On Feb 27, 11:16 am, "JIMMIE" wrote:

no need to be surprised at having an antenna with elements that are
all phased. I doubt if ther is anyone on the news group that doesnt
know that a Yagi Uda antenna doesnt represent some kind of comprimise
to an antenna with all of the elements feed. No one has ever said
otherwise although you have claimed they have.

The problem with having all the elements feed is that it is
impractical to control power distribution and phasing when changing
frequencies.

This is just not true. A SteppIR does it mechanically by changing the
element lengths. A 4 square does it by switching ports around on a
phasing network. One can buy everything you need to build a generic 4
element HF phased array with computer adjustable LC networks for less
than a few thousand dollars. (see, e.g. LDG's AT200PC tuner with an
RS232 interface)

The Yagi Uda overcomes this problem at a slight cost in
gain. Your idea of an antenna with multiple fed resonant elements is a
giant step backwards to a day when high gain steerable antennas were
impractical most of the hams who didnt have the money or the real
estate for huge arrays

hardly backwards. Phased arrays may well save the day in this era of
ever increasing community resistance to traditional Beam on rotator on
tower installations.

Antenna with multiple resonant element all being fed is very common in
RADAR and space communication, you can achive very high gains in this
manner just as you have stated.

You can get low gains too. or just sharp adjustable nulls, which is
probably more useful.

It is also very expensive, has narrow
bandwidth and is a mechanical nightmare.

Expensive compared to what? We're not talking about a electronically
steered phased array radar here with thousands of elements. I'll bet
the hardware cost of a electronically steered phased array for HF
suitable for ham use is comparable to the hardware cost of a big
tower, rotator, and Yagi.. the phased array just isn't available as an
off the shelf product yet.


NASA, AM BCB, commercial
shortwave stations and various other agencies and private companies
sometimes have a need for this type of antenna and they they have the
money to build them, few hams do.

A ham could build an adjustable directional array of verticals,
essentially identical to an AM broadcast directional array, for
several thousand dollars. Yep, that's a bunch o'bux compared to a
Rockmite and a wire over the balcony railing. But it's not a bunch
o'bux in the context of a big station with a legal limit amp, a state
of the art transceiver, etc. If you're willing to homebrew and
scrounge, you can build computer controlled phasing networks with
stepper motors (or servos), roller inductors and variable caps.
Adjusting it is non trivial, but so is learning Morse code, or how to
use NEC or lots of other things in ham radio.. it's just not
particularly common. All the math and design information is laid out
in detail in ON4UN's book, with the implementation left "as an
exercise for the reader".

Jim, W6RMK

wrote in message
ps.com...
On Feb 27, 11:16 am, "JIMMIE" wrote:
the phased array just isn't available as an
off the shelf product yet.

sure it is, i have one for 80m, and one for 40m that were off the shelf
phasing systems... comtek sells lots of them. and i have a home made one
for 160m.

On 27 Feb, 17:12, "Dave" wrote:
wrote in message

ps.com...

On Feb 27, 11:16 am, "JIMMIE" wrote:
the phased array just isn't available as an
off the shelf product yet.

sure it is, i have one for 80m, and one for 40m that were off the shelf
phasing systems... comtek sells lots of them. and i have a home made one
for 160m.

Look guys all of this is very silly, seems like the interest is more
fore arguments sake
than the search for the real truth. I beg you to use Google to read up
on a conservative field,
it probably will be insinia or something like that.
It clearly states that curl is part and parcel of what constitutes a
concervative field.
Now in this case they point out that curl is zero but at the same time
they point out it cannot be left out and state why. So you all that
are so clever can scan the bottom where an indication on further
information is given on curl. Following up on that tip who find an
expresion that includes time i.e. dt. But you are comfortable with
expedias discussion on conservative fields
and as Roy would say as an out, I don't understand! So we look at the
mathematics and decide for a conservative field there are only two
cartesian dimensions used in the equation and we all are aware that
it is paramount when dealing with equations equilibrium must be
maintained at all times and you cannot destable an "equal " sign".
Since curl was stated in dt terms when we looked it up to maintain
equilibrium on both sides of the equation which extends Gaussian law
with " the adition of a moment in time". All very simple, all laws
are followed and equilibrium is maintained. All we have done is used
all cartesian vectors instead of just two which allows us to broarden
the equation to include a time variant field. Gentlemen this is what
it is all about! I know many are not interested and look at it as an
opportunity to spout off. Some with a bit of education say whoa
you can't do that, but for why? Some people want me to write out
mathematical formula which my keyboard is not capable of but why not
argue with expedia instead of me. Now it is being said by some that it
is acknoweledged that the yagi can be beaten! Does your NEC program
confirm that with a sample or does it always print off a yagi. If you
have got a program that can test that out then do it for your own
good. If you haven't then point out the mathematical errors stated if
not for your own good and satisfaction. I know it is difficult to get
a horse to drink but eventually one comes along unaware of the
situation tries things for himself and then looks up and ask what
everybody is waiting for! I have given two areas that you can research
in moments
so that you can debate my errors.For goodneas sake put aside all
pettines and one upman ship and show all that you really are men.If
you are a mathematician then debate around that point. If you are just
a hobbyist but have a computor program then follow that route to cut
me down, but do something that is worthwhile. How many have an answer
to the computor test I gave, probably nobody because their findings
were embareasing. Who with a knoweledge of physics is willing to put
his stake in the ground and debate from that side, probably none. Quit
babling about "I want"
and think more in line with "I can"
Art
Art

