Le 8 août 2009 11:54, i8cvs[email protected] a écrit :
Hi Jean, VA2SS
Since the ELK antenna is a log-periodic antenna covering a wide band from 2 meters and 70 cm it is difficult to connect 2 ELK in phase and gain 3 dB in 2 meters and 70 cm as well.
Also it is difficult to connect 2 ELK with a phase offset of 90° to get circular polarization in 2 meters and 70 cm
I would prefere to put one ELK horizontal and the other one vertical feeding each antenna with an individual coax line.
Using a coax relay in the shack you can immediately switch from the Horizontal to the Vertical polarization.
About the distance between the antennas over the plastic boom the distance is a function of the antenna gain and higher is the gain (in order do not overlap the aperture area of each antenna) larger must be the distance between booms
Since the gain of the ELK in the lover 2 meters band is 6.6 dBd over the dipole or 6.6 +2.14 = 8.7 dBi over the isotropic then the aperture area wich is a circle perpendicular to the antenna boom can be computed using the following formula:
/ 2 G x /\ Aperture area= ---------- 4 x Pi
Since G= 8.7 dBi = 7.41 in power ratio
2 7.41 x 2 Aperture area= -------------- = 2.36 square meters 4 x 3.14
A circle with a geometrical area of 2.36 square meters has a radius of
\ /-------------------- radius = \ / 2.36 / 3.14 = 0.86 meters /
Hence the distance between the booms is 0.86 x2 = 1.72 meters
In this condition both aperture areas are tangents but it is better to overlap the areas a 10 % to prevent the generation of side lobes so that a distance of 1.55 meters between the antenna booms is recommended.
I hope this helps
73" de
i8CVS Domenico
----- Original Message ----- From: "Jean-François Ménard" [email protected] To: "i8cvs" [email protected] Sent: Saturday, August 08, 2009 4:00 PM Subject: Re: [amsat-bb] Antenna project with 2 ELK antennas
Hi,
I do not know much about antenna... But I tought that could be better for satellite this way... I did not do any search at this time about this project... it is only an idea that I had.
If you have any suggestion for such project using 2 Elk antenna.... please let me know.
I don't want to spend much money at this moment... and I have only these 2 antenna.
Wow !!
Thanks !! This is the kind of answer that I really like. I will try this with the recommendation you gave me. I'm not familiar with all those formulas regarding antenna, so a little help time to time is really helpful.... I like to learn, so you won't repeat the same thing twice.
Thank again.
Best 73
J-F VA2SS
73
2009/8/8 i8cvs [email protected]:
----- Original Message ----- From: "Jean-François Ménard" [email protected] To: "AMSAT Mailing list" [email protected] Sent: Thursday, August 06, 2009 10:44 PM Subject: [amsat-bb] Antenna project with 2 ELK antennas
Hi,
I have 2 ELK antennas here, and I would like to do an experiment with these two antennas. I would like to stack side by side, one vertical, and one horizontal.
73
Jean-François Ménard VA2SS
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= AMSAT www.amsat.org / Member #37102 ARRL www.arrl.org =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Hi Jean, VA2SS
Staking 2 ELK antennas side by side,one vertical,and one horizontal what type of polarization you plan to get ?
73" de
i8CVS Domenico
-- Jean-François Ménard VA2SS
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= AMSAT www.amsat.org / Member #37102 ARRL www.arrl.org =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=