Home |
Search |
Today's Posts |
#9
![]() |
|||
|
|||
![]() "Bob Bob" wrote in message ... Hi Ken Note when I modeled the 16 element I did so as a series of dipoles fed in phase rather than use the coax/crossover design. I felt like checking your statement about being unable to receive in the front yard. At around 45 degrees down from the antenna the NEC2 output says that you'll get a lobe between 20 and 30dB down from an isotropic (or 35-45dB down from the max gain) I'll admit my near close in signal theory doesnt really exist but a path of 800m has about 106dB of loss. If you knock that back to 12 metres (6dB every time you halve) you have about 70dB path loss. If you then take a WAP kind of power level of around 10dBm the RX signal at 12m with a halve wave is going to be around (10-70-25) -85dBm. This kind of corelates with the lowest usable signal for WiFi! There ya go! I like the URL you sent as being more predictable/easier to construct that using bits of coax. Keep in mind that progressively longer and longer colinears are more and more critical to build and the construction method that is being used is not really optimal in the area of spacing between elements. You could probably pick a much better design. I think however that you need to sit back and consider what you are trying to achieve. Are you setting up a personal WiFi LAN for others to use or just for specific contacts? If you are wanting to work in one direction (or use a rotator) it might be more effective to use a corner reflector and maybe 4 elements in phase. This will be much less critical in construction. Remoting the WAP will make a lot of sense too as you'll lose the line loss! Comments? Cheers Bob That's great info, Bob - btw my router puts out +20dbm and the background noise level in the receiver @ 2.422ghz is -97dbm +/- 2-3db.... As far as my purpose, I'm trying to get access when I go to a park to go /p on 40m. I want to be able to access the DX cluster & HF Pack users as well as check e-mail. I did a little research and the antennas I bought on eBay are 7dbi gain with, of course no feedline losses. No matter how much I crunch the numbers, I just can't find a more cost effective system. Ken KG0WX |
Thread Tools | Search this Thread |
Display Modes | |
|
|