bowtie panel antenna...

[whit3rd]

On Thursday, January 6, 2022 at 7:47:48 AM UTC-8, sidw...@gmail.com wrote:

I want to setup a bowtie panel antenna to receive UHF Terrestrial TV transmissions in my area. I live between two stations approximately 180 degrees from each other.
Is it practical to build and setup a Bow-tie Panel Antenna and leave off the reflector to cause the antenna to receive signals front and back ?

Sure; a dipole antenna has a figure-eight reception pattern, you\'d be aiming a lobe at each of the
sources.

> How much does the reflector add to the gain ?

Usually, a reflector removes one lobe, replacing it with a stronger \'other\' lobe (but
this is all frequency-dependent, the reflector spacing can be important). That\'d be 3 dB gain.
There\'s usually a broad range of acceptable sensitivity for an antenna, the \'extra gain\'\' isn\'t crucial.

 

[Ralph Mowery]

In article <63ea7b65-0507-4902-b23a-6a30f61c7adan@googlegroups.com>,
pallison49@gmail.com says...

I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.


** Yep - one type is called a \"collinear \" antenna.

https://en.wikipedia.org/wiki/Collinear_antenna_array

The one caveat is the \"pattern\" is only being considered in the horizontal plane.
Standard practice for any broadcast antenna set up.

https://www.everythingrf.com/community/what-is-a-collinear-antenna

The horizontal pattern stays the same, but the vertical pattern changes.

If the antenna is somethat higher or lower than another antenna even
the horizontal pattern will seem to change as one antenna over shoots
the other.

 

[Phil Allison]

Ralph Mowery wrote:
==================

I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.


** Yep - one type is called a \"collinear \" antenna.

https://en.wikipedia.org/wiki/Collinear_antenna_array

The one caveat is the \"pattern\" is only being considered in the horizontal plane.
Standard practice for any broadcast antenna set up.


The collinear modifies the horizontal patern by taking some signal from
the vertical.

** Did you read my caveat comment at all ?

> Pattern still modified for gain.

** But not relevant to the original question re BROADCAST reception.

Context, context, context, context !!!!!!.


....... Phil

 

[whit3rd]

On Thursday, January 6, 2022 at 1:42:33 PM UTC-8, Ralph Mowery wrote:

In article <e1metglue8alf2jal...@4ax.com>,
jlarkin@highland_atwork_technology.com says...

I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.



Then you have exceeded the laws of antennas.


Care to tell a way to do that in any prctical antenna ?

I think he\'s talking about a wollenweber array of dipoles, with preamplification
then phase-shifting and combination afterward. That worked with lots of operators
trying combinations, for directing fighter craft against bombers, around (for instance)
Berlin, 1943. The linkage used by wool thread spinners to gather their product
is a \'wool-weaver\' which is what the dipole array must have suggested.

Alert operators can do the tuning dynamically (those fighter craft MOVED).

 

[Phil Allison]

John Larkin wrote:
===============

I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.


Then you have exceeded the laws of antennas.
Laws of antennas? Or folklore?

** Smartarse.

Care to tell a way to do that in any prctical antenna ?

One obvious way: run a feeder from N antennas to a central point.
There, run each signal into a receiver. Combine the receiver outputs.
The RF phase information is lost.

** Loud ring goes off !!
That idea is *outside* the parameters of the question re:

\" signals from multiple dipoles can be combined \"

There\'s probably a passive way to combine an array of dipoles but keep
the same far-field pattern.

** But JL has no idea nor cares a hoot what it is.



..... Phil

 

[Jan Panteltje]

On a sunny day (Thu, 06 Jan 2022 15:32:16 -0800) it happened John Larkin
<jlarkin@highland_atwork_technology.com> wrote in
<4fuetgtesrbtt5on9kl9qv9kb182sv2gps@4ax.com>:

On Thu, 6 Jan 2022 16:42:26 -0500, Ralph Mowery
rmowery42@charter.net> wrote:

In article <e1metglue8alf2jalkt3nm3f7at3lmb3kp@4ax.com>,
jlarkin@highland_atwork_technology.com says...

