Probably a stupid question, but...
 

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

Probably a stupid question, but...
 

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

Probably a stupid question, but...
 

"Cecil Moore" wrote in message
...
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

Probably a stupid question, but...
 

"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

Probably a stupid question, but...
 

"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

Probably a stupid question, but...
 

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

Probably a stupid question, but...
 

"Roy Lewallen" wrote in message
...
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

Found my copy of Joe Carr's Practical Antenna Handbook, and re-read the
section on phasing verticle antennas. I believe you. Back to square one,
which was the thought that a loop was probably my best bet (I had come to
that conclusion a while back, but forgot why.)

Did try a shielded loop once upon a time, but didn't feel it gave me
anything to look forward to. Guess I'll dig it out and try it again. Will
try shielding it with copper "tape" and see what that buys me. I did try a
piece of coax wound in a triple-turn loop to give me 2.5 or 3 uH with which
to tune, with the shield cut away to expose the center conductor for a
couple inches, but didn't feel this offered anything either. Not sure what
I'll do. Poke around and try different things until I find something that
works better than the rest. Any ideas? I'm all ears. I tried the whips
because I had them on hand, and they were easy to install. Seems I read
somewhere that contrary to conventional wisdom, the shield on a shielded
loop doesn't actually shield at all, but becomes the antenna element.
Anyone know anything about that line of thought? I obviously know nothing,
and am trying to learn. Just don't know where to focus my energies.

Thanks,

Dave

Probably a stupid question, but...
 

Dave wrote:
. . .
. . .Seems I read
somewhere that contrary to conventional wisdom, the shield on a shielded
loop doesn't actually shield at all, but becomes the antenna element.
Anyone know anything about that line of thought? I obviously know nothing,
and am trying to learn. Just don't know where to focus my energies.

That's been discussed on this newsgroup a number of times. You should be
able to find the relevant threads via groups.google.com.

Yes, the "shield" doesn't shield the antenna -- in fact, the outside of
the "shield" *is* the antenna. What it does is aid in balancing the
antenna, reducing common mode pickup which can reduce the null depth.
"Conventional wisdom" that holds otherwise isn't wisdom at all, but a
lack of understanding of some basic electromagnetic principles.

There's undoubtedly a massive amount of information easily available on
the web regarding building and using small loop antennas. All you have
to do is ignore the ubiquitous "conventional wisdom" explanations of how
a "shielded" loop operates.

Roy Lewallen, W7EL

Probably a stupid question, but...
 

"Dave" wrote in message
...

"Cecil Moore" wrote in message
...
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

Probably a stupid question, but...
 

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

Probably a stupid question, but...
 

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

Probably a stupid question, but...
 

"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

Probably a stupid question, but...
 

"Dave" wrote in
:


"Roy Lewallen" wrote in message
...
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

Found my copy of Joe Carr's Practical Antenna Handbook, and re-read
the section on phasing verticle antennas. I believe you. Back to
square one, which was the thought that a loop was probably my best bet
(I had come to that conclusion a while back, but forgot why.)

Did try a shielded loop once upon a time, but didn't feel it gave me
anything to look forward to. Guess I'll dig it out and try it again.
Will try shielding it with copper "tape" and see what that buys me. I
did try a piece of coax wound in a triple-turn loop to give me 2.5 or
3 uH with which to tune, with the shield cut away to expose the center
conductor for a couple inches, but didn't feel this offered anything
either. Not sure what I'll do. Poke around and try different things
until I find something that works better than the rest. Any ideas?
I'm all ears. I tried the whips because I had them on hand, and they
were easy to install. Seems I read somewhere that contrary to
conventional wisdom, the shield on a shielded loop doesn't actually
shield at all, but becomes the antenna element. Anyone know anything
about that line of thought? I obviously know nothing, and am trying
to learn. Just don't know where to focus my energies.

I made a perfecly workable little DF once on a ferrite rod, wound with a
few turns. Worked like gangbusters on the local 2 and 6mhz stuff that I
was trying to locate.



--
Dave Oldridge+
ICQ 1800667

Probably a stupid question, but...
 

On 20 Sep, 22:39, Roy Lewallen wrote:
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

Let me clarify some of the remarks made. A efficient antenna is when
the wire is
one wave length long and fed at its extremities. This can be
circumvented on a loop
by winding the 1WL wire on a non conductive hoolah loop both in a
clock wise and counterclockwise
in a overlapping method ( insulated magnet wire preffered )
such that the windings inductance balance to zero for a resistive
impedance
at the feed point The windings may have to be stretched some what to
balance outany stray capacitance added
or a broadcast type variable capacitor can be added if one is lazy.
The bandwidth is broad enough on most bands with a resistive impedance
of around 50 odd ohms.
If one deviates much from the desired frequencylength one will see a
resistive impedance
in the single digits so take care with the wave length measurements
This loop design based on Gaussian laws provides a broad bandwidth
with smaller physical size
compared to the standard magnetic loop design together with extra
gain. And yes one does not
need that expensive high voltage variable capacitor required for
movement around the band as required with presently known loop
designs.
By the way the element can be jumpered for use on other bands!
Have fun
Art KB9MZ
PS I have written a somewhat amaterish thesis on Gaussian antennas
for which I have applied for a patents, I am sure that a scan of past
posts on the subject will reveal the URL which I have not put in my
memory box.
Amateurs have not used this new design method as they are happy with
existing
arrays knowing that all is already known about antennas and all later
designs
must be fraudulent
Art KB9MZ....xg

Probably a stupid question, but...
 

