having just read all this thread i would like to point some things out things
1
if the antenna is shorter it should still work just as well for 11m when it comes to SWR as the manufacturer will have (or should have) adjusted the value of the components in the matching device to compensate ....any random length will ajust to 50 ohm/ low SWR with the correct components in the matching device
2
fitting a stainless steel 102-inch whip to gain length may not work as the original top section is encased in fiberglass so will have a velocity factor so will need to be shorter for the same effect so the antenna may still see the SS whip to be the same-ish length
3
a ground plane kit will not have any difference with the signal on a A99 or any other 1/2wave ..although there may be benefits with CMC and causing TVI etc some have reported a bandwidth change but a coax choke will be more cost-effective
A GP kit will benefit a 5/8 wave and is really needed to make full use of a 5/8 wave (unless its a balanced like a gain master would be the same as putting GP on a dipole)
4
which is the better length the new 22 feet (if its a thing) or the old 24 feet
i will say at the moment the 22 feet
some time ago i modeled a 5/8 wave with 4 no 1/4 wave radials for the 4meter band, i adjusted it for best low takeoff angel it ended up almost dead on 5/8th wave..at the last moment i decided to model it on the mast so I connected the mast and found that the gain went up a little,..that's good i think until i notice the gain was now in the sky, the pattern looks like when the antenna is way long like 3/4 wave or something
i readjusted the length until a get my low take-off angel back (never got it as good but close) and by memory, it ended up somewhere between 1/2 wave and 5/8th wave
so is the 24 feet Imax too long when mounted on a mast??? so would look forwards fo folk the model the Imax 22 and 24feet on and off a mast (at the same height)
I think for modeling the top section needs to be 102 inches to compensate for the velocity factor if the fiberglass-encased radiator..i am pretty sure the top section is an 1/4 wave as folk in the past have replaced the top section with mobile antennas with no SWR chang
1
if the antenna is shorter it should still work just as well for 11m when it comes to SWR as the manufacturer will have (or should have) adjusted the value of the components in the matching device to compensate ....any random length will ajust to 50 ohm/ low SWR with the correct components in the matching device
2
fitting a stainless steel 102-inch whip to gain length may not work as the original top section is encased in fiberglass so will have a velocity factor so will need to be shorter for the same effect so the antenna may still see the SS whip to be the same-ish length
3
a ground plane kit will not have any difference with the signal on a A99 or any other 1/2wave ..although there may be benefits with CMC and causing TVI etc some have reported a bandwidth change but a coax choke will be more cost-effective
A GP kit will benefit a 5/8 wave and is really needed to make full use of a 5/8 wave (unless its a balanced like a gain master would be the same as putting GP on a dipole)
4
which is the better length the new 22 feet (if its a thing) or the old 24 feet
i will say at the moment the 22 feet
some time ago i modeled a 5/8 wave with 4 no 1/4 wave radials for the 4meter band, i adjusted it for best low takeoff angel it ended up almost dead on 5/8th wave..at the last moment i decided to model it on the mast so I connected the mast and found that the gain went up a little,..that's good i think until i notice the gain was now in the sky, the pattern looks like when the antenna is way long like 3/4 wave or something
i readjusted the length until a get my low take-off angel back (never got it as good but close) and by memory, it ended up somewhere between 1/2 wave and 5/8th wave
so is the 24 feet Imax too long when mounted on a mast??? so would look forwards fo folk the model the Imax 22 and 24feet on and off a mast (at the same height)
I think for modeling the top section needs to be 102 inches to compensate for the velocity factor if the fiberglass-encased radiator..i am pretty sure the top section is an 1/4 wave as folk in the past have replaced the top section with mobile antennas with no SWR chang
