Hi Gus, 8P6SM
Mounting 3 turn helix antenna for 2400 MHz concentrically inside a 3 turns helix antenna for 1268 MHz was used as a feed both wounded LHCP to illuminate a ground station prime focus dish for RHCP uplink and downlink on Mode-L/S for AO40 and it worked very well.
If you plan to build a 10 turns RHCP helix antenna for 70 cm conentrically into a 5 or 6 turns RHCP helix antenna for 2 meters in my opinion it should work as well but the weight of this antenna will be very very hight and not practical to be used in comparison with yagi antennas.
73" de
i8CVS Domenico
----- Original Message ----- From: "Gus" gus@8p6sm.net To: AMSAT-BB@amsat.org Sent: Wednesday, March 12, 2014 9:33 AM Subject: [amsat-bb] Question for the antenna gurus
Regarding axial-mode helix antennas, what happens if you build a helix for each of two different bands (like 2M/70cm), and mount them concentrically, on the same backplane? -- Gus 8P6SM The Easternmost Isle _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb