortwave | |||
| Short STACKED Vertical {Tri-Band} BroomStick Antenna [Was: Wire ant question] | Shortwave | |||
Hybrid Mode