"amdx" wrote in message
...

"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


I've got the book on order at the library. May not wait. Might just buy
it, to have it on hand and have the latest edition.

Dave

Probably a stupid question, but...
 

"art" wrote in message
ps.com...
On 20 Sep, 22:39, Roy Lewallen wrote:
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

Let me clarify some of the remarks made. A efficient antenna is when
the wire is
one wave length long and fed at its extremities. This can be
circumvented on a loop
by winding the 1WL wire on a non conductive hoolah loop both in a
clock wise and counterclockwise
in a overlapping method ( insulated magnet wire preffered )
such that the windings inductance balance to zero for a resistive
impedance
at the feed point The windings may have to be stretched some what to
balance outany stray capacitance added
or a broadcast type variable capacitor can be added if one is lazy.
The bandwidth is broad enough on most bands with a resistive impedance
of around 50 odd ohms.
If one deviates much from the desired frequencylength one will see a
resistive impedance
in the single digits so take care with the wave length measurements
This loop design based on Gaussian laws provides a broad bandwidth
with smaller physical size
compared to the standard magnetic loop design together with extra
gain. And yes one does not
need that expensive high voltage variable capacitor required for
movement around the band as required with presently known loop
designs.
By the way the element can be jumpered for use on other bands!
Have fun
Art KB9MZ
PS I have written a somewhat amaterish thesis on Gaussian antennas
for which I have applied for a patents, I am sure that a scan of past
posts on the subject will reveal the URL which I have not put in my
memory box.
Amateurs have not used this new design method as they are happy with
existing
arrays knowing that all is already known about antennas and all later
designs
must be fraudulent
Art KB9MZ....xg


Thanks, Art (and others). I'll do a few searches on Google, and see what I
can come up with.

Much appreciated.

Dave

Probably a stupid question, but...
 

On 20 Sep, 22:39, Roy Lewallen wrote:
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

If it was just for receiving I would make two antennas in coil fashion
as shown every where
on the net, connect them together with a half wave length coax and try
stretch them apart as much as room suplies and then roll the excess
phasing coax up. The cb's have the super scanner antenna that partialy
follows this principle using 1 wave length antennas with the
connecting coax folded and pushed inside the connecting aluminum
channel. Using a rolled antenna tesla style with them being physically
close together would be an interesting experiment. Look up in the net
home made radios for the station tuning method and also you might want
to choose different methods to connect them starting with a wire
connecting the two wound antennas at the top and feeding th bottom!
( that method by the way requires the two antennas to be wound
inopposite directions) I imagine you could get a null just like
turning an inside tv antenna because these stations in this
frequencyare high power as can be seen when a rogue station opens up
ontop of the station that you are listenning to and want to null out
of the picture.
Have fun
Art KB9MZ

Probably a stupid question, but...
 

"Dave" wrote in
:

....
were easy to install. Seems I read somewhere that contrary to
conventional wisdom, the shield on a shielded loop doesn't actually
shield at all, but becomes the antenna element. Anyone know anything
about that line of thought? I obviously know nothing, and am trying
to learn. Just don't know where to focus my energies.

I have written a simple explanation on the operation of the so called
'shielded loop' at http://www.vk1od.net/shieldedloop/index.htm .

You may find the article of interest.

If you read and understand the content of the article, you will see the
pitfalls in using tape to 'shield' a loop.

Owen

Probably a stupid question, but...
 

"Roy Lewallen" wrote in message
...
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

Quck question, Roy,

Would it matter if I "separated" the whips electrically with, say, 55 feet
of coax? (That's approx the length I get for RG-174 coax, which is
something like 1/8" in diameter, with a velocity vactor of .66 and working
with 9 MHz.) Just a thought, but I don't know whether it has any merit or
not. And I am thinking I could adjust that "length" with an RLC circuit
through which I sort of "tune" it. What say you? Is this line of thought
worth persuing? Or would wiggling he whips still throw everything off?

And I do seem to have a fair abount of patience with this sort of thing.
Been working on the current project for about 2 years, had it working on and
off, taking it apart occasionally to implement some new retrofit or
engineering change. I am on disability, and have nothing but time on my
hands.

Thanks for any feedback...

Dave

Probably a stupid question, but...
 

"Dave" wrote in message
...

"Roy Lewallen" wrote in message
...
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

Quck question, Roy,

Would it matter if I "separated" the whips electrically with, say, 55 feet
of coax? (That's approx the length I get for RG-174 coax, which is
something like 1/8" in diameter, with a velocity vactor of .66 and working
with 9 MHz.) Just a thought, but I don't know whether it has any merit or
not. And I am thinking I could adjust that "length" with an RLC circuit
through which I sort of "tune" it. What say you? Is this line of thought
worth persuing? Or would wiggling he whips still throw everything off?

