I had a WISP unit upgraded for better reception and they used a Yagi
antenna, at least I guess it's a Yagi. Here's a photo.

http://www.netwifiworks.com/images/a.../Yagi/yagi.png

This doesn't seem to fit the mold in a couple of ways. The elements are
not spaced at all regularly. The spacing seems to vary around a bit.
But more importantly, I've read that the director elements are
*insulated* from the support beam while these are all welded. Obviously
it works. I'm getting about 6 dB stronger signal than before although
it's a bit hard to compare as the location changed and I measured about
a 3 dB gain with the old unit in that location.

But more importantly, with the signal rising by 6 dB, the reported
background noise also rose 6 dB. Isn't SNR what is important that the
antenna should have improved?

This Yagi claims something like 20 or 25 degree beam while the old
antenna had a 60 degree beam.

--

Rick C

On 27/01/17 13:22, rickman wrote:
This Yagi claims something like 20 or 25 degree beam while the old
antenna had a 60 degree beam.
=======
That power is directed within a lower beam angle , hence more power in
the set direction of the antenna .......a favourable change.

Frank , GM0CSZ

On Fri, 27 Jan 2017 08:22:43 -0500, rickman wrote:

I had a WISP unit upgraded for better reception and they used a Yagi
antenna, at least I guess it's a Yagi. Here's a photo.
http://www.netwifiworks.com/images/a.../Yagi/yagi.png

Ok. That's an Ubiquiti AirMax AMY-9M16 900MHz antenna.
16dBi gain and dual simultaneous polarization (i.e. not switched):
https://www.ubnt.com/airmax/airmax-yagi-antenna/
https://dl.ubnt.com/datasheets/airmaxyagi/airMAX_900MHz_YAGI_Antenna.pdf
You need the dual polarization to get double the normal speed by using
2x2 MIMO streams, one per polarization.

This doesn't seem to fit the mold in a couple of ways. The elements are
not spaced at all regularly. The spacing seems to vary around a bit.

I agree. It does look weird. However, having extra aluminum near the
antenna in the form of the other polarization, and getting sufficient
isolation between the two polarizations, is going to do strange things
to the design. Send me dimensions and I'll analyze it (time
permitting), like I did with the 2.4GHz MFJ1800 yagi:
http://802.11junk.com/jeffl/antennas/mfj1800/index.html

But more importantly, I've read that the director elements are
*insulated* from the support beam while these are all welded.

That's done so that the mounting boom does not become part of the
element length. Were it not insulated, half the circumference of the
boom would need to be added to the element lengths. Insulating the
elements also provides slightly fewer sidelobes and possibly (not
sure) better isolation between polarization. Looking at the patterns
on the data sheet, it looks much better than I would normally expect
from a single polarization yagi.

Obviously it works.

Assumption, the mother of all screwups. However, the data sheet does
seem to show that they actually made some measurements.

I'm getting about 6 dB stronger signal than before although
it's a bit hard to compare as the location changed and I measured about
a 3 dB gain with the old unit in that location.

But more importantly, with the signal rising by 6 dB, the reported
background noise also rose 6 dB. Isn't SNR what is important that the
antenna should have improved?

Yep. You want to maximize the SNR. Increasing both equally is about
what I would expect if your antenna were also pointed at other sources
of interference. The 900MHz smartmeters are a likely culprit. Plenty
of other possibilities. Can you move your new yagi around a little to
see if you can minimize the background noise?

This Yagi claims something like 20 or 25 degree beam while the old
antenna had a 60 degree beam.

A narrow beamwidth is good for reducing interference coming from off
axis interference sources. However, if the source of interference is
along the antenna axis, or in your case, within less than +/-10
degrees off axis, you can easily make things worse.