"Dave" wrote in message
news:4G4Fh.15798$sv6.284@trndny08...

wrote in message
ps.com...
On Feb 27, 11:16 am, "JIMMIE" wrote:
the phased array just isn't available as an
off the shelf product yet.

sure it is, i have one for 80m, and one for 40m that were off the shelf
phasing systems... comtek sells lots of them. and i have a home made one
for 160m.


And 160 and 80 and 40 is where these antennas have there niche. Where the
big yagi isnt so popular or practical. I wouldnt think of putting up a Yagi
for 80 either but I might put of a couple of towers I can run in or out of
phase.

Jimmie

Jim wrote:
I'll bet the hardware cost of a electronically steered phased array
for HF suitable for ham use is comparable to the hardware cost of a big
tower, rotator, and Yagi.. the phased array just isn't available as an
off the shelf product yet.


The fully steerable phased array that can also handle 1.5kW TX power is
not available as a HAM product off the shelf yet... but we can already
see where the future is headed.

Many people already have four-square phased arrays for the lower HF
bands, but we have hardly begun to tap their true potential.

The design company Plextek has a downloadable demonstration which shows
what a four-square phased array can really do:
http://download.plextek.co.uk/AKS06.zip

The user interface is a bit clunky, but stay with it...

The program starts with an omnidirectional pattern, receiving signal 1
coming from 90deg (blue arrow at 3 o'clock). The thermometer bar at the
top right is showing a positive signal/noise ratio (green).

Click in the 'Interferers' columns to bring up either one or two
interfering stations which are the yellow arrows. The thermometer bar
now shows a negative s/n ratio on the wanted signal (red).

Now the fun starts: in the 'Algorithm' column, click on 'SMART' to turn
on Plextek's proprietary adaptive array software - watch the phased
array reconfigure itself automatically. The pattern adapts to null out
*both* of the interfering signals, while still keeping a lobe pointing
towards the wanted signal. The wanted signal reappears from under the
QRM and its s/n ratio increases dramatically.

You can then drag the interfering signals to different directions, and
the array keeps on adapting. The only case where it can't give any
improvement is where the interfering signal comes from exactly the same
direction as the wanted signal.

All this is done by varying the amplitude and phasing of the signals
from each of the elements before combining them. The 'WEIGHTS' table at
centre right shows what is required. On transmit, the same directional
patterns could be achieved by applying the same weightings to the
currents that are fed to the four elements - or of course you could
switch to a different pattern while transmitting.

OK, this is only a demonstration. It doesn't consider signals at a range
of different vertical angles; it doesn't consider the big practical
problems of achieving the correct current weightings when all four
elements are interacting; and it doesn't consider how to handle the TX
power. Even so, it will open your eyes to what a phased array can really
do.

It's all down to the magic phasing box at the centre of the array.
Whatever goes into that box will be hard to design, complicated to
control, and expensive to build... but most four-square owners would be
happy to have even a fraction of those extra capabilities.


--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

On Feb 28, 12:29 am, Ian White GM3SEK wrote:
Jim wrote:
I'll bet the hardware cost of a electronically steered phased array
for HF suitable for ham use is comparable to the hardware cost of a big
tower, rotator, and Yagi.. the phased array just isn't available as an
off the shelf product yet.

The fully steerable phased array that can also handle 1.5kW TX power is
not available as a HAM product off the shelf yet... but we can already
see where the future is headed.

---------
snip
----------
It's all down to the magic phasing box at the centre of the array.
Whatever goes into that box will be hard to design, complicated to
control, and expensive to build... but most four-square owners would be
happy to have even a fraction of those extra capabilities.