And I do seem to have a fair abount of patience with this sort of thing.
Been working on the current project for about 2 years, had it working on
and off, taking it apart occasionally to implement some new retrofit or
engineering change. I am on disability, and have nothing but time on my
hands.

Thanks for any feedback...

Dave



Forgot to mention one thing. Don't know if I said this before or not, but
this is of course for receive only. No transmitting with such a cob job...

Thanks,

Dave

Probably a stupid question, but...
 

Dave wrote:

Quck question, Roy,

Would it matter if I "separated" the whips electrically with, say, 55 feet
of coax? (That's approx the length I get for RG-174 coax, which is
something like 1/8" in diameter, with a velocity vactor of .66 and working
with 9 MHz.) Just a thought, but I don't know whether it has any merit or
not. And I am thinking I could adjust that "length" with an RLC circuit
through which I sort of "tune" it. What say you? Is this line of thought
worth persuing? Or would wiggling he whips still throw everything off?

And I do seem to have a fair abount of patience with this sort of thing.
Been working on the current project for about 2 years, had it working on and
off, taking it apart occasionally to implement some new retrofit or
engineering change. I am on disability, and have nothing but time on my
hands.

Thanks for any feedback...

You can answer most of your questions by modeling it with EZNEC. The
free demo program available from http://eznec.com is perfectly adequate
for the job. After going through the "Test Drive" tutorial in the
manual, I suggest that you take a look at the d_Cardioid.ez example file
to see how you can model an array with an ideal feed system. What you
should do is model your array in a similar manner, with two perfect
current sources. With the sources equal in magnitude and 180 degrees out
of phase, you'll get a bidirectional pattern, and it won't be sensitive
to frequency or element spacing. But then see what happens when you
change the phase and/or magnitude of one of the sources just slightly,
to simulate what any real phasing network would do. What happens to the
pattern? Look at the feedpoint impedances at various frequencies, and
see if you can figure out how you'll make a network to deliver the
correctly phased currents into those impedances. Another thing you can
do is try phasing them for a unidirectional pattern by giving the
sources a relative phase angle of 180 degrees minus the electrical
spacing of the elements (which of course will be different at each
frequency). You can get a nice looking pattern, but you'll find it
extremely sensitive to frequency and element spacing.

EZNEC will give you the opportunity to turn some of that available time
into an educational experience. I guarantee you'll learn a lot in the
process. If you want to learn even more about phased arrays, see Chapter
8 of the _ARRL Antenna Book_. The phased array section was completely
rewritten and updated for the latest (21st) edition.

Roy Lewallen, W7EL

Probably a stupid question, but...
 

"Roy Lewallen" wrote in message
...
Dave wrote:

Quck question, Roy,

Would it matter if I "separated" the whips electrically with, say, 55
feet of coax? (That's approx the length I get for RG-174 coax, which is
something like 1/8" in diameter, with a velocity vactor of .66 and
working with 9 MHz.) Just a thought, but I don't know whether it has any
merit or not. And I am thinking I could adjust that "length" with an RLC
circuit through which I sort of "tune" it. What say you? Is this line
of thought worth persuing? Or would wiggling he whips still throw
everything off?

And I do seem to have a fair abount of patience with this sort of thing.
Been working on the current project for about 2 years, had it working on
and off, taking it apart occasionally to implement some new retrofit or
engineering change. I am on disability, and have nothing but time on my
hands.

Thanks for any feedback...

You can answer most of your questions by modeling it with EZNEC. The free
demo program available from http://eznec.com is perfectly adequate for the
job. After going through the "Test Drive" tutorial in the manual, I
suggest that you take a look at the d_Cardioid.ez example file to see how
you can model an array with an ideal feed system. What you should do is
model your array in a similar manner, with two perfect current sources.
With the sources equal in magnitude and 180 degrees out of phase, you'll
get a bidirectional pattern, and it won't be sensitive to frequency or
element spacing. But then see what happens when you change the phase
and/or magnitude of one of the sources just slightly, to simulate what any
real phasing network would do. What happens to the pattern? Look at the
feedpoint impedances at various frequencies, and see if you can figure out
how you'll make a network to deliver the correctly phased currents into
those impedances. Another thing you can do is try phasing them for a
unidirectional pattern by giving the sources a relative phase angle of 180
degrees minus the electrical spacing of the elements (which of course will
be different at each frequency). You can get a nice looking pattern, but
you'll find it extremely sensitive to frequency and element spacing.

EZNEC will give you the opportunity to turn some of that available time
into an educational experience. I guarantee you'll learn a lot in the
process. If you want to learn even more about phased arrays, see Chapter 8
of the _ARRL Antenna Book_. The phased array section was completely
rewritten and updated for the latest (21st) edition.

