Hi,

I 'd like to know what is the opening of the Degen BBQ main lobe (2-element
HF quad).
Even the manufacturer website doesn't provide this info, only the gain, 11
dBi.

Maybe something like 30° wide ? Can someone confirm ?

Thanks in advance

73
Thierry, ON4SKY
http://www.astrosurf.com/lombry

Hi Thierry,

Thank you for pointing this out, I'll post some plots in the next couple of
days.

You will find that, if you download the TCA article it does show some plots.

While we are proud of the 11dBi gain, it must be correctly reference to a
dipole and the gain is about 4dBd (depending on the band). This is mainly
do to the reason that we compare our modelled antenna with the modelled
Dipole (on the same software) to give fair value. This ensure any form of
errors in gain are cancelled out correctly instead of using the typical
2.1dbi value for a Dipole and providing a falsely unrealistic value.

I'll also send you a copy of the charts for your records.

73,
Guenther VE3CVS

www.degendesigns.com


Hi,

I 'd like to know what is the opening of the Degen BBQ main lobe
(2-element
HF quad).
Even the manufacturer website doesn't provide this info, only the gain, 11
dBi.

Maybe something like 30° wide ? Can someone confirm ?

Thanks in advance

73
Thierry, ON4SKY
http://www.astrosurf.com/lombry

Guenther, VE3CVS wrote:
"This ensure any form of errors in gain are cancelled out correctly
instead of using the typical 2.1 dbi value for a Dipole and providing a
falsely unrealistic value."

Gain is always measured with respect to some reference antenna. The
isotropic is a hypothetical antenna so the usual practice is to use a
1/2-wavelength reference antenna. Gain is a power ratio which is equal
to the voltage ratio squared. When dBd or some other reference is not
specified, dBi is presumed.

Kraus says the 1/2-wavelength resonant antenna`s gain over the isotropic
is 1.64. This appears on page 454 of the 1950 edition of "Antennas".
Terman was Kraus` consulting editor.

Terman says the same as Kraus on page 871 of the 1955 edition of
"Electronic and Radio Engineering". Directive gain ignores losses.
"Power Gain" as wsed to determine effective radiated power takes into
account loss in the antenna used. The reference antenna is considered
lossless.

The dB gain figure calculated from a 1.64 power ratio is shown on page
2-12 of the 19th edition of the ARRL Antenna Book. Gain in the
1/2-wavelength dipole`s best direction is shown as 2.14 dBi.

0 dBd is identical to 2.14 dBi. No false or unrealistic values obtain
from using either reference.

Best regards, Richard Harrison, KB5WZI

Hi Richard,

I have no argument with your statement and I believe the value of 2.14dbi
gain for a dipole (determined by people far more knowledgeable than I in
these matters)

However, you will find that modelling software sometimes does some weird and
wonderful things.

Depending on the modelling software used (and how it used), the 1/2 wave
dipole mentioned can modelled with a gain of approx. 4 to 7dBi. So one
could falsely assume that a dipole has a gain of (lets use the average of
6dBi minus 2.14 dBi) of 3.86dBd. Which I agree is incorrect.

The point I was trying to make, was that to correct for this minor variation
in modelling characteristics, compare the dipole optimized for the same
frequency with that of the antenna designed with both numbers calculated dBi
and then manually calculate the difference to achieve realistic dBd value.

While I would love higher gain values compared to a dipole, I feel that to
fairly represent what we are doing, we should be honest in our comparison by
comparing items on the same playing field, which is why we provide our gain
values in both dBi and dBd using the above method.

Now before anyone takes offence that I am blaming software. No, I'm not. I
couldn't live without them as they save thousands of hours in development.

Hopefully, this clears up my earlier statement.

Best Regards,
Guenther VE3CVS

www.degendesigns.com

"always willing to learn and hopefully never to dumb to stop learning"



"Richard Harrison" wrote in message
...
Guenther, VE3CVS wrote:
"This ensure any form of errors in gain are cancelled out correctly
instead of using the typical 2.1 dbi value for a Dipole and providing a
falsely unrealistic value."

Gain is always measured with respect to some reference antenna. The
isotropic is a hypothetical antenna so the usual practice is to use a
1/2-wavelength reference antenna. Gain is a power ratio which is equal
to the voltage ratio squared. When dBd or some other reference is not
specified, dBi is presumed.

Kraus says the 1/2-wavelength resonant antenna`s gain over the isotropic
is 1.64. This appears on page 454 of the 1950 edition of "Antennas".
Terman was Kraus` consulting editor.

Terman says the same as Kraus on page 871 of the 1955 edition of
"Electronic and Radio Engineering". Directive gain ignores losses.
"Power Gain" as wsed to determine effective radiated power takes into
account loss in the antenna used. The reference antenna is considered
lossless.

The dB gain figure calculated from a 1.64 power ratio is shown on page
2-12 of the 19th edition of the ARRL Antenna Book. Gain in the
1/2-wavelength dipole`s best direction is shown as 2.14 dBi.

0 dBd is identical to 2.14 dBi. No false or unrealistic values obtain
from using either reference.

Best regards, Richard Harrison, KB5WZI

Guenther, VE3CVS wrote:
"I feel that to fairly represent what we are doing, we should be honest
in our comparison by comparing items on the same playing field, which
is why we provide our gain values in both dBi and dBd using the above
method."

That should be beyond impeccable. It is almost fool proof if free-space
conditions are specified or if the incremental placement gain is
itemized for a fair comparison.

In measuring gain you can place the reference dipole in the same
location or at the same height at a similsr location to that of the
device under test. When I`ve done that it was satisfying to get test
results which met expectations. It proved performance of the new
antennas.

Best regards, Richard Harrison, KB5WZI