Lower SWR with 102 than 108

[Captain Chaos]

I am getting a lower SWR with SS 102" whip (aprox. 1.3:1) than 108" (1.6:1) on 27.205
I'm using HD stud mirrot mount on my semi. If I go down to 25.405 I get 1.2:1 with the SS 108" whip. Should I roll with the 108 or put the 102 back on?
Sorry in advance for the newb question.

 

[undertaker]

102 ………...

 

[Captain Chaos]

102 ………...

What I don't understand then I thought 108 was what I should be running for 11m I thought 102 was too short without a spring.

 

[2NC995]

102 always worked for me.

 

[Captain Chaos]

102 always worked for me.

102 with a 6inch spring or 102 with no spring

 

[2NC995]

No spring. However, I did have a fairly tall mount.

I would go with whatever tunes better for your application. If the 102” is it, then you’re good.

Aside from off-road vehicles or applications where the antenna needs to be tied down, I don’t like springs...especially on a 9’ long wet noodle.

 

[oldtymer]

What I don't understand then I thought 108 was what I should be running for 11m I thought 102 was too short without a spring.

The higher you are in frequency the shorter the antenna -if you check 25.405 with the 102" it will be higher than the 108" because it is shorter.

 

[Captain Chaos]

The higher you are in frequency the shorter the antenna -if you check 25.405 with the 102" it will be higher than the 108" because it is shorter.

So I should run the 102 for cb instead of the 108?

 

[2NC995]

Either run the 102” or start trimming the 108 until the SWR is where you want it.

 

[357magnum]

If the 102" works & you don't have a problem w/out the spring .... leave it alone . Just my 2 cents . 73 & God Bless , Leo BTW Welcome to the forum !

 

[2NC995]

I’m not sure how folks come up with 108”, to be honest. I never remember hearing this in years past, but it seems like everyone talks about 108” now.

Here’s a 1/4 wave calculator for you to play with. Assuming .956 as a generic velocity factor for stainless, I come up with 103.76”. Your 102” whip, plus your mounting stud, is probably very close to that. Sounds like you could be a hair longer, but definitely not six inches.

https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/

 

[Captain Chaos]

I’m not sure how folks come up with 108”, to be honest. I never remember hearing this in years past, but it seems like everyone talks about 108” now.

Here’s a 1/4 wave calculator for you to play with. Assuming .956 as a generic velocity factor for stainless, I come up with 103.76”. Your 102” whip, plus your mounting stud, is probably very close to that. Sounds like you could be a hair longer, but definitely not six inches.

https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/

Thanks for that info

 

[2NC995]

Thanks for that info

Well, there’s a good chance someone smarter will come along with more info, but in my opinion you’re not going to go wrong running the antenna with the lower SWR.

 

[Woody-202]

I've never been very picky when it came to mobile SWR as long as it was under 2:1 which ever SWR you don't want (1.3 or 1.6) send it to me. I'll take it.

 

[2NC995]

I've never been very picky when it came to mobile SWR as long as it was under 2:1 which ever SWR you don't want (1.3 or 1.6) send it to me. I'll take it.

Lol, You mean don’t chase those last few hundredths of a watt?