Got a 900MHz spectrum analyzer handy? Any of the USB RTL-SDR
(RTL2832U) dongles should do the trick, although a 900MHz RF amp will
probably be needed. Use it to see what you're dealing with.
http://www.rtl-sdr.com/?s=spectrum+analyzer



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

I had a WISP unit upgraded for better reception and they used a Yagi
antenna, at least I guess it's a Yagi. Here's a photo.

http://www.netwifiworks.com/images/a.../Yagi/yagi.png

This doesn't seem to fit the mold in a couple of ways. The elements are
not spaced at all regularly. The spacing seems to vary around a
bit.

Yagi-Uda antennas can be designed with all sorts of variations
in element spacing. There are complex interactions between the
element locations and lengths, leading to numerous tradeoffs
between maximum forward gain, bandwidth, front/back ratio, and
cleanliness of pattern (i.e. size and direction of side-lobes).

But more importantly, I've read that the director elements are
*insulated* from the support beam while these are all welded.

It's possible to build a Yagi with the director, driven, and reflector
elements either insulated from the boom, or connected to it
electrically... and not all elements have to be of the same style.

In general, if you connect an element to the boom, you do it right at
the element's center (so that the ground connection is balanced).
Connecting the element to the boom has the effect of "fattening" the
element where it passes through the boom, and makes it look "longer"
electrically than it is physically... so, in order to keep its
resonant frequency unchanged, you must shorten it somewhat.

Welding the elements to the beam makes good sense for physical
longevity... there are no insulators to age and crack in the sun and
weather, and no possibility of intermittent current leaks or arcing
(which can cause noise or intermodulation problems in higher-power
use).

But more importantly, with the signal rising by 6 dB, the reported
background noise also rose 6 dB.

That could indicate a couple of things. It could mean that the
predominent noise sources affecting you, are in the same direction as
the WISP transmitter... and so they're being boosted by the same
amount as the desired signal.

It could also indicate that your old antenna or feed-line was
electrically "lossy", and that you were losing some signal (and
received noise) to resistive losses.

On 1/27/2017 11:52 AM, Jeff Liebermann wrote:
On Fri, 27 Jan 2017 08:22:43 -0500, rickman wrote:

I had a WISP unit upgraded for better reception and they used a Yagi
antenna, at least I guess it's a Yagi. Here's a photo.
http://www.netwifiworks.com/images/a.../Yagi/yagi.png

Ok. That's an Ubiquiti AirMax AMY-9M16 900MHz antenna.
16dBi gain and dual simultaneous polarization (i.e. not switched):
https://www.ubnt.com/airmax/airmax-yagi-antenna/
https://dl.ubnt.com/datasheets/airmaxyagi/airMAX_900MHz_YAGI_Antenna.pdf
You need the dual polarization to get double the normal speed by using
2x2 MIMO streams, one per polarization.

I got a whole new setup. The old unit was one piece with what must have
been a panel antenna as the case was flat and broad. You can see what a
monster this one is. The beam is nearly three feet... no, I just
checked the data sheet and it around 4 feet long! It's not hugely
heavy, but to move it around I have to unbolt the mounting bracket and
it's a PITA while on a ladder.


This doesn't seem to fit the mold in a couple of ways. The elements are
not spaced at all regularly. The spacing seems to vary around a bit.

I agree. It does look weird. However, having extra aluminum near the
antenna in the form of the other polarization, and getting sufficient
isolation between the two polarizations, is going to do strange things
to the design. Send me dimensions and I'll analyze it (time
permitting), like I did with the 2.4GHz MFJ1800 yagi:
http://802.11junk.com/jeffl/antennas/mfj1800/index.html

If we get a warm day when I feel like messing with it I will. I spent
over an hour yesterday trying to optimize the orientation. I had
mounted a bracket under the deck thinking they would just move my
existing unit (NanoStation M900 Loco). I spent some time positioning
the unit and found a sweet spot that was two or three dB higher than the
surrounding area, next to a pole. Ok for this unit, but in the way for
the Yagi so it couldn't be aimed optimally. So I spent the time to
unbolt the bracket (everything was in the way of everything else so it
nearly all had to be dismounted) and move it to the other side of the
post. It can be pointed perfectly, but now it may be out of the sweet
spot so the numbers didn't change.