I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.




Then you have exceeded the laws of antennas.

Laws of antennas? Or folklore?



Care to tell a way to do that in any prctical antenna ?

One obvious way: run a feeder from N antennas to a central point.
There, run each signal into a receiver. Combine the receiver outputs.
The RF phase information is lost.

There\'s probably a passive way to combine an array of dipoles but keep
the same far-field pattern.

One important thing to take into account is all the cable losses.
The reason mine works so well is
1) length cable only 2 meters
2) antenna is about 1/4 wavelength
3) no connector losses
4) indoors fields and phases combine and all sort of wave patterns exist, use a local one that is strong.
5) no pre-amps no power needed.

 

[John Walliker]

On Thursday, 6 January 2022 at 23:49:00 UTC, palli...@gmail.com wrote:

John Larkin wrote:
===============

I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.


Then you have exceeded the laws of antennas.
Laws of antennas? Or folklore?
** Smartarse.
Care to tell a way to do that in any prctical antenna ?

One obvious way: run a feeder from N antennas to a central point.
There, run each signal into a receiver. Combine the receiver outputs.
The RF phase information is lost.

** Loud ring goes off !!
That idea is *outside* the parameters of the question re:
\" signals from multiple dipoles can be combined \"
There\'s probably a passive way to combine an array of dipoles but keep
the same far-field pattern.
** But JL has no idea nor cares a hoot what it is.
.... Phil

Passive combining of multiple antennas will always change the directional
response in some way.
Combining the outputs of multiple receivers to improve performance without
modifying the directional response is standard practice and was first done
about 100 years ago.

John

 

[amdx]

On 1/6/2022 5:04 PM, Ralph Mowery wrote:

In article <d2setgldhnfr1v7h31h9gl61jimta3otfi@4ax.com>,
joegwinn@comcast.net says...
I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.



Then you have exceeded the laws of antennas.


Care to tell a way to do that in any prctical antenna ?
It\'s widely done in radar systems. It\'s called spoiling the beam.
This is typically done to the transmit beam, so multiple overlapping
receive beams can be used per TX pulse.

All it takes is some random detuning of the drive phases at the
various elements.

Joe Gwinn


The antenna uses around 1000 to 2000 dipoles. The beam width is about 1
or 2 degrees. The antennas are phased electrically so you sweep that
small segment over a larger area. It replaces the mechanical need to
rotate the whole antenna.

So with the beam width being so small instead of 180 degrees of a dipole
you have modified the pattern of a single dipole.

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[amdx]

On 1/7/2022 5:31 AM, John Walliker wrote:

On Thursday, 6 January 2022 at 23:49:00 UTC, palli...@gmail.com wrote:
John Larkin wrote:
===============
I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.


Then you have exceeded the laws of antennas.
Laws of antennas? Or folklore?
** Smartarse.
Care to tell a way to do that in any prctical antenna ?
One obvious way: run a feeder from N antennas to a central point.
There, run each signal into a receiver. Combine the receiver outputs.
The RF phase information is lost.

** Loud ring goes off !!
That idea is *outside* the parameters of the question re:
\" signals from multiple dipoles can be combined\"
There\'s probably a passive way to combine an array of dipoles but keep
the same far-field pattern.
** But JL has no idea nor cares a hoot what it is.
.... Phil
Passive combining of multiple antennas will always change the directional
response in some way.
Combining the outputs of multiple receivers to improve performance without
modifying the directional response is standard practice and was first done
about 100 years ago.

John

No one has mentioned that this constructive addition, needs to work over
470MHz to 698 MHz, and if you happen to have a VHF station,

 it might need to work down to 54MHz.

                                      Mikek


--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[server]

On Fri, 7 Jan 2022 09:15:12 -0600, amdx <amdx@knology.net> wrote:

On 1/7/2022 5:31 AM, John Walliker wrote:
On Thursday, 6 January 2022 at 23:49:00 UTC, palli...@gmail.com wrote:
John Larkin wrote:
===============
I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.


