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Hi Team,

I try to measure VSWR of the following antenna:



NanoVNA is calibrated to antenna side of RG58. I had to use N-F/SMA-M +
SMA-F/SMA-F adapters in front of SOL kit, but tried to subtract it with
edelay.

On the product page someone wrote "Swr on 2m is 1.5 to 1.7.1 on 446 it's
1.0.1". I can't seem to get even close, something wrong with me setup. Any
suggestions what am I missing?

Best Regards,
MarcoFI

one has to consider the environment, not discussed prior in this thread. If
there were any metal or other electrically conductive material near the
antenna when tested that could be a possible cause for the difference in
measurement data and that which is published.
*Clyde K. Spencer*



On Wed, Aug 2, 2023 at 11:09?AM Jim via groups.io <teotwaki=
[email protected]> wrote:

This antenna is related to what antenna design literature calls a
“产颈肠辞苍颈肠补濒“

- - Biconical antennas have dipole characteristics. The double cone
elements structure contributes to their wider bandwidth. The antenna
becomes more broadband as the cone angle increases. - -

Search on that name for design and results discussions

Jim

Maybe the matching at 70cm band is better because the coaxial cable losses
are higher there ?

If I remember right there was a considerable length of lossy RG58 used
during the measurements ?

Kind regards

Matthias

www.dd1us.de


-----Ursprüngliche Nachricht-----
Von: [email protected] <[email protected]> Im Auftrag von
W0LEV via groups.io
Gesendet: Donnerstag, 3. August 2023 19:38
An: [email protected]
Betreff: Re: [nanovna-users] Double Discone VSWR

I checked this antenna on the Moonraker site, specifically amateur radio
antennas. It's rated for ONLY the 70-CM BAND.
[image: image.png]
Sure, it will receive over a wide band with relatively poor efficiency,
but for transmit - low SWR - it's rated for only 130 to 175 MHz and 410 to
475 MHz. This is pretty much what the SWR sweeps have shown with the
exception of the 2-meter and aircraft bands. The SWR sweeps that have been
shown in this thread exhibit low SWR ONLY in the 70-CM BAND. That's what
the spec's show!

Further, the claimed 5.5 dBi over a standard discone is bogus. A standard
discone radiates (and receives) pretty much like a 1/4-wavelength over an
image plane. 5.5 dBi over this is not realizable. And I can imagine, if
it were, that figure would apply only to 70-cm.

Dave - W?LEV




On Thu, Aug 3, 2023 at 4:19?AM Bob Ecclestone VK2ZRE <becclest@...

wrote:

I am surprised some folk on this group have rubbished Moonraker Antennas.
I know Moonraker HF antennas are used on some Australian Navy ships,
so I don't think they are really "Dollar Shop junk."
I don't have any connection with either Moonraker or the the
Australian Navy.
So perhaps those with complaints may need to examine their
installation practices.
Or contact Moonraker or their dealer for support.
Just my 2c worth.

Cheers...Bob VK2ZRE


On 3/08/2023 2:33 am, Clyde Spencer wrote:

one has to consider the environment, not discussed prior in this

thread.

If

there were any metal or other electrically conductive material near
the antenna when tested that could be a possible cause for the
difference in measurement data and that which is published.
*Clyde K. Spencer*



On Wed, Aug 2, 2023 at 11:09?AM Jim via groups.io <teotwaki=
[email protected]> wrote:

This antenna is related to what antenna design literature calls a
“产颈肠辞苍颈肠补濒“

- - Biconical antennas have dipole characteristics. The double cone
elements structure contributes to their wider bandwidth. The
antenna becomes more broadband as the cone angle increases. - -

Search on that name for design and results discussions

Jim

--

*Dave - W?LEV*


--
Dave - W?LEV

Maybe the matching at 70cm band is better because the coaxial cable
losses are higher there ?

If I remember right there was a considerable length of lossy RG58 used
during the measurements ?

Kind regards

Matthias

www.dd1us.de


-----Ursprüngliche Nachricht-----
Von: [email protected] <[email protected]> Im Auftrag von
W0LEV via groups.io
Gesendet: Donnerstag, 3. August 2023 19:38
An: [email protected]
Betreff: Re: [nanovna-users] Double Discone VSWR

I checked this antenna on the Moonraker site, specifically amateur
radio antennas. It's rated for ONLY the 70-CM BAND.
[image: image.png]
Sure, it will receive over a wide band with relatively poor
efficiency, but for transmit - low SWR - it's rated for only 130 to
175 MHz and 410 to
475 MHz. This is pretty much what the SWR sweeps have shown with the
exception of the 2-meter and aircraft bands. The SWR sweeps that have
been shown in this thread exhibit low SWR ONLY in the 70-CM BAND.
That's what the spec's show!

