| Home |
| Search |
| Today's Posts |
|
#13
February 24th 04, 04:45 PM
|
|||
|
|||
On Tue, 24 Feb 2004 06:17:01 -0800, Dan Richardson
wrote: On Mon, 23 Feb 2004 17:47:15 -0600 (CST), (Richard Harrison) wrote: Not in the "grand scheme of things", perhaps, but a resonant antenna extracts more energy when swept by a traveling wave than an off-resonance conductor does at the same distance from the transmitter. So according to you, as an example, a resonate 1/4 or 1/2 monopole will extract more energy than a non-resonate 5/8-wave monopole. Enjoy your dreams, I'm QRT 73 Danny, K6MHE Hi All, As a test of modeling and actual, real data, I put this to the test: 1.) I established two full quarter wave antennas; 2.) each with a set of 48 radials; 3.) tuned to 1.7 MHz; 4.) separated them by 20KM (100 wavelengths); 5.) set one to have a source of 1000W; 6.) loaded the other at the base with a 50Ohm resistor; all in EZNEC with enough segments to hit the 500 limit. When I called for the load data, EZNEC calculated it to be: Power = 0.0008166 watts (already confirmed accurate to FCC Field trials) THEN, I increased the same antenna's length to 5/8th Wavelength and observed its load's response to the identical field: Power = 0.0001185 watts Through the simple observation of power ratios, the untuned 5/8th Wavelength antenna suffers to the tune of: -8.38dB Now, if this discussion revolves on the myopic consideration of resonant antennas, devoid of other issues like tuners, matching, lines that connect and so forth; then it is painfully obvious that NO ANTENNA absorbs ANY POWER (by virtue of the load having been defined out of the problem). This is further confirmed in the daily experience of a million yagi owners whose passive elements offer just exactly that lossless coupling. When interfaced to a real load, any SWLer will confirm through simple tuning (and through modeling) that the received power peaks through adjustment. The 5/8th antenna is no different. 73's Richard Clark, KB7QHC |
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Forum | |||
| Mobile Ant L match ? | Antenna | |||
| A Subtle Detail of Reflection Coefficients (but important to know) | Antenna | |||
| Reflection Coefficient Smoke Clears a Bit | Antenna | |||
| Length of Coax Affecting Incident Power to Meter? | Antenna | |||
| 50 Ohms "Real Resistive" impedance a Misnomer? | Antenna | |||
Threaded Mode
