On Tue, 13 Sep 2005 20:43:23 -0700, Roy Lewallen
wrote:

An antenna doesn't have a single "radiation angle". It radiates at all
angles. The relevant question is how much does it radiate at the
particular angle of interest, not at which angle does it radiate the
most. An antenna which radiates its maximum at a high angle might well
radiate more at a low angle than an antenna with a lower angle of
maximum radiation.

Roy Lewallen, W7EL

Hello Roy,

I do understand that. I also understand when you say radiation angle
your talking about the primary or dominent lobe(s). There may be
many other lobes at useful or less than useful angles present as well.

However, how does that relate to using a shortend antenna with maybe
10% radiation efficientcy to a dipole at a reasonably attainable
height?

Allison
KB1GMX


wrote:
On 13 Sep 2005 16:15:08 GMT, "Bill Turner" wrote:

Without more information, this comparison is flawed. A mobile whip has
a lower angle of radiation than a horizontal dipole. . .

Correct on radiation angle . . .

However, how does that relate to using a shortend antenna with maybe
10% radiation efficientcy to a dipole at a reasonably attainable
height?

Well....Exactly as he described.
An antenna which radiates its maximum at a high angle might well
radiate more at a low angle than an antenna with a lower angle of
maximum radiation.

The thing is "might".... My mobile antenna on 40m is *much* less
efficient than my dipole at 40 ft. But...It still is the best to longer
hauls over about 800 miles, and to dx. In it's case, it does radiate
more at the lower angles I'm using at that time, vs the dipole.
With some lesser mobiles, "mine is fairly stout", this might not be
the case. The best antenna should always be decided to fit the
usual paths to be used. In the case of my mobile vs the dipole, it's
possible that if the dipole were raised another 1/4 wave higher, it
could match the mobile at those lower angles.
At home, I often ran a dipole at 40 ft vs a full size ground plane at
the same height. Both were pretty efficient. Efficiency comparisons
were fairly useless as to actual performance. What really decides
which is best at a given time, is the path, and angles to be used.
Now, if you compare two same length low dipoles, both to NVIS, both
shooting straight up, and one is less lossy than the other as far as
feeding method, etc, then yes, efficiency will decide which one is
best.
MK

wrote:
On Tue, 13 Sep 2005 20:43:23 -0700, Roy Lewallen
wrote:


An antenna doesn't have a single "radiation angle". It radiates at all
angles. The relevant question is how much does it radiate at the
particular angle of interest, not at which angle does it radiate the
most. An antenna which radiates its maximum at a high angle might well
radiate more at a low angle than an antenna with a lower angle of
maximum radiation.

Roy Lewallen, W7EL


Hello Roy,

I do understand that. I also understand when you say radiation angle
your talking about the primary or dominent lobe(s). There may be
many other lobes at useful or less than useful angles present as well.

However, how does that relate to using a shortend antenna with maybe
10% radiation efficientcy to a dipole at a reasonably attainable
height?

Allison
KB1GMX

The context was that one antenna was better for DX than the other
because it had a "lower radiation angle". An antenna with a "low
radiation angle" which is 10% efficient probably radiates less at low
angles than a more efficient antenna with a "high radiation angle".
Therefore it's not a better DX antenna. My point is simply that the
angle of maximum radiation is not a valid criterion for comparing antennas.

Roy Lewallen, W7EL