Further, the claimed 5.5 dBi over a standard discone is bogus. A
standard discone radiates (and receives) pretty much like a
1/4-wavelength over an image plane. 5.5 dBi over this is not
realizable. And I can imagine, if it were, that figure would apply only to 70-cm.

Dave - W?LEV




On Thu, Aug 3, 2023 at 4:19?AM Bob Ecclestone VK2ZRE
<becclest@...

wrote:

I am surprised some folk on this group have rubbished Moonraker Antennas.
I know Moonraker HF antennas are used on some Australian Navy ships,
so I don't think they are really "Dollar Shop junk."
I don't have any connection with either Moonraker or the the
Australian Navy.
So perhaps those with complaints may need to examine their
installation practices.
Or contact Moonraker or their dealer for support.
Just my 2c worth.

Cheers...Bob VK2ZRE


On 3/08/2023 2:33 am, Clyde Spencer wrote:

one has to consider the environment, not discussed prior in this

thread.

If

there were any metal or other electrically conductive material
near the antenna when tested that could be a possible cause for
the difference in measurement data and that which is published.
*Clyde K. Spencer*



On Wed, Aug 2, 2023 at 11:09?AM Jim via groups.io <teotwaki=
[email protected]> wrote:

This antenna is related to what antenna design literature calls a
“产颈肠辞苍颈肠补濒“

- - Biconical antennas have dipole characteristics. The double
cone elements structure contributes to their wider bandwidth. The
antenna becomes more broadband as the cone angle increases. - -

Search on that name for design and results discussions

Jim

--

*Dave - W?LEV*


--
Dave - W?LEV

I agree Dave, the losses should increase steadily with increasing
frequency.

However the measured return loss will be higher when measuring with a
lossy cable,
i.e. the real return loss will be worse that what the measurement shows.

Kind regards

Matthias

www.dd1us.de


-----Ursprüngliche Nachricht-----
Von: [email protected] <[email protected]> Im Auftrag von
W0LEV via groups.io
Gesendet: Donnerstag, 3. August 2023 19:58
An: [email protected]
Betreff: Re: [nanovna-users] Double Discone VSWR

No. The SWR plots shown on this thread show a dip in SWR centered on
70-cm. If it were due to coax loss, the losses would continue above
70-cm. They don't.

Dave - W?LEV

On Thu, Aug 3, 2023 at 5:54?PM Matthias <matthias.bopp@...> wrote:

Maybe the matching at 70cm band is better because the coaxial cable
losses are higher there ?

If I remember right there was a considerable length of lossy RG58 used
during the measurements ?

Kind regards

Matthias

www.dd1us.de


-----Ursprüngliche Nachricht-----
Von: [email protected] <[email protected]> Im Auftrag von
W0LEV via groups.io
Gesendet: Donnerstag, 3. August 2023 19:38
An: [email protected]
Betreff: Re: [nanovna-users] Double Discone VSWR

I checked this antenna on the Moonraker site, specifically amateur
radio antennas. It's rated for ONLY the 70-CM BAND.
[image: image.png]
Sure, it will receive over a wide band with relatively poor
efficiency, but for transmit - low SWR - it's rated for only 130 to
175 MHz and 410 to
475 MHz. This is pretty much what the SWR sweeps have shown with the
exception of the 2-meter and aircraft bands. The SWR sweeps that have
been shown in this thread exhibit low SWR ONLY in the 70-CM BAND.
That's what the spec's show!

Further, the claimed 5.5 dBi over a standard discone is bogus. A
standard discone radiates (and receives) pretty much like a
1/4-wavelength over an image plane. 5.5 dBi over this is not
realizable. And I can imagine, if it were, that figure would apply only

to 70-cm.

Dave - W?LEV




On Thu, Aug 3, 2023 at 4:19?AM Bob Ecclestone VK2ZRE
<becclest@...

wrote:

I am surprised some folk on this group have rubbished Moonraker

Antennas.

I know Moonraker HF antennas are used on some Australian Navy ships,
so I don't think they are really "Dollar Shop junk."
I don't have any connection with either Moonraker or the the
Australian Navy.
So perhaps those with complaints may need to examine their
installation practices.
Or contact Moonraker or their dealer for support.
Just my 2c worth.

Cheers...Bob VK2ZRE


On 3/08/2023 2:33 am, Clyde Spencer wrote:

one has to consider the environment, not discussed prior in this

thread.

