Antenna placement question?

[WSEZ903]

I have a Subaru Forester Sport that I have a Tram 5.5" mag mount with a Browning UHF gain antenna that I have cut to 467 MHz.  I have purchased direct mount to the roof but I want to drill once and be done.  Question is when I place the mag mount in the middle in front of the shark fin by a few inches I get an SWR of 1.7 of higher.  If I move it in between the shark fin and the side rails on passenger side it drops to 1.5 +/-.  If I move it to the same spot on divers side I get about 1.3 +/-.  The back of the vehicle does have a fiberglass/plastic cowling for rear window and more towards the front I have the "Moon Roof" as they call it.  I do have a roof rack that I put on once in a while and with it on or off I did not notice any gain or loss in SWR when testing with it on the sides.  The roof rack rail in attached picture in the back I have moved forward and all the way back and it did not really affect the reading.  I.e. 1.52 vs 1.56.

Any thoughts as to why it is lower on the drivers side vs center?  Attached is a screen shot of my roof.  Side note the passenger side black rectangle that looks like it is on roof rack it the thumb screw for 360 camera mount.

Edited November 22 by WSEZ903
Mis spelled word.

[WRYZ926]

Double check to see what the SWR is currently on 467.550 and 467.725 before you make any adjustments. It's always easier to make the antenna shorter verses trying to lengthen it after cutting.

[WSEZ903]

2.10 on 550 and 2.20 on 725

 

i put the midland mxta26 on and it is at 1.10 (550) and 1.7-1.9 (725) Ironically it was a lot higher with mag mount so I went with the Browning BR-450 instead as I had installed them in the past on vehicles and no issues.
 

I have it (browning ) cut to 470, now thinking I don’t know why and it might be a tad too short.   I will see if I can find where I can but a new bottom rod or just order a new antenna and deal with the loss.  I have the midland in there for now. Midland is ok, but browning seems to have a better signal to me. 

[WSEZ903]

OK  so I had added a reply twice since my last but it did not post for what ever reason.  

I actually cut the antenna to 470 for what ever reason.  I honestly do not know what I was thinking.  So I ordered a new one and cut it to the 465 are.  Did a test and SWR was 1.80-85 area.  Took about 3 mil off and now 2.2.  I guess i need it  longer or I am not measuring the correct spot when cutting?  I also have the midland gain antenna that I get a bit of a better reading on but it does not pick up as well.  So, I took the original Browning BR-450 antenna and put it back on for the time being as it is below 2.0. 

Thanks for all the help in this. It is really appreciated.

[SteveShannon]

7 hours ago, WSEZ903 said:

OK  so I had added a reply twice since my last but it did not post for what ever reason.  

I actually cut the antenna to 470 for what ever reason.  I honestly do not know what I was thinking.  So I ordered a new one and cut it to the 465 are.  Did a test and SWR was 1.80-85 area.  Took about 3 mil off and now 2.2.  I guess i need it  longer or I am not measuring the correct spot when cutting?  I also have the midland gain antenna that I get a bit of a better reading on but it does not pick up as well.  So, I took the original Browning BR-450 antenna and put it back on for the time being as it is below 2.0. 

Thanks for all the help in this. It is really appreciated.

Is the Browning a higher Q antenna?   How wide is the dip? You’ve been aiming at 465.xxx MHz. How is it at 467.xxx MHz?  Do you have someone you could borrow an antenna analyzer from?  A cheap NanoVNA will sweep the SWR so you can see what the response is across a range of frequencies. It could save you the expense of going through antennas. 
Is it just a piece of stainless steel whip you need to replace the one you trimmed? Sometimes auto parts stores have replacement whips.

[WSEZ903]

I will ask around.  It is the browning BR-450 https://a.co/d/0DDe9XK. Amazon link. 
 

this is with the original one I had purchased that I put back on. 462 is fine. 467 is a bit higher.pictures attached. 
 

I will check an auto parts store for other whips. Home Depot was going to be my guess.   My goal is to get the 467 side to 1.25 or better.  Just figured it would help prolong the life of the radio.