Then you have exceeded the laws of antennas.
Laws of antennas? Or folklore?
** Smartarse.
Care to tell a way to do that in any prctical antenna ?
One obvious way: run a feeder from N antennas to a central point.
There, run each signal into a receiver. Combine the receiver outputs.
The RF phase information is lost.

** Loud ring goes off !!
That idea is *outside* the parameters of the question re:
\" signals from multiple dipoles can be combined\"
There\'s probably a passive way to combine an array of dipoles but keep
the same far-field pattern.
** But JL has no idea nor cares a hoot what it is.
.... Phil
Passive combining of multiple antennas will always change the directional
response in some way.
Combining the outputs of multiple receivers to improve performance without
modifying the directional response is standard practice and was first done
about 100 years ago.

John

No one has mentioned that this constructive addition, needs to work over
470MHz to 698 MHz, and if you happen to have a VHF station,

 it might need to work down to 54MHz.

                                      Mikek

Given a defense-sized budget, one could digitize each antenna signal
and combine them digitally. Add phase shifts as needed. That\'s a
project but it\'s not totally crazy, with modern multichannel ADCs and
an FPGA.

At one frequency, move the dipoles around to tweak the pattern.

Or switch in some delays with relays or something. That could be cool.
Try every combination for max signal strength.



--

I yam what I yam - Popeye

 

[Phil Hobbs]

John Walliker wrote:

On Thursday, 6 January 2022 at 23:49:00 UTC, palli...@gmail.com wrote:
John Larkin wrote:
===============

I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.


Then you have exceeded the laws of antennas.
Laws of antennas? Or folklore?
** Smartarse.
Care to tell a way to do that in any prctical antenna ?

One obvious way: run a feeder from N antennas to a central point.
There, run each signal into a receiver. Combine the receiver outputs.
The RF phase information is lost.

** Loud ring goes off !!
That idea is *outside* the parameters of the question re:
\" signals from multiple dipoles can be combined\"
There\'s probably a passive way to combine an array of dipoles but keep
the same far-field pattern.
** But JL has no idea nor cares a hoot what it is.
.... Phil

Passive combining of multiple antennas will always change the directional
response in some way.
Combining the outputs of multiple receivers to improve performance without
modifying the directional response is standard practice and was first done
about 100 years ago.

You only win SNR like the square root when you combine the demodulated
outputs, whereas you win linearly with coherent combining.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Jan Panteltje]

On a sunny day (Fri, 07 Jan 2022 08:06:01 -0800) it happened
jlarkin@highlandsniptechnology.com wrote in
<8rogtg9p9akf3ltubtduokn0bp4vmtm9vf@4ax.com>:

Given a defense-sized budget, one could digitize each antenna signal
and combine them digitally. Add phase shifts as needed. That\'s a
project but it\'s not totally crazy, with modern multichannel ADCs and
an FPGA.

Not sure there is much point in digitizing 2 signals that are mostly in the noise.
You want an as large as possible signal before processing?

It is all phased arrays in the new Russian radars,
and in Elon\'s sat receivers.
https://hackaday.com/2020/11/25/literally-tearing-apart-a-spacex-starlink-antenna/
Look at that board!
It can direct the tx beam and rx direction in any angle.
Same for modern flat satellite dishes

 

[ke...@kjwdesigns.com]

On Friday, 7 January 2022 at 08:06:10 UTC-8, jla...@highlandsniptechnology.com wrote:
....

Given a defense-sized budget, one could digitize each antenna signal
and combine them digitally. Add phase shifts as needed. That\'s a
project but it\'s not totally crazy, with modern multichannel ADCs and
an FPGA.

At one frequency, move the dipoles around to tweak the pattern.

Or switch in some delays with relays or something. That could be cool.
Try every combination for max signal strength.
....

