Anyone have any idea as to the probable performance characteristics of two
whip 40" whip antennas mounted approx. six inches apart, and used for
receiving shortwave, primarily between 6 MHz and 12 MHz? Would they be more
receptive to a signal approaching f/b, as opposed to s/s? Just wondering...
Hoping someone can offer some advice as to whether they would be in any way
directional.

Thanks for any replies,

Dave

Dave wrote:
Anyone have any idea as to the probable performance characteristics of two
whip 40" whip antennas mounted approx. six inches apart, and used for
receiving shortwave, primarily between 6 MHz and 12 MHz? Would they be more
receptive to a signal approaching f/b, as opposed to s/s? Just wondering...
Hoping someone can offer some advice as to whether they would be in any way
directional.

They would be directional at the frequency where
6 inches is 1/8 wavelength. :-)
--
73, Cecil http://www.w5dxp.com

"Cecil Moore" wrote in message
news
Dave wrote:
Anyone have any idea as to the probable performance characteristics of
two whip 40" whip antennas mounted approx. six inches apart, and used for
receiving shortwave, primarily between 6 MHz and 12 MHz? Would they be
more receptive to a signal approaching f/b, as opposed to s/s? Just
wondering... Hoping someone can offer some advice as to whether they
would be in any way directional.

They would be directional at the frequency where
6 inches is 1/8 wavelength. :-)
--
73, Cecil http://www.w5dxp.com

Hey Cecil, thanks for the reply.

Hmm. So, correct me if I'm wrong, but from what you're saying they would
actually have some directional characteristics at approx. 2.5 MHz. What if
I angled them apart at, say, 45 degrees? That would, I think, put the tops
about 57 inches apart, and the two whips at right angles to each other. Any
ideas what that would do? Or, if I flattened them out in opposite
directions? I need an ARRL Antenna Handbook, only I wouldn't know what to
look up...

Do appreciate your reply. Gives me something to think about...

Dave

"Dave" wrote in message
...

"Cecil Moore" wrote in message
news
Dave wrote:
Anyone have any idea as to the probable performance characteristics of
two whip 40" whip antennas mounted approx. six inches apart, and used
for receiving shortwave, primarily between 6 MHz and 12 MHz? Would they
be more receptive to a signal approaching f/b, as opposed to s/s? Just
wondering... Hoping someone can offer some advice as to whether they
would be in any way directional.

They would be directional at the frequency where
6 inches is 1/8 wavelength. :-)
--
73, Cecil http://www.w5dxp.com

Hey Cecil, thanks for the reply.

Hmm. So, correct me if I'm wrong, but from what you're saying they would
actually have some directional characteristics at approx. 2.5 MHz.

I don't get that number at all. Splitting the difference between 6 and 12
Mhz, say
9 Mhz, an 1/8th wavelength distance would be about 4 meters.
Anybody have a url of a page that shows receive pattern of two antennas at
different
spacings, 1/8, 1/4, 3/8, 1/2 wavelengths?
Dave, I recommend you download the demo version of EZNEC, it won't take
to long to model a couple of verticals at different spacing.
Mike

amdx wrote:
I don't get that number at all.

Yep, Dave was off by a couple of magnitudes.
6 inches is 1/8WL at 246 MHz.

Anybody have a url of a page that shows receive pattern of two antennas at
different spacings, 1/8, 1/4, 3/8, 1/2 wavelengths?

My 1980's ARRL Antenna Book has those patterns
using different phasings and different spacings.
--
73, Cecil http://www.w5dxp.com

"Cecil Moore" wrote in message
. net...
amdx wrote:
I don't get that number at all.

Yep, Dave was off by a couple of magnitudes.
6 inches is 1/8WL at 246 MHz.

Anybody have a url of a page that shows receive pattern of two antennas
at different spacings, 1/8, 1/4, 3/8, 1/2 wavelengths?

My 1980's ARRL Antenna Book has those patterns
using different phasings and different spacings.
--
73, Cecil http://www.w5dxp.com

Dave doesn't have the book, still looking for a url.
Mike

Dave wrote:
"Cecil Moore" wrote in message
They would be directional at the frequency where
6 inches is 1/8 wavelength. :-)
--
Hmm. So, correct me if I'm wrong, but from what you're saying they would
actually have some directional characteristics at approx. 2.5 MHz.

Make that 250 MHz. If 6 inches is 1/8WL, then one
wavelength would be 4 feet. 984/4 = 250 MHz.
--
73, Cecil http://www.w5dxp.com

"Dave" wrote in
:

Anyone have any idea as to the probable performance characteristics of
two whip 40" whip antennas mounted approx. six inches apart, and used
for receiving shortwave, primarily between 6 MHz and 12 MHz? Would
they be more receptive to a signal approaching f/b, as opposed to s/s?
Just wondering... Hoping someone can offer some advice as to whether
they would be in any way directional.

If they are simply in parallel, they would not have much directivity. But
if one were to be phase-inverted with respect the other, there would be a
strong null along the bisector of the line joining them.

The gain at 9mhz is on the order of -30dbi, though so you will need a good
receiver or even a preamp.


--
Dave Oldridge+
ICQ 1800667

"Dave Oldridge" wrote in message
9...
"Dave" wrote in
:

Anyone have any idea as to the probable performance characteristics of
two whip 40" whip antennas mounted approx. six inches apart, and used
for receiving shortwave, primarily between 6 MHz and 12 MHz? Would
they be more receptive to a signal approaching f/b, as opposed to s/s?
Just wondering... Hoping someone can offer some advice as to whether
they would be in any way directional.

If they are simply in parallel, they would not have much directivity. But
if one were to be phase-inverted with respect the other, there would be a
strong null along the bisector of the line joining them.

The gain at 9mhz is on the order of -30dbi, though so you will need a good
receiver or even a preamp.


--
Dave Oldridge+
ICQ 1800667

Aha! A strong (or deep) null! That's actually what I'm looking for. So,
what would I look up to start learning how to set one up as phase-inverted?
I have a copy of Joe Carr's Antenna Handbook (think that's the title), would
it have anything on such a setup, do you think? What would I look for in
the ARRL Antenna Handbook? Does this type of setup have a name to search on?

And yes, compared to my 110' longwire, the signal is miniscule. But I'm
working on that.

Thank you so much, Dave, for this input. Now I have some idea as to what I
am looking for, (I *think*).

Much appreciated.

Dave Beane

Trying to phase two antennas that close together at that frequency range
will be an educational experience at best, but more likely just an
exercise in frustration unless you have much more patience than average.
Such an array will be hyper-sensitive to everything. You might be able
to fleetingly see a null after a lot of tweaking, but I seriously doubt
you'll even get that. A tiny change in frequency, wiggling of the whips,
or even movement in the vicinity of the whips will have a profound
effect on any null you might see.

If a null from a small antenna is what you want, you'd have much better
luck with a carefully constructed and balanced ("shielded") loop.

Roy Lewallen, W7EL