If

there were any metal or other electrically conductive material
near the antenna when tested that could be a possible cause for
the difference in measurement data and that which is published.
*Clyde K. Spencer*



On Wed, Aug 2, 2023 at 11:09?AM Jim via groups.io <teotwaki=
[email protected]> wrote:

This antenna is related to what antenna design literature calls a
“产颈肠辞苍颈肠补濒“

- - Biconical antennas have dipole characteristics. The double
cone elements structure contributes to their wider bandwidth. The
antenna becomes more broadband as the cone angle increases. - -

Search on that name for design and results discussions

Jim

--

*Dave - W?LEV*


--
Dave - W?LEV

--

*Dave - W?LEV*


--
Dave - W?LEV

Over the years I have built several biconical and discone antennas. These
antennas do have a wider bandwidth than a standard dipole, and also a lower
impedance, but they are far from covering several bands and everything in
between, which is what some people claim.

For example, I made a biconical antenna to use as the driven element of a
digital TV antenna, operating in front of a large reflector. I used a 30°
angle, solid cones, properly trimming the length, and this gave just the
required 500-700MHz range between the 3:1 SWR points. A wider angle lowers
the impedance too far below 50?.

I have read that a slightly larger bandwidth can be obtained by making a
full wave biconical, and use a very wide angle, wider than 90°. It should
also give some gain. The impedance of a full wave dipole is very high, but
making one this fat, it comes down into a usable range. But my practical
tests turned out not very brilliant. I never got a usable match to a coax
cable.

Planar phased array antennas often use sets of fat full wave dipols, with
a matching circuit consisting of wuarter wave sections, all made on a
single PCB. These seem to work, at least some of them, but only over a
pretty limited bandwidth.

A biconical antenna is a balanced antenna. When feeding it with a coax
cable, a suitable balun should be used, even when the antenna is placed
vertically. Without a balun, running the coax (and a metal mast!) inside
the lower element should be better than placing them outside, but there
will always be interaction.

A discone is also closer to a balanced than an unbalanced antenna!

Dissolving the solid cones and discs into sets of spokes, the behavior
changes very much! Some authors claim that using 8 spokes is the same as a
solid cone, but this is not true. Just try it!

In any case, the claim that a discone or biconical antenna is almost a
DC-to-daylight antenna is simply not true, even in RX, let alone in TX!
Which of course doesn't hinder manufacturers to keep claiming this, and
book authors to keep copying and pasting that claim without having ever
built such an antenna themselves.

Manfred

And what's more with the discone, both the elevation angle of radiation
(and reception) and polarization change with frequency. It may look good
on the Smith chart, but in reality, neither the discone and the bicone are
very good antennas, even compared to a dipole or LPDA.

In the past, we have used the bicone in EMC testing for regulatory
purposes. However, when commercially available LPDAs with extended
frequency ranges and methods of calibrating the antenna factor hit the
world, the bicone was rapidly abandoned. Even in most cases where I used
the bicone for regulatory testing, we put it to bed ar roughly 300 MHz. It
is not a particularly "good" antenna.

Dave - W?LEV

On Thu, Aug 3, 2023 at 9:00?PM Manfred Mornhinweg <manfred@...>
wrote:

Over the years I have built several biconical and discone antennas. These
antennas do have a wider bandwidth than a standard dipole, and also a

lower

impedance, but they are far from covering several bands and everything in
between, which is what some people claim.

For example, I made a biconical antenna to use as the driven element of a
digital TV antenna, operating in front of a large reflector. I used a

30°

angle, solid cones, properly trimming the length, and this gave just the
required 500-700MHz range between the 3:1 SWR points. A wider angle

lowers

the impedance too far below 50?.

I have read that a slightly larger bandwidth can be obtained by making a
full wave biconical, and use a very wide angle, wider than 90°. It should
also give some gain. The impedance of a full wave dipole is very high,

but

making one this fat, it comes down into a usable range. But my practical
tests turned out not very brilliant. I never got a usable match to a coax
cable.

Planar phased array antennas often use sets of fat full wave dipols, with
a matching circuit consisting of wuarter wave sections, all made on a
single PCB. These seem to work, at least some of them, but only over a
pretty limited bandwidth.

A biconical antenna is a balanced antenna. When feeding it with a coax
cable, a suitable balun should be used, even when the antenna is placed
vertically. Without a balun, running the coax (and a metal mast!) inside
the lower element should be better than placing them outside, but there
will always be interaction.

A discone is also closer to a balanced than an unbalanced antenna!

Dissolving the solid cones and discs into sets of spokes, the behavior
changes very much! Some authors claim that using 8 spokes is the same as

a

solid cone, but this is not true. Just try it!

In any case, the claim that a discone or biconical antenna is almost a
DC-to-daylight antenna is simply not true, even in RX, let alone in TX!
Which of course doesn't hinder manufacturers to keep claiming this, and
book authors to keep copying and pasting that claim without having ever
built such an antenna themselves.

Manfred

--

*Dave - W?LEV*


--
Dave - W?LEV

Put not your faith in Amateur Radio dealers…they are there to make a
living, not friends.
Further more, the gain figures are generally in the minds of the
advertising managers, rather than the designers.