When the weather is better, I'll try moving it back to the sweet spot in
a way it can be aimed better. The old unit was easy to hold with your
hand and test. The Yagi is not so light and unwieldy, especially on a
ladder. I also want to move it to a less conspicuous spot. That will
be hard. I store kayaks under the deck mounted from pulleys.


But more importantly, I've read that the director elements are
*insulated* from the support beam while these are all welded.

That's done so that the mounting boom does not become part of the
element length. Were it not insulated, half the circumference of the
boom would need to be added to the element lengths. Insulating the
elements also provides slightly fewer sidelobes and possibly (not
sure) better isolation between polarization. Looking at the patterns
on the data sheet, it looks much better than I would normally expect
from a single polarization yagi.

Not sure if you understand me. This Yagi is *not* insulated. But
remember, it has 17 passive elements! It's not like they were just
fooling around. lol


Obviously it works.

Assumption, the mother of all screwups. However, the data sheet does
seem to show that they actually made some measurements.

I mean I'm getting some 6-7 dB better signal. Regardless of the SNR,
the receiver provides quality indexes that show a lower bit error rate
and higher overall throughput. That's why they put this up. It hasn't
improved my throughput so much, but it lowers the retransmits and
improves the utilization of their network.


I'm getting about 6 dB stronger signal than before although
it's a bit hard to compare as the location changed and I measured about
a 3 dB gain with the old unit in that location.

But more importantly, with the signal rising by 6 dB, the reported
background noise also rose 6 dB. Isn't SNR what is important that the
antenna should have improved?

Yep. You want to maximize the SNR. Increasing both equally is about
what I would expect if your antenna were also pointed at other sources
of interference. The 900MHz smartmeters are a likely culprit. Plenty
of other possibilities. Can you move your new yagi around a little to
see if you can minimize the background noise?

I'm not certain whether SNR or signal strength is most important. That
would depend on the noise factor of the receiver, no? I know in lower
frequencies the environmental noise is high enough the receiver noise
nearly doesn't matter. At higher frequencies I thought the limitation
was in the receiver front end. So until the noise gets to be high
enough that it approaches the receiver noise, it won't matter.


This Yagi claims something like 20 or 25 degree beam while the old
antenna had a 60 degree beam.

A narrow beamwidth is good for reducing interference coming from off
axis interference sources. However, if the source of interference is
along the antenna axis, or in your case, within less than +/-10
degrees off axis, you can easily make things worse.

Got a 900MHz spectrum analyzer handy? Any of the USB RTL-SDR
(RTL2832U) dongles should do the trick, although a 900MHz RF amp will
probably be needed. Use it to see what you're dealing with.
http://www.rtl-sdr.com/?s=spectrum+analyzer

What would a spectrum analyzer show me that would be useful. No, I
don't have one, but I could get one...

--

Rick C

On 1/27/2017 3:59 PM, rickman wrote:
On 1/27/2017 11:52 AM, Jeff Liebermann wrote:
On Fri, 27 Jan 2017 08:22:43 -0500, rickman wrote:

I had a WISP unit upgraded for better reception and they used a Yagi
antenna, at least I guess it's a Yagi. Here's a photo.
http://www.netwifiworks.com/images/a.../Yagi/yagi.png

Ok. That's an Ubiquiti AirMax AMY-9M16 900MHz antenna.
16dBi gain and dual simultaneous polarization (i.e. not switched):
https://www.ubnt.com/airmax/airmax-yagi-antenna/
https://dl.ubnt.com/datasheets/airmaxyagi/airMAX_900MHz_YAGI_Antenna.pdf

You need the dual polarization to get double the normal speed by using
2x2 MIMO streams, one per polarization.