Roy Lewallen, W7EL

Thank you, Roy. Seriously. I've been putting off trying EZNEC out, but
guess it's been long enough. Like you say, time to put some of my spare
time into a serious learning experience. Thank you for that link, too. Now
I have no excuses. :)

I do appreciate your feedback, and encouragement. Sorry if I was being
lazy. I really don't know why I've been putting it off, but I realize now
that I have.

'preciate it.

Dave

PS: Thanks too for the tip on the latest edition of the ARRL Antenna
Handbook. Now I know I need to get that edition, and not an older one.

Probably a stupid question, but...
 

"Owen Duffy" wrote in message
...
"Dave" wrote in
:

...
were easy to install. Seems I read somewhere that contrary to
conventional wisdom, the shield on a shielded loop doesn't actually
shield at all, but becomes the antenna element. Anyone know anything
about that line of thought? I obviously know nothing, and am trying
to learn. Just don't know where to focus my energies.

I have written a simple explanation on the operation of the so called
'shielded loop' at http://www.vk1od.net/shieldedloop/index.htm .

You may find the article of interest.

If you read and understand the content of the article, you will see the
pitfalls in using tape to 'shield' a loop.

Owen

Hello Owen,

Sorry I am just now getting back to you on this, but I have been reading and
studying your article. I constructed a loop somewhat like the one you
discuss, but have one question: you speak of a "feed tee" from which the
feedline extends. Should I be able to buy such a T-shaped device at my
local parts outlet? I asked about such there one time, and was practically
laughed at. But it seems such would be very handy for antenna builders of
all types. If my local parts distributer doesn't have this item, where can
I get it and what should I call it ("feed tee"?)

The loop I constructed is extremely primitive, but still functions nearly as
well as the 110' longwire antenna I have used for years. And it is
*directional*, though sometimes noisy (probably because the feedline does
*not* exit and travel symmetrically away from the loop, I am guessing.)

The main way in which my loop differs from your design (other than the
feedline asymmetry) is the fact that the shield is not cut away from the
center conductor opposite the feed input. Can you tell me what function
this feature serves?

Thanks for your help.

Dave

Probably a stupid question, but...
 

On Thu, 27 Sep 2007 09:03:47 -0500, "Dave" wrote:

The main way in which my loop differs from your design (other than the
feedline asymmetry) is the fact that the shield is not cut away from the
center conductor opposite the feed input. Can you tell me what function
this feature serves?

Hi Dave,

It means there's a cognitive slip between you and Owen (and what is
generally constructed as a "shielded loop").

The cut-away is the feedpoint of the antenna. The two semicircular
sides extending away from it are the dipole arms (or the complete
loop, if you prefer), and the join with trailing feedline is just
that.

You would do well to more completely describe your differences as an
open must exist somewhere in the shield (yes, an irony for what is
called a "shielded loop") for it to work as an antenna.

73's
Richard Clark, KB7QHC

Probably a stupid question, but...
 

"Richard Clark" wrote in message
...
On Thu, 27 Sep 2007 09:03:47 -0500, "Dave" wrote:

The main way in which my loop differs from your design (other than the
feedline asymmetry) is the fact that the shield is not cut away from the
center conductor opposite the feed input. Can you tell me what function
this feature serves?

Hi Dave,

It means there's a cognitive slip between you and Owen (and what is
generally constructed as a "shielded loop").

The cut-away is the feedpoint of the antenna. The two semicircular
sides extending away from it are the dipole arms (or the complete
loop, if you prefer), and the join with trailing feedline is just
that.

You would do well to more completely describe your differences as an
open must exist somewhere in the shield (yes, an irony for what is
called a "shielded loop") for it to work as an antenna.

73's
Richard Clark, KB7QHC

Hey Richard,

Thanks for the quick reply.

When you say that the cutaway is the feedpont of the antenna, does that mean
it is where the received signal enters the antenna? And the feedline is
where it is carried to the receiver?

Many thanks,

Dave

Probably a stupid question, but...
 

"Dave" wrote in
:

....
Hello Owen,

Sorry I am just now getting back to you on this, but I have been
reading and studying your article. I constructed a loop somewhat like
the one you discuss, but have one question: you speak of a "feed tee"
from which the feedline extends. Should I be able to buy such a
T-shaped device at my local parts outlet? I asked about such there
one time, and was practically laughed at. But it seems such would be
very handy for antenna builders of all types. If my local parts
distributer doesn't have this item, where can I get it and what should
I call it ("feed tee"?)

Dave, the 'feed tee' I refer to is the tee at the bottom of Fig 1. It is
not a standard component that you would buy off the shelf. I have used it
as a descriptive term, sorry if it has confused you. The important detail
is the electrical detail. In commercial loop constructions, the thing is
usually a box, the the loop coax enters opposite sides of the box with
effective circumfrential shielding. The box is a convenient mounting and
good location for an amplifier if used.


The loop I constructed is extremely primitive, but still functions
nearly as well as the 110' longwire antenna I have used for years.
And it is *directional*, though sometimes noisy (probably because the
feedline does *not* exit and travel symmetrically away from the loop,
I am guessing.)

