Home |
Search |
Today's Posts |
#9
![]() |
|||
|
|||
![]()
As an alternative to putting your Field Day antenna higher, consider
finding a location that will enhance lower angle radiation. 10 dB improvement over flat ground isn't too hard to come by in hilly or mountainous terrain. The best program I've seen for determining this is TA (Terrain Analysis), a DOS program which I believe you can still get from its author, Brian Beezley, K6STI. Last I heard, he'll only take orders by mail. I have the same general problem here in Oregon, perhaps even more so. My Field Day antennas and location are chosen as though I were after DX. You might be interested in the "Field Day Special", an antenna I've used for many years from here -- it might also be suitable for you. You can find the info at http://www.eznec.com/Amateur/Articles/. Roy Lewallen, W7EL Al Lorona wrote: Hi, Richard, Yeah, your reference sounds about right. On Roy's suggestion, I downloaded W6ELprop and was shocked to find what the elevation angles are for even moderate path lengths. For example, I ran the path from Albuquerque to Philadelphia and was amazed to find that the signal would have to leave the antenna and reflect from the F layer at a 4 degree angle!! That's darn near parallel to the reflecting surface! This is far, far lower than I had ever thought. Most antennas have radiation at this angle, of course, but it is usually way down from the main lobe. Even for double-hop contacts, I believe that the angle was something like 8 or 10 degrees for that same path, but I don't remember exactly right now. You cite that a 1/2-wave-high horizontal antenna has a maximum lobe at 30 degrees. Starting at Albuquerque, that 30 degrees will get you only to about Oklahoma City on the first hop. Again, this surprised me. Believe me, I am becoming disabused of my previous erroneous notions. These numbers are all for 40 meters and below. If the horizontal antenna in question is operated on a higher frequency, there's no guarantee (if I am reading the data in W6ELprop correctly) that a 30 degree incident angle will be reflected at all. I tend to grow jaded upon hearing east coast stations (I am in Los Angeles) on 40, but now I will appreciate the physics necessary to make such a thing possible. I am also going to have to put up my Field Day antenna much, much higher than previously thought. Regards, Al W6LX |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Accuracy of Antenna Testing Ranges | Antenna | |||
The "TRICK" to TV 'type' Coax Cable [Shielded] SWL Loop Antennas {RHF} | Antenna | |||
Antenna Advice | Shortwave | |||
Outdoor Antenna and lack of intermod | Scanner | |||
Ten-tec vee beam | Antenna |