On Thu, 3 Aug 2023 at 22:18, W0LEV <davearea51a@...> wrote:

And what's more with the discone, both the elevation angle of radiation
(and reception) and polarization change with frequency. It may look good
on the Smith chart, but in reality, neither the discone and the bicone

are

very good antennas, even compared to a dipole or LPDA.

In the past, we have used the bicone in EMC testing for regulatory
purposes. However, when commercially available LPDAs with extended
frequency ranges and methods of calibrating the antenna factor hit the
world, the bicone was rapidly abandoned. Even in most cases where I used
the bicone for regulatory testing, we put it to bed ar roughly 300 MHz.

It

is not a particularly "good" antenna.

Dave - W?LEV

On Thu, Aug 3, 2023 at 9:00?PM Manfred Mornhinweg <manfred@...>
wrote:

Over the years I have built several biconical and discone antennas.

These

antennas do have a wider bandwidth than a standard dipole, and also a

lower

impedance, but they are far from covering several bands and everything

in

between, which is what some people claim.

For example, I made a biconical antenna to use as the driven element

of a

digital TV antenna, operating in front of a large reflector. I used a

30°

angle, solid cones, properly trimming the length, and this gave just

the

required 500-700MHz range between the 3:1 SWR points. A wider angle

lowers

the impedance too far below 50?.

I have read that a slightly larger bandwidth can be obtained by making

a

full wave biconical, and use a very wide angle, wider than 90°. It

should

also give some gain. The impedance of a full wave dipole is very high,

but

making one this fat, it comes down into a usable range. But my

practical

tests turned out not very brilliant. I never got a usable match to a

coax

cable.

Planar phased array antennas often use sets of fat full wave dipols,

with

a matching circuit consisting of wuarter wave sections, all made on a
single PCB. These seem to work, at least some of them, but only over a
pretty limited bandwidth.

A biconical antenna is a balanced antenna. When feeding it with a coax
cable, a suitable balun should be used, even when the antenna is placed
vertically. Without a balun, running the coax (and a metal mast!)

inside

the lower element should be better than placing them outside, but there
will always be interaction.

A discone is also closer to a balanced than an unbalanced antenna!

Dissolving the solid cones and discs into sets of spokes, the behavior
changes very much! Some authors claim that using 8 spokes is the same

as

a

solid cone, but this is not true. Just try it!

In any case, the claim that a discone or biconical antenna is almost a
DC-to-daylight antenna is simply not true, even in RX, let alone in TX!
Which of course doesn't hinder manufacturers to keep claiming this, and
book authors to keep copying and pasting that claim without having ever
built such an antenna themselves.

Manfred

--

*Dave - W?LEV*


--
Dave - W?LEV

I checked this antenna on the Moonraker site, specifically amateur radio
antennas. It's rated for ONLY the 70-CM BAND.
[image: image.png]
Sure, it will receive over a wide band with relatively poor efficiency, but
for transmit - low SWR - it's rated for only 130 to 175 MHz and 410 to 475
MHz. This is pretty much what the SWR sweeps have shown with the exception
of the 2-meter and aircraft bands. The SWR sweeps that have been shown in
this thread exhibit low SWR ONLY in the 70-CM BAND. That's what the spec's
show!

Further, the claimed 5.5 dBi over a standard discone is bogus. A standard
discone radiates (and receives) pretty much like a 1/4-wavelength over an
image plane. 5.5 dBi over this is not realizable. And I can imagine, if
it were, that figure would apply only to 70-cm.

Dave - W?LEV




On Thu, Aug 3, 2023 at 4:19?AM Bob Ecclestone VK2ZRE <becclest@...>
wrote:

I am surprised some folk on this group have rubbished Moonraker Antennas.
I know Moonraker HF antennas are used on some Australian Navy ships, so
I don't think they are really "Dollar Shop junk."
I don't have any connection with either Moonraker or the the Australian
Navy.
So perhaps those with complaints may need to examine their installation
practices.
Or contact Moonraker or their dealer for support.
Just my 2c worth.

Cheers...Bob VK2ZRE


On 3/08/2023 2:33 am, Clyde Spencer wrote:

one has to consider the environment, not discussed prior in this thread.

If

there were any metal or other electrically conductive material near the
antenna when tested that could be a possible cause for the difference in
measurement data and that which is published.
*Clyde K. Spencer*



On Wed, Aug 2, 2023 at 11:09?AM Jim via groups.io <teotwaki=
[email protected]> wrote:

This antenna is related to what antenna design literature calls a
“产颈肠辞苍颈肠补濒“

- - Biconical antennas have dipole characteristics. The double cone
elements structure contributes to their wider bandwidth. The antenna
becomes more broadband as the cone angle increases. - -

Search on that name for design and results discussions

Jim