I am not suggesting that loops aren't directional. Shielding a loop is
one (and only one of several) of maximising the pattern nulls.

Symmetry helps to ensure that the feedline is not effectively part of the
system radiator.

The noise issue may be related to the above.


The main way in which my loop differs from your design (other than the
feedline asymmetry) is the fact that the shield is not cut away from
the center conductor opposite the feed input. Can you tell me what
function this feature serves?

I don't understand just what you mean. Perhaps your construction is like
Fig 3 (from the ARRL Antenna Handbook), but as stated, it doesn't do what
they say it does. That is not to say it doesn't 'work', or that it isn't
directional. The stuff about shielding against electric and not magnetic
fields is a flawed explanation.

The real radiator is the outside of the outer conductor, the feedpoint is
the gap, and the construction is a clever way of achieving maximum
symmetry by placing the feedpoint at the top and routing the coax to the
feedpoint in a way that is symmetrical with respect to the outside of the
outer conductor of the loop. If you don't route the coax away from the
tee in a very symmetrical way, don't waste your time on the complicated
construction.

Owen

Probably a stupid question, but...
 

On Thu, 27 Sep 2007 09:52:39 -0500, "Dave" wrote:

When you say that the cutaway is the feedpont of the antenna, does that mean
it is where the received signal enters the antenna? And the feedline is
where it is carried to the receiver?

Hi Dave,

The single turn, shorted loop with an open shield is merely a
convenient construction. It brings nothing new to the table of RF.

Owen's page pretty much describes it all, but there's always the
off-chance it needs to be said again.

The gap is the feedpoint driving your transmission line.

The gap and driveline drop must be at the points shown for symmetry to
insure balance.

Shielding does nothing but describe a balance. You can as easily
remove the shield and obtain identical performance IF you guarantee
balance. This was done for decades before coaxial cable was common.

The gap, the short, and the shield all lend the aura of "magic" to an
otherwise conventional loop. Being "magic" gives rise to ridiculous
claims applied to it. Being "magic" divorces logic from the design.
That loss of logic begins to migrate among the "magic" crowd such that
they come up with useless antennas.

73's
Richard Clark, KB7QHC

Probably a stupid question, but...
 

Richard Clark wrote in
:

Shielding does nothing but describe a balance. You can as easily
remove the shield and obtain identical performance IF you guarantee
balance. This was done for decades before coaxial cable was common.

Hi Richard,

For Dave's benefit, I might explain that the risk attendent in using a
small loop on a long transmission line is that the outside of the
transmission line becomes a significant radiator. In the limit, the loop
becomes just a means of exciting the outside of the transmission line as
the main element of the antenna system.

That is often undesirable because it spoils the pattern and / or results
in pickup of undesirable signals, especially from sources close to the
transmission line that has become the antenna.

There are other methods of trying to isolate the transmission line (as
Richard noted), the shielded loop construction is not the only way. For
example, a BALUN is a device that is designed to permit transition from
an balance device (the loop) to an unbalanced device (a coaxial
transmission line).

The shielded loop is widely used for instrumentation purposes, where the
Antenna Factor (related to gain) is calibrated and needs to be
independent of feedline length and routing (within reason).

Owen

Probably a stupid question, but...
 

"Owen Duffy" wrote in message
...
"Dave" wrote in
:

...
Hello Owen,

Sorry I am just now getting back to you on this, but I have been
reading and studying your article. I constructed a loop somewhat like
the one you discuss, but have one question: you speak of a "feed tee"
from which the feedline extends. Should I be able to buy such a
T-shaped device at my local parts outlet? I asked about such there
one time, and was practically laughed at. But it seems such would be
very handy for antenna builders of all types. If my local parts
distributer doesn't have this item, where can I get it and what should
I call it ("feed tee"?)

Dave, the 'feed tee' I refer to is the tee at the bottom of Fig 1. It is
not a standard component that you would buy off the shelf. I have used it
as a descriptive term, sorry if it has confused you. The important detail
is the electrical detail. In commercial loop constructions, the thing is
usually a box, the the loop coax enters opposite sides of the box with
effective circumfrential shielding. The box is a convenient mounting and
good location for an amplifier if used.


The loop I constructed is extremely primitive, but still functions
nearly as well as the 110' longwire antenna I have used for years.
And it is *directional*, though sometimes noisy (probably because the
feedline does *not* exit and travel symmetrically away from the loop,
I am guessing.)

I am not suggesting that loops aren't directional. Shielding a loop is
one (and only one of several) of maximising the pattern nulls.

Symmetry helps to ensure that the feedline is not effectively part of the
system radiator.

The noise issue may be related to the above.


The main way in which my loop differs from your design (other than the
feedline asymmetry) is the fact that the shield is not cut away from
the center conductor opposite the feed input. Can you tell me what
function this feature serves?

I don't understand just what you mean. Perhaps your construction is like
Fig 3 (from the ARRL Antenna Handbook), but as stated, it doesn't do what
they say it does. That is not to say it doesn't 'work', or that it isn't
directional. The stuff about shielding against electric and not magnetic
fields is a flawed explanation.