I think it might be a bit of time before it's an off the shelf product
(lack of demand is part of the reason).
It also depends a bit on just how good you want the performance to be
(null depth, primarily.. forward gain is not very sensitive to phasing
and amplitude accuracy), and whether you want to make it an antenna
system that just hooks onto an existing rig and PA, essentially
hanging off a single feedline, or whether a higher level of
integration is desirable or feasible. (for instance, rather than power
combining a bunch of solid state amp modules like the current kilowatt
class SSPAs do, put a power module on each antenna)

"the magic box in the center of the array" is more the former model,
and while simple conceptually, in the long run probably isn't the best
way to solve the problem in a system context. For instance, a multi
channel receiver, which can do all the phasing, very precisely, at low
levels, either with analog or digital processing, can give you the
nice deep nulls and adaptation.For TX, though, null depth isn't as
important as maximizing the power squirted in the right direction.

Hardware wise, the design isn't particularly complicated (any of the
current crop of automatic antenna tuners can serve as the building
block). Hard to control is mostly a matter of calibration and the
right algorithms (and, yes, non trivial, but so is building a tetrode
or FET power amp that's stable from 10 to 160, etc.). Expensive is
more a matter of "compared to what".. You can buy a kilowatt autotuner
for $500, so, assuming you needed 8 of them to control 4 elements (a
single L network can only give you 90 degrees of phase shift, and you
need 180).. that's $4K. Probably need some relays and transformers,
as well as controller. I'd figure $6K, today.. But that's "off the
shelf" assemblies. and not purpose designed. Start comparing that to
the $10K to put up a tower and a Yagi (comparing new prices to new
prices, plus building permits, etc.) and the phased array starts to be
competive.

So.. not today, but I'd figure that in 10 years, you'll start to see
real broadband phased arrays (not just 4-8 switched beams in a single
band like a 4 square). They provide a real solution to restricted
space installations, if nothing else, because you can make effective
use of the "volume" of space within a small suburban lot (i.e. the max
theoretical gain from an antenna that fits in a box that's say,
15x30x10 meters is pretty high).

Jim, W6RMK

On 28 Feb, 23:20, wrote:
On Feb 28, 12:29 am, Ian White GM3SEK wrote: Jim wrote:
I'll bet the hardware cost of a electronically steered phased array
for HF suitable for ham use is comparable to the hardware cost of a big
tower, rotator, and Yagi.. the phased array just isn't available as an
off the shelf product yet.

The fully steerable phased array that can also handle 1.5kW TX power is
not available as a HAM product off the shelf yet... but we can already
see where the future is headed.

---------
snip
----------
snipe). They provide a real solution to restricted
space installations, if nothing else, because you can make effective
use of the "volume" of space within a small suburban lot (i.e. the max
theoretical gain from an antenna that fits in a box that's say,
15x30x10 meters is pretty high).

Jim, W6RMK

Jim, this volume approach to gain versus linear length comparison
sounds very interesting but I have not seen any reference to it
anywhere. Basically a gaussian array say for a single feed point
makes full use of volume where other antennas which are of planar form
lose out. With a planar design one can extrapolate gain by number of
elements combined with length e.t.c but I have not seen any such gain
calculation for a volume,can you help me there?
I have found that the number of elements with respect to contained
volume is a good measurement where the array is contained within the
1/2 wave length cubed beyond which it appears to have reached its
maximum. This means having covered a real estate area of half that of
a yagi but with equivalent gain.
Ofcourse one can gang arrays together if one uses multiple feeds
but I haven't personaly pursued that approach as yet.
Glad to see you posting, most informative
Best regards
Art

Jim wrote:
On Feb 28, 12:29 am, Ian White GM3SEK wrote:
Jim wrote:
I'll bet the hardware cost of a electronically steered phased array
for HF suitable for ham use is comparable to the hardware cost of a big
tower, rotator, and Yagi.. the phased array just isn't available as an
off the shelf product yet.

The fully steerable phased array that can also handle 1.5kW TX power is
not available as a HAM product off the shelf yet... but we can already
see where the future is headed.

---------
snip
----------
It's all down to the magic phasing box at the centre of the array.
Whatever goes into that box will be hard to design, complicated to
control, and expensive to build... but most four-square owners would be
happy to have even a fraction of those extra capabilities.