That\'s how most automotive (and many military) radars work. You can do four receivers for $25 and cascade up to four of the devices together to give 16 receivers (and 12 transmitters)

https://www.ti.com/product/AWR1843

By doing appropriate processing (mainly multiple axes of FFTs) the equivalent of a wide field of view antenna is created but with the gain of a narrow beam width.

kw

 

[John Walliker]

On Friday, 7 January 2022 at 16:23:28 UTC, Phil Hobbs wrote:

Passive combining of multiple antennas will always change the directional
response in some way.
Combining the outputs of multiple receivers to improve performance without
modifying the directional response is standard practice and was first done
about 100 years ago.
You only win SNR like the square root when you combine the demodulated
outputs, whereas you win linearly with coherent combining.

Yes, but the reason for combining receiver outputs is often to overcome fading
rather than just to improve snr. In that case, the final output will usually be the
\"best\" of the multiple receiver outputs or a weighted combination rather than
just a linear sum.

John

 

[Jasen Betts]

On 2022-01-06, John Larkin <jlarkin@highland_atwork_technology.com> wrote:

On Thu, 6 Jan 2022 14:13:52 -0500, Ralph Mowery
rmowery42@charter.net> wrote:

In article <om9etg5bfjcn9ngm3piu4o1q1324tlanj8@4ax.com>,
jlarkin@highlandsniptechnology.com says...

If a dipole gathers a milliwatt, another dipole some modest distance
away will gather another milliwatt. Seems to me that the powers can be
added without altering the far-field patterns.





That is true about gain if the spacing and impedance matching are
correct, but the pattern still changes. If the dipoles are too close or
too far apart the phasing is not correct and the signals cancel.
Instead of gain, the pattern breaks up and you may get no signal at all
or a very small signal. They still modify the pattern in some way.

If and only if the spacing is correct two dipoles will double the
signal, not counting on a small loss of interconnecting cables . To
double that you need 4 dipoles for 8, to double that you need 16 dipoles
all phased correctly. With each set of dipoles the beam will narrow so
you have to aim the antenna closer to the station.

I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.

You\'re mistaken. if you build a phased-array antenna you get increased
directionality (so a tighter far field pattern) and a stronger signal.

Gain and directionality are inextricably linked for passive antannnae.

If you have some way to connect multiple antennae without creating a
phased array I\'d like to hear about it.

--
Jasen.

 

[Phil Allison]

Jasen Bullshits wrote:

====================

I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.

You\'re mistaken. if you build a phased-array antenna you get increased
directionality (so a tighter far field pattern) and a stronger signal.

Gain and directionality are inextricably linked for passive antannnae.

** ROTFL - insects have \"antennae\" !!!

Worse than that idiocy, is that everyone but me has arrogantly ignored the OP\'s context.
Colossal pedant Ralph Mowery kicked it off and all the sheep here followed.

For fixed location antennas, only the *horizontal * pattern ever matters and is the only one speced.
So \"directionality\" = horizontal pattern.

FFS when are you going to learn that queries posted here are NOT fucking exam questions.


( except when some wanker sneakily posts one they need to answer)



...... Phil

 

[John Walliker]

On Saturday, 8 January 2022 at 02:05:53 UTC, palli...@gmail.com wrote:

For fixed location antennas, only the *horizontal * pattern ever matters and is the only one speced.
So \"directionality\" = horizontal pattern.

Almost every antenna data sheet I have looked at gives horizontal and vertical radiation
patterns. For TV antennas - which are relevant to the OP\'s question - both are needed
because the manufacturer will not know whether the transmissions to be received
are horizontally or vertically polarised and therefore will not know which orientation
of the antenna is horizontal when installed. Around here, for example, there are two
TV transmitters within range and one is horizontally polarised while the other is
vertically polarised.
Mobile phone base station antennas definitely have vertical as well as horizontal
radiation patterns specified. Both are important.

John

 

[Phil Allison]

John Walliker wrote:
=================
Wot a wanking IDIOT
--------------------------------

palli...@gmail.com wrote:

For fixed location antennas, only the *horizontal * pattern ever matters and is the only one speced.
So \"directionality\" = horizontal pattern.

Almost every antenna data sheet I have looked at gives horizontal and vertical radiation
patterns.