The real radiator is the outside of the outer conductor, the feedpoint is
the gap, and the construction is a clever way of achieving maximum
symmetry by placing the feedpoint at the top and routing the coax to the
feedpoint in a way that is symmetrical with respect to the outside of the
outer conductor of the loop. If you don't route the coax away from the
tee in a very symmetrical way, don't waste your time on the complicated
construction.

Owen

Hey Owen,

I am unclear on the use of the term "feedpoint" to describe the exposed
center conductor of the coax. Can you give me a little more detail as to
what this means? Sorry, I just don't understand why it is called the
feedpoint. I somehow thought that was where the coax connecting the antenna
to the receiver/transmitter was attached. And just for the record, I am
only going to be receiving with whatever type of loop I end up with. What
I am actually seeking is a small loop that I can attach to my tunable RF
amplifier for feeding enhanced signal to my Sony 7600GR shortwave radio,
making a portable unit to pair with the radio, allowing me to set them both
up wherever I wish.

Oh, and the primitive loop I currently have is a piece of coax forming an
(approx) 18" loop, with the center conductor connected to the outer shield
and none of the shield cut away.

Thanks again for your help...

Dave

Probably a stupid question, but...
 

"Dave" wrote in
:


"Owen Duffy" wrote in message
...
"Dave" wrote in
:

...
Hello Owen,

Sorry I am just now getting back to you on this, but I have been
reading and studying your article. I constructed a loop somewhat
like the one you discuss, but have one question: you speak of a
"feed tee" from which the feedline extends. Should I be able to buy
such a T-shaped device at my local parts outlet? I asked about such
there one time, and was practically laughed at. But it seems such
would be very handy for antenna builders of all types. If my local
parts distributer doesn't have this item, where can I get it and
what should I call it ("feed tee"?)

Dave, the 'feed tee' I refer to is the tee at the bottom of Fig 1. It
is not a standard component that you would buy off the shelf. I have
used it as a descriptive term, sorry if it has confused you. The
important detail is the electrical detail. In commercial loop
constructions, the thing is usually a box, the the loop coax enters
opposite sides of the box with effective circumfrential shielding.
The box is a convenient mounting and good location for an amplifier
if used.


The loop I constructed is extremely primitive, but still functions
nearly as well as the 110' longwire antenna I have used for years.
And it is *directional*, though sometimes noisy (probably because
the feedline does *not* exit and travel symmetrically away from the
loop, I am guessing.)

I am not suggesting that loops aren't directional. Shielding a loop
is one (and only one of several) of maximising the pattern nulls.

Symmetry helps to ensure that the feedline is not effectively part of
the system radiator.

The noise issue may be related to the above.


The main way in which my loop differs from your design (other than
the feedline asymmetry) is the fact that the shield is not cut away
from the center conductor opposite the feed input. Can you tell me
what function this feature serves?

I don't understand just what you mean. Perhaps your construction is
like Fig 3 (from the ARRL Antenna Handbook), but as stated, it
doesn't do what they say it does. That is not to say it doesn't
'work', or that it isn't directional. The stuff about shielding
against electric and not magnetic fields is a flawed explanation.

The real radiator is the outside of the outer conductor, the
feedpoint is the gap, and the construction is a clever way of
achieving maximum symmetry by placing the feedpoint at the top and
routing the coax to the feedpoint in a way that is symmetrical with
respect to the outside of the outer conductor of the loop. If you
don't route the coax away from the tee in a very symmetrical way,
don't waste your time on the complicated construction.

Owen

Hey Owen,

I am unclear on the use of the term "feedpoint" to describe the
exposed center conductor of the coax. Can you give me a little more
detail as to what this means? Sorry, I just don't understand why it
is called the feedpoint. I somehow thought that was where the coax
connecting the antenna to the receiver/transmitter was attached. And

I have used the term feedpoint to denote the point that delimits the role
of the transmission line and the radiator.

just for the record, I am only going to be receiving with whatever
type of loop I end up with. What I am actually seeking is a small

Ok, but broady speaking, the effects that apply to considering the antenna
with a tranmsmitter also apply to using it as a receiver.

If you want to think in receive terms, your coax feed line may have RF
currents induced on the outside of it from local and distant sources, and
if at the tee at the bottom of the loop, that current divides equally into
both halves of the loop, it will not result in a voltage difference at the
gap. The current will only divide to equally if each side of the loop is
symmetrical to the feed line and everything else near to it.

loop that I can attach to my tunable RF amplifier for feeding enhanced
signal to my Sony 7600GR shortwave radio, making a portable unit to
pair with the radio, allowing me to set them both up wherever I wish.

Oh, and the primitive loop I currently have is a piece of coax forming
an (approx) 18" loop, with the center conductor connected to the outer
shield and none of the shield cut away.