I got a whole new setup. The old unit was one piece with what must have
been a panel antenna as the case was flat and broad. You can see what a
monster this one is. The beam is nearly three feet... no, I just
checked the data sheet and it around 4 feet long! It's not hugely
heavy, but to move it around I have to unbolt the mounting bracket and
it's a PITA while on a ladder.


This doesn't seem to fit the mold in a couple of ways. The elements are
not spaced at all regularly. The spacing seems to vary around a bit.

I agree. It does look weird. However, having extra aluminum near the
antenna in the form of the other polarization, and getting sufficient
isolation between the two polarizations, is going to do strange things
to the design. Send me dimensions and I'll analyze it (time
permitting), like I did with the 2.4GHz MFJ1800 yagi:
http://802.11junk.com/jeffl/antennas/mfj1800/index.html

If we get a warm day when I feel like messing with it I will. I spent
over an hour yesterday trying to optimize the orientation. I had
mounted a bracket under the deck thinking they would just move my
existing unit (NanoStation M900 Loco). I spent some time positioning
the unit and found a sweet spot that was two or three dB higher than the
surrounding area, next to a pole. Ok for this unit, but in the way for
the Yagi so it couldn't be aimed optimally. So I spent the time to
unbolt the bracket (everything was in the way of everything else so it
nearly all had to be dismounted) and move it to the other side of the
post. It can be pointed perfectly, but now it may be out of the sweet
spot so the numbers didn't change.

When the weather is better, I'll try moving it back to the sweet spot in
a way it can be aimed better. The old unit was easy to hold with your
hand and test. The Yagi is not so light and unwieldy, especially on a
ladder. I also want to move it to a less conspicuous spot. That will
be hard. I store kayaks under the deck mounted from pulleys.


But more importantly, I've read that the director elements are
*insulated* from the support beam while these are all welded.

That's done so that the mounting boom does not become part of the
element length. Were it not insulated, half the circumference of the
boom would need to be added to the element lengths. Insulating the
elements also provides slightly fewer sidelobes and possibly (not
sure) better isolation between polarization. Looking at the patterns
on the data sheet, it looks much better than I would normally expect
from a single polarization yagi.

Not sure if you understand me. This Yagi is *not* insulated. But
remember, it has 17 passive elements! It's not like they were just
fooling around. lol


Obviously it works.

Assumption, the mother of all screwups. However, the data sheet does
seem to show that they actually made some measurements.

I mean I'm getting some 6-7 dB better signal. Regardless of the SNR,
the receiver provides quality indexes that show a lower bit error rate
and higher overall throughput. That's why they put this up. It hasn't
improved my throughput so much, but it lowers the retransmits and
improves the utilization of their network.


I'm getting about 6 dB stronger signal than before although
it's a bit hard to compare as the location changed and I measured about
a 3 dB gain with the old unit in that location.

But more importantly, with the signal rising by 6 dB, the reported
background noise also rose 6 dB. Isn't SNR what is important that the
antenna should have improved?

Yep. You want to maximize the SNR. Increasing both equally is about
what I would expect if your antenna were also pointed at other sources
of interference. The 900MHz smartmeters are a likely culprit. Plenty
of other possibilities. Can you move your new yagi around a little to
see if you can minimize the background noise?

I'm not certain whether SNR or signal strength is most important. That
would depend on the noise factor of the receiver, no? I know in lower
frequencies the environmental noise is high enough the receiver noise
nearly doesn't matter. At higher frequencies I thought the limitation
was in the receiver front end. So until the noise gets to be high
enough that it approaches the receiver noise, it won't matter.


This Yagi claims something like 20 or 25 degree beam while the old
antenna had a 60 degree beam.

A narrow beamwidth is good for reducing interference coming from off
axis interference sources. However, if the source of interference is
along the antenna axis, or in your case, within less than +/-10
degrees off axis, you can easily make things worse.

