[Antennas] How to make an Air Coil (AKA Loaded Whip) 315MHz antenna

Wed Apr 18 12:13:55 EDT 2018

"Optimum Design of Short Coil-Loaded High-Frequency Mobile Antennas"
(Brown, W6TWW) appears in _The ARRL Antenna Compendium Volume 1_. It
answers many, if not all, of my questions about how to make an loaded
coil 315MHz antenna similar to the antenna show at this website:

http://www.byvac.com/downloads/RLnn/How-to-make-a-Air-Cooled-433MHz-antenna.pdf
 If you click on the link you can see an image of the 433MHz antenna.
Note how the ratio of the coil's diameter to its length is half or less.
 Meanwhile, the ARRL article suggests that the exact opposite works
better. My reading of the following excerpt leaves me with the 
impression that the coil's diameter ought to be twice as large as its
length:
 High Q can be obtained by going to large-diameter coils
 having a diameter-to-length ratio of two, by using larger
 diameter wire, by using more spacing between turns, and by
 using low-loss polystyrene supporting and enclosure materials.
 An anecdotal survey of the coils used to tune my short whip for ham
bands reveals a larger diameter, which works its way up to twice as
large for the lowest bands. For a given Q, is the coil's diameter 
inversely proportional to the frequency? In other words, for a given Q,
does the coil's diameter monotonically decrease with frequency?
Thank you in advance.
73,
-- 
Don Kuenz, KB7RPU
Genius is nothing but a greater aptitude for patience. - de Buffon