Again, I think you are describing the loop shown in Fig 3 of my article.
You don't need to use coax for the loop itself, it is not a balanced loop
as described and coax doesn't help with balance. If it was you intention
that the loop was not susceptible to pickup on the feedline, the antenna
you describe does nothing to prevent that. The shielding explanation for
that type of loop is bunk.


Owen

Probably a stupid question, but...
 

"Owen Duffy" wrote in message
...
"Dave" wrote in
:


"Owen Duffy" wrote in message
...
"Dave" wrote in
:

...
Hello Owen,

Sorry I am just now getting back to you on this, but I have been
reading and studying your article. I constructed a loop somewhat
like the one you discuss, but have one question: you speak of a
"feed tee" from which the feedline extends. Should I be able to buy
such a T-shaped device at my local parts outlet? I asked about such
there one time, and was practically laughed at. But it seems such
would be very handy for antenna builders of all types. If my local
parts distributer doesn't have this item, where can I get it and
what should I call it ("feed tee"?)

Dave, the 'feed tee' I refer to is the tee at the bottom of Fig 1. It
is not a standard component that you would buy off the shelf. I have
used it as a descriptive term, sorry if it has confused you. The
important detail is the electrical detail. In commercial loop
constructions, the thing is usually a box, the the loop coax enters
opposite sides of the box with effective circumfrential shielding.
The box is a convenient mounting and good location for an amplifier
if used.


The loop I constructed is extremely primitive, but still functions
nearly as well as the 110' longwire antenna I have used for years.
And it is *directional*, though sometimes noisy (probably because
the feedline does *not* exit and travel symmetrically away from the
loop, I am guessing.)

I am not suggesting that loops aren't directional. Shielding a loop
is one (and only one of several) of maximising the pattern nulls.

Symmetry helps to ensure that the feedline is not effectively part of
the system radiator.

The noise issue may be related to the above.


The main way in which my loop differs from your design (other than
the feedline asymmetry) is the fact that the shield is not cut away
from the center conductor opposite the feed input. Can you tell me
what function this feature serves?

I don't understand just what you mean. Perhaps your construction is
like Fig 3 (from the ARRL Antenna Handbook), but as stated, it
doesn't do what they say it does. That is not to say it doesn't
'work', or that it isn't directional. The stuff about shielding
against electric and not magnetic fields is a flawed explanation.

The real radiator is the outside of the outer conductor, the
feedpoint is the gap, and the construction is a clever way of
achieving maximum symmetry by placing the feedpoint at the top and
routing the coax to the feedpoint in a way that is symmetrical with
respect to the outside of the outer conductor of the loop. If you
don't route the coax away from the tee in a very symmetrical way,
don't waste your time on the complicated construction.

Owen

Hey Owen,

I am unclear on the use of the term "feedpoint" to describe the
exposed center conductor of the coax. Can you give me a little more
detail as to what this means? Sorry, I just don't understand why it
is called the feedpoint. I somehow thought that was where the coax
connecting the antenna to the receiver/transmitter was attached. And

I have used the term feedpoint to denote the point that delimits the role
of the transmission line and the radiator.

just for the record, I am only going to be receiving with whatever
type of loop I end up with. What I am actually seeking is a small

Ok, but broady speaking, the effects that apply to considering the antenna
with a tranmsmitter also apply to using it as a receiver.

If you want to think in receive terms, your coax feed line may have RF
currents induced on the outside of it from local and distant sources, and
if at the tee at the bottom of the loop, that current divides equally into
both halves of the loop, it will not result in a voltage difference at the
gap. The current will only divide to equally if each side of the loop is
symmetrical to the feed line and everything else near to it.

loop that I can attach to my tunable RF amplifier for feeding enhanced
signal to my Sony 7600GR shortwave radio, making a portable unit to
pair with the radio, allowing me to set them both up wherever I wish.

Oh, and the primitive loop I currently have is a piece of coax forming
an (approx) 18" loop, with the center conductor connected to the outer
shield and none of the shield cut away.

Again, I think you are describing the loop shown in Fig 3 of my article.
You don't need to use coax for the loop itself, it is not a balanced loop
as described and coax doesn't help with balance. If it was you intention
that the loop was not susceptible to pickup on the feedline, the antenna
you describe does nothing to prevent that. The shielding explanation for
that type of loop is bunk.


Owen

Okay, well, all I am trying to do is build something that will pick up weak
signals from a given direction, while ignoring signals and noise from other
directions. Ideally, it would not introduce a great deal of noise from any
source (unlike the loop I currently am experimenting with.) I am not overly
enamored of complex designs, and don't really care what it looks like so
long as it meets the above criteria. Do you know of any fairly simple
designs that would meet this description? If tuning is possible, that would
be a plus.

Thanks,

Dave

Probably a stupid question, but...
 

"Dave" wrote in
:

Okay, well, all I am trying to do is build something that will pick up
weak signals from a given direction, while ignoring signals and noise
from other directions. Ideally, it would not introduce a great deal
of noise from any source (unlike the loop I currently am experimenting
with.) I am not overly enamored of complex designs, and don't really
care what it looks like so long as it meets the above criteria. Do
you know of any fairly simple designs that would meet this
description? If tuning is possible, that would be a plus.