Got a 900MHz spectrum analyzer handy? Any of the USB RTL-SDR
(RTL2832U) dongles should do the trick, although a 900MHz RF amp will
probably be needed. Use it to see what you're dealing with.
http://www.rtl-sdr.com/?s=spectrum+analyzer

What would a spectrum analyzer show me that would be useful. No, I
don't have one, but I could get one...

A specific question about the USB RTL-SDR. Would it and the software
allow me to get much detail in the LF band, specifically around 60 kHz?
That's an area I would like to do some work in.

--

Rick C

On Fri, 27 Jan 2017 16:13:30 -0500, rickman wrote:

A specific question about the USB RTL-SDR. Would it and the software
allow me to get much detail in the LF band, specifically around 60 kHz?
That's an area I would like to do some work in.

Y're guilty of topic drift. Give yourself a slap across the knuckles
with a wooden ruler.

The RTL2832 and R820T2 tuner covers 24 - 1766 Mhz. You can buy
upconverters but they typically bottom out at 100Khz.
http://www.ebay.com/itm/182423524669
http://www.ebay.com/sch/i.html?_nkw=rtl-dsp+upconverter
This is NOT the way to do WWVB.

The best way is to use a PC and a sound card. I learned the hard and
somewhat expensive way that an internal sound card is a great way to
analyze the spectrum of all the crap being generated inside the
computah. Therefore, I suggest an external USB sound card, that runs
at 192Kbits/sec or 384Kbits/sec.
http://www.ebay.com/sch/i.html?_nkw=192khz+sound+card+usb
I don't actually have one of these, but was able to play with one for
a few days with tolerable results.

There are examples of sound card VLF receivers on YouTube:
https://www.youtube.com/watch?v=L2W1x6Rb9hI
https://www.youtube.com/watch?v=EwxdZ0fY8fM
https://www.youtube.com/watch?v=UrJ77GiBNQw
https://www.youtube.com/watch?v=L2W1x6Rb9hI
https://www.youtube.com/watch?v=fKSOoZ2vhvo
SDR-sharp is the most common software used.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

In article , rickman wrote:

A specific question about the USB RTL-SDR. Would it and the software
allow me to get much detail in the LF band, specifically around 60 kHz?
That's an area I would like to do some work in.

Not directly. The tuner chips in these devices are designed to
operate at VHF and UHF.

The standard approach, when using these devices on HF, is to use an
upconverter to shift the signal up to somewhere around 120 MHz. You
could do the same with an LF signal, I imagine. Nooelec sells the
"Ham It Up" upconverter for this purpose; I don't know if its input
frequency response extends down to 60 kHz or not.

Some of the display-and-control software (e.g. GQRX on Linux) lets you
plug in a converter LO frequency number; it will then adjust the
frequency numbers on the display accordingly.

On Fri, 27 Jan 2017 14:45:25 -0800, Jeff Liebermann
wrote:

On Fri, 27 Jan 2017 16:13:30 -0500, rickman wrote:

A specific question about the USB RTL-SDR. Would it and the software
allow me to get much detail in the LF band, specifically around 60 kHz?
That's an area I would like to do some work in.

Y're guilty of topic drift. Give yourself a slap across the knuckles
with a wooden ruler.

+1 I am not aware of too many 60kHz yagi antennas

On 1/27/2017 7:06 PM, Pat wrote:
On Fri, 27 Jan 2017 14:45:25 -0800, Jeff Liebermann
wrote:

On Fri, 27 Jan 2017 16:13:30 -0500, rickman wrote:

A specific question about the USB RTL-SDR. Would it and the software
allow me to get much detail in the LF band, specifically around 60 kHz?
That's an area I would like to do some work in.

Y're guilty of topic drift. Give yourself a slap across the knuckles
with a wooden ruler.

+1 I am not aware of too many 60kHz yagi antennas

You don't notice them sort of like not noticing the galactic super
cluster we are in.

--

Rick C