Hey Now,
I have been experimenting with a 1/4 ground-plane w/ 4 drooping radials. After three attempts I am puzzled as how to achieve a reasonably flat VSWR across the frequencies I frequent (~ 11 - 10 meter). I'm trying to perfect it in anticipation of a skip-full dog day nights of summer. I prefer to work bare-foot or QRP so SWR is critical in making efficient use of my rig's RF output.
Question one
What length should I cut the radiator (driven element) for lowest SWR at a frequency of, let's say, 27.375 MHz. Using the 234/F(MHz) formula yields 102.6 inches. This produces a SWR ranging from 2.5 ~ 3. The Antenna resonates a 25.650 MHz with an SWR of 1.1 : 1. Moreover, I have always thought the 1/4 wave length of the 11 meter band was 108 inches, i.e on a cars 102 inch whip is attached to a 6 inch coil base. Please help, if you can, to clarify this to me - I am clearly missing something.
Question Two
I know that running the radials of the aforementioned Drooping 1/4 GP will lower the feed-point impedance from about 36 ohms (horizontal) to approximately 50 ohms at a droop angle of about 45 degrees from horizontal. I am using pretty good coax (RG-8/U - solid center, 95% braid). Does this antenna/transmission line set-up seem reasonably sound to you?
Also, I have heard conflicting "facts" within ARRL books and other sources regarding the length of the 1/4 GP drooping radials. Some say to cut the length 5% greater than that of the length of the radial (driven} at operating frequency and some sources say that this is merely a myth.
Thanks, in advance, for any light you may shed my way.
I have been experimenting with a 1/4 ground-plane w/ 4 drooping radials. After three attempts I am puzzled as how to achieve a reasonably flat VSWR across the frequencies I frequent (~ 11 - 10 meter). I'm trying to perfect it in anticipation of a skip-full dog day nights of summer. I prefer to work bare-foot or QRP so SWR is critical in making efficient use of my rig's RF output.
Question one
What length should I cut the radiator (driven element) for lowest SWR at a frequency of, let's say, 27.375 MHz. Using the 234/F(MHz) formula yields 102.6 inches. This produces a SWR ranging from 2.5 ~ 3. The Antenna resonates a 25.650 MHz with an SWR of 1.1 : 1. Moreover, I have always thought the 1/4 wave length of the 11 meter band was 108 inches, i.e on a cars 102 inch whip is attached to a 6 inch coil base. Please help, if you can, to clarify this to me - I am clearly missing something.
Question Two
I know that running the radials of the aforementioned Drooping 1/4 GP will lower the feed-point impedance from about 36 ohms (horizontal) to approximately 50 ohms at a droop angle of about 45 degrees from horizontal. I am using pretty good coax (RG-8/U - solid center, 95% braid). Does this antenna/transmission line set-up seem reasonably sound to you?
Also, I have heard conflicting "facts" within ARRL books and other sources regarding the length of the 1/4 GP drooping radials. Some say to cut the length 5% greater than that of the length of the radial (driven} at operating frequency and some sources say that this is merely a myth.
Thanks, in advance, for any light you may shed my way.