For your MW RO application, I would look at a multi turn (unshielded)
loop, untuned or tuned, but with an effective balun isolating the outer
surface of the outer conductor of the coax feed line from the loop.

I responded originally to your question about shielded loops. Shielding
is only one way to improve loop balance, and most explanations of
shielded loops are flawed.

Google for some designs, and be suspicious of purported shielded loops.

BTW, loops have pattern symmetry about the plane of the loop, so they
don't favour signals from only one direction. Think of them more as
having two diametrically opposed narrow reject regions in the patter, the
two accept regions are much broader. If you want maximum rejection,
balance the loop wrt the feed line and everything else near it.

Owen

Probably a stupid question, but...
 

On Sep 27, 7:48 pm, "Dave" wrote:


Again, I think you are describing the loop shown in Fig 3 of my article.
You don't need to use coax for the loop itself, it is not a balanced loop
as described and coax doesn't help with balance. If it was you intention
that the loop was not susceptible to pickup on the feedline, the antenna
you describe does nothing to prevent that. The shielding explanation for
that type of loop is bunk.

Owen

Okay, well, all I am trying to do is build something that will pick up weak
signals from a given direction, while ignoring signals and noise from other
directions. Ideally, it would not introduce a great deal of noise from any
source (unlike the loop I currently am experimenting with.) I am not overly
enamored of complex designs, and don't really care what it looks like so
long as it meets the above criteria. Do you know of any fairly simple
designs that would meet this description? If tuning is possible, that would
be a plus.

Thanks,

Dave

One thing about small loops.. They are great at nulling ground wave
signals,
but not so great at nulling skywave signals.
So how well a small loop would work will depend on the source of the
noise.
If the source is local, IE: a noisy power line, etc, that signal will
arrive via
a space or ground wave, and you can null that noise very well.
But if the interference is via sky wave, you might get a reduction in
strength,
but usually not a total null.
As a general rule, small loops are best suited to the lower
frequencies.
They work ok for the HF bands, but you may not the see all the
benefits
on those bands that you might on the MW bands. But even one used
for HF should get a decent null on a noise signal as long as the
source
is fairly local.
As far as shielded loops, I've carefully compared both unshielded and
shielded loops, and couldn't really tell a lick of difference as long
as
both are balanced. I've also tried using unshielded loops, but with a
shielded coupling loop. Again, no difference, as mine are fairly well
balanced even using a regular unshielded solenoid loop.
I had just as deep nulls unshielded, as I did shielded.. No difference
in perceived noise either. So I consider using shielded loops an
option,
but usually not needed. As many have mentioned , the only advantage
is to help ensure balance, and in most cases, it's not a problem to
worry about.
I do mount everything very symmetrically though. I make mine with
very simple PVC frames.
IE: one example... http://web.wt.net/~nm5k/loop5.jpg
But my big one is even more simple. Just a thick appx 2-3 inch PVC
"mast", and regular 3/4 inch PVC for a cross arm, using PVC "Tees"
at the ends to thread the wires through.
The 3/4 inch PVC crossarm is run through drilled holes in the larger
PVC
mast. I drill them to fit tight, and I don't even have to glue them,
although
thats an option. I use stands to mount the loops on, and they can be
easily turned.
MK

Probably a stupid question, but...
 

Dave wrote:

I am unclear on the use of the term "feedpoint" to describe the exposed
center conductor of the coax. Can you give me a little more detail as to
what this means? Sorry, I just don't understand why it is called the
feedpoint. I somehow thought that was where the coax connecting the antenna
to the receiver/transmitter was attached. And just for the record, I am
only going to be receiving with whatever type of loop I end up with. What
I am actually seeking is a small loop that I can attach to my tunable RF
amplifier for feeding enhanced signal to my Sony 7600GR shortwave radio,
making a portable unit to pair with the radio, allowing me to set them both
up wherever I wish. . .

I might be able to shed a little more light on this.

If you directly feed an unshielded loop, you cut a gap in the loop and
connect a transmission line across it. Current induced in the loop by a
signal flows from the loop to the transmission line via this connection.

In a "shielded" loop, the signal induces a current on the outside of the
"shield". At the gap, the current flows to the inside of the "shield"
where it induces an equal and opposite current into the inner loop
itself. The inside of the "shield" and the inner loop comprise an
ordinary non-radiating coaxial transmission line, so it can be said that
the gap is where the signal-induced current enters the transmission
line, just like the gap in the unshielded loop. And so the gap in the
"shielded" loop is a feedpoint in exactly the same sense as the gap in
an unshielded loop.

Roy Lewallen, W7EL

Probably a stupid question, but...
 

Richard Clark wrote:



The gap, the short, and the shield all lend the aura of "magic" to an
otherwise conventional loop.

One of the first things I learned in my RF education is that a
gap does not necessarily stop the flow of RF, and neither does
a short! The mysteries of shielding I am still learning about.

I thought I had it all nicely sorted out, and then along came
the Fractal antenna! :-)

Irv VE6BP