You want to run legal limit mobile, better signal reports, run multiple bands off one antenna, than run a bugcatcher !
Its really simple, so please follow along
I originally built mine in march of 1996 its 8”x8”, hopefully this will give you an idea of what we are discussing
I started off HF mobile with the ham sticks & found I was 33-55 rst at best
Upgraded to a hustler multi resonant-er system & my signals increased 55-57
The commercial bugcather I purchased changed that to 55-59 all the time
So after my purchase I thought I can build that, & mine outperformed the commercial one so bye bye it went
There is no wrong or right way to build one
My friend AA1ME built one using copper screw on connectors for his base & top of coil
Its only limited by your imagination & building skills
Any one can really build one if they set their mind to it
Go large or go home
If you make a coil square do not have sharp corners as thats not good in coil theory
Purists in the hobby will tell you that mine is incorrect & I know it that it is, my capacitance hat really needs to be at least 6" above the coil
I am now helping Steve K1GMM design a coil for 40M, so all info is based upon this band for the remainder of the discussion here
I used this site for its coil calculator ~ http://hamwaves.com/antennas/inductance.html just plug in your figures and away you go
This will help you determine the size & inductance needed for your application
Decide what wire diameter you will use, heres a handy chart to reference
Here we decided to go with a 6" coil that is 8" long using 12gauge wire
this gives us 85 microhenrys of inductance & a self resonating freq of 7.2Mhz
I would also make the overall length a bit longer to compensate for the windings, better to have some excess
so here is my design plan based around this info
Remember a square coil is more efficient, however due to space limitations etc we cant have such all the time
Larger diameter wire has more skin effect which translates in more DB's
Please keep the bottom of the coil at least 6" above the roof line of your vehicle
A longer whip on top of the coil will hear better than a shorter whip
We can talk about capacitance hats later if need be
So go build one & enjoy the HF bands while mobile
73 AA1PR