I think it might be a bit of time before it's an off the shelf product
(lack of demand is part of the reason).
It also depends a bit on just how good you want the performance to be
(null depth, primarily.. forward gain is not very sensitive to phasing
and amplitude accuracy), and whether you want to make it an antenna
system that just hooks onto an existing rig and PA, essentially
hanging off a single feedline, or whether a higher level of
integration is desirable or feasible. (for instance, rather than power
combining a bunch of solid state amp modules like the current kilowatt
class SSPAs do, put a power module on each antenna)

"the magic box in the center of the array" is more the former model,
and while simple conceptually, in the long run probably isn't the best
way to solve the problem in a system context.

That is very true. Unfortunately, the ham market is divided up into
physically separate compartments of transceivers, power amplifiers and
antennas. That is a severe restriction which makes all the technical
challenges much more difficult.

However, we can try to pare the problem down a little.

Another important point is that the concept of 'market demand' is
beginning to break down in ham radio. The big manufacturers are
increasingly challenged by new products that pay no attention to the
market - they spring directly from some individual or small team
deciding they're going to do it.

Then maybe the design is produced as a kit, or manufacturing is taken up
by some lower-tier company that is faster on its feet. Seems good to
me...


For instance, a multi
channel receiver, which can do all the phasing, very precisely, at low
levels, either with analog or digital processing, can give you the
nice deep nulls and adaptation.For TX, though, null depth isn't as
important as maximizing the power squirted in the right direction.

That seems a good place to cut the problem down to size. By all means
continue to use the existing phasing networks for TX, with 4 or 8
switchable directions and fixed phasing; but switch the antennas over to
a totally separate network for RX.

At the lower power levels, the RX network could be much more complex and
versatile, combining the signals from the four (say) antennas with
amplitudes and phasing that could be varied on the fly.

Another way to scale down the problem is not to be too ambitious about
automatic null steering. In ham operating it is often difficult for a
computer to identify which is the wanted signal and which is the QRM, so
maybe let's not try. Semi-automatic null steering definitely would be
within reach, where the user has a control to steer the null direction
manually for the best audible results, and the computer does the math to
select the required network parameters.


So.. not today, but I'd figure that in 10 years, you'll start to see
real broadband phased arrays (not just 4-8 switched beams in a single
band like a 4 square).

Yes, I think maybe so. We already have most of the technology for an
advanced manually steerable RX array, so it's mainly a matter of
integrating the separate parts of it to make a practical design. Someone
just has to decide to do it... and maybe they already have.


--

73 from Ian GM3SEK

On Mar 1, 11:58 am, Ian White GM3SEK wrote:




"the magic box in the center of the array" is more the former model,
and while simple conceptually, in the long run probably isn't the best
way to solve the problem in a system context.

That is very true. Unfortunately, the ham market is divided up into
physically separate compartments of transceivers, power amplifiers and
antennas. That is a severe restriction which makes all the technical
challenges much more difficult.

Dare I say that what is needed is that much overworked phrase
"paradigm shift"? It used to be that a "transceiver" was a radical
new thing, because everyone knew that you needed a separate Tx and
Rx. Oddly, with phased arrays, perhaps the transceiver becomes passe.

However, we can try to pare the problem down a little.

Another important point is that the concept of 'market demand' is
beginning to break down in ham radio. The big manufacturers are
increasingly challenged by new products that pay no attention to the
market - they spring directly from some individual or small team
deciding they're going to do it.

I think this has actually been the case for decades. I doubt, for
instance, that the KWM-1 was motivated by some massive pentup demand
for an integrated SSB transceiver.

Then maybe the design is produced as a kit, or manufacturing is taken up
by some lower-tier company that is faster on its feet. Seems good to
me...

This would be true of many things.. the SDR1000 might be an example. A
variety of TAPR kits might be another.



For instance, a multi
channel receiver, which can do all the phasing, very precisely, at low
levels, either with analog or digital processing, can give you the
nice deep nulls and adaptation.For TX, though, null depth isn't as
important as maximizing the power squirted in the right direction.

That seems a good place to cut the problem down to size. By all means
continue to use the existing phasing networks for TX, with 4 or 8
switchable directions and fixed phasing; but switch the antennas over to
a totally separate network for RX.

In fact, for HF, you can probably get away with smaller active
antennas for receive. There's no particular reason why the Tx
antennas and the Rx antennas have to be the same, since you're not
typically receiver noise figure limited. There IS a strong signal IM
problem..so maybe active receive antennas aren't the right solution.
But, there's a lot of convenience possible if your receive antennas
are all something like 6 foot whips.

At the lower power levels, the RX network could be much more complex and
versatile, combining the signals from the four (say) antennas with
amplitudes and phasing that could be varied on the fly.

You can use nifty things like the 4 quadrant vector multipliers from
Maxim, for instance.


