Imax above beam

[fisjr]

I have a 32 foot tower with maco a y-quad on it, My question is can i add my imax to the top of the mast for the beam. will it interfere being in between the vert. top eliments?

 

[wavrider]

With the type of yagi a Y quad is the mast pipe and Imax 2000 would skew the radiation pattern of the yagi, also may have effect on the VSWR.

If it was a yagi horizontal polarized with the typical 1/2 wl radiators then it would work fine placed above that.

 

[Needle Bender]

you wuill probably see more effect on the imax then the yquad. the imax will have more strength in the forwrd bean direction and a little less to the back. the yquad is looking for a resonent 1/4 wave above the boom not a 5/8. it will have an effect on the vertical beam but nothing to worrry about and almost nothing on horiz

 

[wavrider]

you wuill probably see more effect on the imax then the yquad. the imax will have more strength in the forwrd bean direction and a little less to the back. the yquad is looking for a resonent 1/4 wave above the boom not a 5/8. it will have an effect on the vertical beam but nothing to worrry about and almost nothing on horiz

So you do not think there would be any mutual coupling between the IMAX 2000 mast and the fact that the driven element of the Y quad is only a 36" from the mast of the IMAX2000?

 

[Needle Bender]

yes maybe a little but how many inches away from the driven elemnent is the rotor or mounting pole and coax shield? does that ruin the pattern with mutual coupling??

 

[wavrider]

That is a good Question and yes it does to an extent.

The moonraker 4 was a prime example of the tower effecting the performance.

The instructions say to install the vertical gamma match in the bottom element, just inches away from the tower or mast pipe.

If the gamma is flipped 180 degrees and installed on the upper vertical element, then waterproofed the yagi seemed to have better rejection. Sort of like a JO Gunn configuration. Maybe their rejection claims is not all that much of advertising hype, no tower to degrade the performance of the vertical element of the yagi.

So with the tower on the bottom of the vertical driven element, and the mast pipe on the top of the boom it is a no win situation for a vertical yagi.

Will it work? Yes but with what efficiency?

If an OP goes through all the work to install a tower, the expense of rotor and yagi, why gamble on installing a ground plane in the middle of the vertical radiating elements when it can do nothing but degrade the performance of the either antenna?

 

[Needle Bender]

who knows, maybe it will add gain to the vertical with all that antenna there throwing more signal to the front

 

[wavrider]

who knows, maybe it will add gain to the vertical with all that antenna there throwing more signal to the front

Hmm maybe you have something there. I do know from experience that having a big yagi under a groundplane does help the performance of the ground plane.

 

[fisjr]

I think i will put the 2000 in the rear of the house, just can't get any real height. Thanks to everyone.

 

[Needle Bender]

id put it up on the beam mast and if there was a problem then move it. if your like most operators youl be using the omni 5 times more often then the beam

 

[wavrider]

op:

 

[148 Alaska]

I have mine above my TH-6DXX...works fine....

 

[Needle Bender]

I have mine above my TH-6DXX...works fine....

are you the 148 out of alaska that we hear on L38 who sounds so much like 625 jack?

 

[Mudfoot]

Put it up and see what it does. If it works, then leave it up. If it dont, then take it down.

It's just an antenna. Were not physicists.

 

[Needle Bender]

i think the nature of a beam is that the elements are looking for each other to work right and thats why you can use a pole or rotor up the middle and it still works right. the imax isnt the right length to activate like the 1/4 wave element halves and so it might not even make a difference or it might F#C% it all up!