Home |
Search |
Today's Posts |
#7
![]() |
|||
|
|||
![]()
On Mon, 15 Feb 2010 08:01:18 -0800 (PST), Art Unwin
wrote: I have not seen the like printed any where soto me it is good stuff. This might offer a clue as to how such antennas are built: http://ieeexplore.ieee.org/iel3/4812/13333/00608613.pdf?arnumber=608613 http://www.springerlink.com/content/g215405815642611/ Plenty more under IEEE Ants and Props search. Check if your local library or college library has a subscription: http://www.ieeeaps.org http://ieeeaps.org/aps_trans/ When I model a polarization independent antenna the individual gains confuse me as each of the individual gains are some what 3 db down from the "total" gain. In other words "total" is not the addition of all the polarizations gains. If you use a circularly polarized antenna, and feed it a linearly polarized signal (either vertical or horizontal) you'll see a -3dB polarization mismatch loss. http://www.antenna-theory.com/basics/antennapol.php I find it very difficult to get my mind wrapped around that fact. On the surface it would suggest that competition types would benefit from a polarization independent antenna. Nope. According to my friends that do contesting, the major requirement of an antenna is NOT to maximize the gain in all directions. It's to reduce the gain to the side and back, where all the other interfering stations are usually located. Directionality is important or all you're going to hear are other local hams. A truely isotropic antenna is fairly useless for contesting. (Note: I don't do contesting). -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Lowe HF225 DC socket polarity? | Shortwave | |||
Polarity of 2SC1970 and 2SC1971 | Homebrew | |||
balun polarity? | Antenna | |||
BC-895 Reverse Polarity Mistake, Help! | Scanner |