Another way to scale down the problem is not to be too ambitious about
automatic null steering. In ham operating it is often difficult for a
computer to identify which is the wanted signal and which is the QRM, so
maybe let's not try. Semi-automatic null steering definitely would be
within reach, where the user has a control to steer the null direction
manually for the best audible results, and the computer does the math to
select the required network parameters.

That would be where I would start. Adaptive nulling is a bit weird to
work with as a user, especially if you expect to control it. And, for
hams, they want a bit more control. What would be cool is to have a
3D panoramic display that somehow indicates not only the frequency
spectrum, but the angle of arrival.
So.. not today, but I'd figure that in 10 years, you'll start to see
real broadband phased arrays (not just 4-8 switched beams in a single
band like a 4 square).

Yes, I think maybe so. We already have most of the technology for an
advanced manually steerable RX array, so it's mainly a matter of
integrating the separate parts of it to make a practical design. Someone
just has to decide to do it... and maybe they already have.

I've got most of both halves (steerable Tx array and steerable Rx
array) in pieces, but there's a lot of practical usability and
integration issues. Sure would be nice to have a wealthy patron and
have lots of free time and a big budget to work on itgrin. I
developed the in-situ calibration algorithms as part of a R&D effort
at JPL, but the resources eventually ran out. Too many projects and
too little time.

Jim, W6RMK

On 1 Mar 2007 21:16:22 -0800, wrote:

Dare I say that what is needed is that much overworked phrase
"paradigm shift"? It used to be that a "transceiver" was a radical
new thing, because everyone knew that you needed a separate Tx and
Rx. Oddly, with phased arrays, perhaps the transceiver becomes passe.

Hi Jim,

There may be life left in the transceiver to perform what you want
anyway. Just think more power.

I can sense that this discussion is leading back to a separation of
driver from amplifier. You could still use a power divider to feed
the remote amps at the various array locations. Say 10W at 10 active
antennas, each with a 100W rating.

This would preserve investment, and create and alternative to the
Henry market. Hams would have two purchase paths instead of
discarding their introductory base station and opting in for N number
of active arrays driven by a specialty item that looks like their old
rig gathering dust in the corner.

Of course, if you are talking about two or three elements, this shifts
the investment plan (but it still presumes you are willing to abandon
a prior investment). The cost-benefit of this is usually a steep
slope populated only by a few early adopters.


In fact, for HF, you can probably get away with smaller active
antennas for receive. There's no particular reason why the Tx
antennas and the Rx antennas have to be the same, since you're not
typically receiver noise figure limited.

There's no reason to expect you need a large transmit antenna for
solid state amps either. The native source resistance of a transistor
is quite low, and has to be transformed UP to match 50 Ohms. If you
had a radiation resistance of only several ohms (a very short
radiator) all you have to pay attention to is cutting Ohmic loss and
providing flexible inductance. Unfortunately, this may be a
performance killer - but if you are demanding multiband performance,
you will have to answer for this for any size array element.

There IS a strong signal IM
problem..so maybe active receive antennas aren't the right solution.

The same transceiver that survives IM would still handle it from
several phase active array elements. As you can see, redesigning a
new driver eventually leads you back to the gear you have. If you now
demand a separate receiver, separate driver, and separate active array
antennas, costs rise faster by the number of connections.

Adaptive nulling is a bit weird to
work with as a user, especially if you expect to control it. And, for
hams, they want a bit more control.

Programmable oscillators that shift immediately and start at any point
in the cycle (absolute phase AND frequency control) would be miles
further down the road.

These devices are NOT synthesizers NOR linear multipliers. They are
variable frequency look-up tables driving a DAC. You send the chip a
command of the frequency you want, and the phase angle; send the "go"
command, and the oscillator shifts from its existing frequency and
phase immediately to the new one (immediately being within one table
cell lookup).

When I looked into these 10 years ago, they (driver/DAC combination)
operated from the KHz up to about 16MHz and cost less than one XTAL
ordered to a single frequency. You still have the elemental clock osc
XTAL for processor and driver, but those litter the world for pennies.

Using this kind of technology is about the only reason I would trash
my current rigs and go for a custom driver (but it would have to
inhabit each array antenna's amp and thus render it a complete
transmitter. This would in turn cast all the features (like SSB
generation) into each of those elements. The unit cost of this would
climb because of feature creep, not component pricing.

What would be cool is to have a
3D panoramic display that somehow indicates not only the frequency
spectrum, but the angle of arrival.

This again, argues for small adaptive antennas. Now you need them in
layers.

73's
Richard Clark, KB7QHC