** Fuck knows what shit data YOU look at.

When intended for broadcast TV reception, it is just as I stated.

For TV antennas - which are relevant to the OP\'s question - both are needed
because the manufacturer will not know whether the transmissions to be received
are horizontally or vertically polarised .....

** Total crap.

In the places cases where TV signals are vertically polarised, the exact same antennas are mounted at 90 degrees.
Many TV and FM transmitters use circular polarisation that work fine, both ways.

Crawl back under your rock.



....... Phil

 

[John Walliker]

On Saturday, 8 January 2022 at 11:43:14 UTC, palli...@gmail.com wrote:

John Walliker wrote:
=================
Wot a wanking IDIOT
--------------------------------
palli...@gmail.com wrote:

For fixed location antennas, only the *horizontal * pattern ever matters and is the only one speced.
So \"directionality\" = horizontal pattern.

Almost every antenna data sheet I have looked at gives horizontal and vertical radiation
patterns.
** Fuck knows what shit data YOU look at.

Here are some examples of the data sheets I look at for a few different antenna types:
amphenolprocom.com/media/pdfdocs/s-m4-490.en-GB.pdf
amphenolprocom.com/media/pdfdocs/lpu-r.en-GB.pdf
amphenolprocom.com/media/pdfdocs/7042440.en-GB.pdf
amphenolprocom.com/media/pdfdocs/7050108.en-GB.pdf

They all have E-plane and H-plane polar response plots.

> When intended for broadcast TV reception, it is just as I stated.

The second link above is for a TV antenna. It has E and H-plane plots.
As it happens, they are almost identical, but that does not apply to
some of the other types.

For TV antennas - which are relevant to the OP\'s question - both are needed
because the manufacturer will not know whether the transmissions to be received
are horizontally or vertically polarised .....

** Total crap.

In the places cases where TV signals are vertically polarised, the exact same antennas are mounted at 90 degrees.

That is exactly what I said.

> Many TV and FM transmitters use circular polarisation that work fine, both ways.

FM yes, TV seldom.

> Crawl back under your rock.

I\'ll be happy to.

John

 

[server]

On Sat, 8 Jan 2022 01:11:28 -0000 (UTC), Jasen Betts
<usenet@revmaps.no-ip.org> wrote:

On 2022-01-06, John Larkin <jlarkin@highland_atwork_technology.com> wrote:
On Thu, 6 Jan 2022 14:13:52 -0500, Ralph Mowery
rmowery42@charter.net> wrote:

In article <om9etg5bfjcn9ngm3piu4o1q1324tlanj8@4ax.com>,
jlarkin@highlandsniptechnology.com says...

If a dipole gathers a milliwatt, another dipole some modest distance
away will gather another milliwatt. Seems to me that the powers can be
added without altering the far-field patterns.





That is true about gain if the spacing and impedance matching are
correct, but the pattern still changes. If the dipoles are too close or
too far apart the phasing is not correct and the signals cancel.
Instead of gain, the pattern breaks up and you may get no signal at all
or a very small signal. They still modify the pattern in some way.

If and only if the spacing is correct two dipoles will double the
signal, not counting on a small loss of interconnecting cables . To
double that you need 4 dipoles for 8, to double that you need 16 dipoles
all phased correctly. With each set of dipoles the beam will narrow so
you have to aim the antenna closer to the station.

I think signals from multiple dipoles can be combined without altering
the far-field pattern. I can think of several ways to do that.

You\'re mistaken. if you build a phased-array antenna you get increased
directionality (so a tighter far field pattern) and a stronger signal.

Gain and directionality are inextricably linked for passive antannnae.

If you have some way to connect multiple antennae without creating a
phased array I\'d like to hear about it.

It\'s easy in the plane of a bunch of dipoles: for horizontal dipoles,
stack them verticaly on a pole and connect in parallel with equal
length feeders. The horizontal far-field pattern doesn\'t change. I
think Chain Home did that.

There may be a way to fix the vertical axis, but in a terrestrial
situation one doesn\'t usually care about that.



--

I yam what I yam - Popeye