Marine Radio RF Ground Question
 

What elements make a good Radio Frequency
(RF) ground system in a yacht?

Bart Senior

Marine Radio RF Ground Question
 

A counterpoise.



"N1EE" wrote in message
om...
What elements make a good Radio Frequency
(RF) ground system in a yacht?

Bart Senior

Marine Radio RF Ground Question
 

Mostly, hydrogen, oxygen, sodium, chorine and copper. In the right
proportions and places of course.

Cheers

N1EE wrote:

What elements make a good Radio Frequency
(RF) ground system in a yacht?

Bart Senior

Marine Radio RF Ground Question
 

What is the best way to make a counterpoise for
a boat?

"Gay Sailor" wrote

A counterpoise.


"N1EE" wrote

What elements make a good Radio Frequency
(RF) ground system in a yacht?

Marine Radio RF Ground Question
 

The simplest is a variable series LC circuit that tunes the ground path for
the lowest impedance possible.
A caveat though, the voltage across either element is the circuit Q times
the applied voltage. If you drive a 12volt Vcc amplifier (voltage swing of
24 volts) into a circuit with a Q of 10, there is 240 volts across the
series inductor and 240 volts across the series capacitor. So for your 12
volt output driver one would be wise to use 500 volt capacitors and
inductors.

Why not just convert your backstay antenna into a sleeve dipole? No ground
is necessary for this antenna, the radiation pattern is good and the
bandwidth is ok. I ran some NEC simulations on a 35 foot sleeve dipole over
a seawater ground and found the patterns and SWR to be quite good. If I get
a round to it I'll post the plans for such an antenna on a website. Any
engineer worth the title can look up a sleeve dipole on the net and figure
out how to build one too.

Swishy tither boy gay sailor!


"N1EE" wrote in message
m...
What is the best way to make a counterpoise for
a boat?

"Gay Sailor" wrote

A counterpoise.


"N1EE" wrote

What elements make a good Radio Frequency
(RF) ground system in a yacht?

Marine Radio RF Ground Question
 

http://www.arising.com.au/people/Hol...ph/counter.htm



"N1EE" wrote in message
om...
What elements make a good Radio Frequency
(RF) ground system in a yacht?

Bart Senior

Marine Radio RF Ground Question
 

Gilligan, you're way too nerdy for most of these people...

"Gay Sailor" wrote in message
link.net...
The simplest is a variable series LC circuit that tunes the ground path
for
the lowest impedance possible.
A caveat though, the voltage across either element is the circuit Q times
the applied voltage. If you drive a 12volt Vcc amplifier (voltage swing
of
24 volts) into a circuit with a Q of 10, there is 240 volts across the
series inductor and 240 volts across the series capacitor. So for your 12
volt output driver one would be wise to use 500 volt capacitors and
inductors.

Why not just convert your backstay antenna into a sleeve dipole? No ground
is necessary for this antenna, the radiation pattern is good and the
bandwidth is ok. I ran some NEC simulations on a 35 foot sleeve dipole
over
a seawater ground and found the patterns and SWR to be quite good. If I
get
a round to it I'll post the plans for such an antenna on a website. Any
engineer worth the title can look up a sleeve dipole on the net and figure
out how to build one too.

Swishy tither boy gay sailor!


"N1EE" wrote in message
m...
What is the best way to make a counterpoise for
a boat?

"Gay Sailor" wrote

A counterpoise.


"N1EE" wrote

What elements make a good Radio Frequency
(RF) ground system in a yacht?

Marine Radio RF Ground Question
 

That would be interesting, please do it.

Cheers
Gay Sailor wrote:

The simplest is a variable series LC circuit that tunes the ground path for
the lowest impedance possible.
A caveat though, the voltage across either element is the circuit Q times
the applied voltage. If you drive a 12volt Vcc amplifier (voltage swing of
24 volts) into a circuit with a Q of 10, there is 240 volts across the
series inductor and 240 volts across the series capacitor. So for your 12
volt output driver one would be wise to use 500 volt capacitors and
inductors.

Why not just convert your backstay antenna into a sleeve dipole? No ground
is necessary for this antenna, the radiation pattern is good and the
bandwidth is ok. I ran some NEC simulations on a 35 foot sleeve dipole over
a seawater ground and found the patterns and SWR to be quite good. If I get
a round to it I'll post the plans for such an antenna on a website. Any
engineer worth the title can look up a sleeve dipole on the net and figure
out how to build one too.

Swishy tither boy gay sailor!


"N1EE" wrote in message
m...

What is the best way to make a counterpoise for
a boat?

"Gay Sailor" wrote


A counterpoise.

"N1EE" wrote

What elements make a good Radio Frequency
(RF) ground system in a yacht?

Marine Radio RF Ground Question
 

Gay Sailor wrote:

A caveat though, the voltage across either element is the circuit Q times
the applied voltage. If you drive a 12volt Vcc amplifier (voltage swing of
24 volts) into a circuit with a Q of 10, there is 240 volts across the
series inductor and 240 volts across the series capacitor. So for your 12
volt output driver one would be wise to use 500 volt capacitors and
inductors.


Can you explain this. I though that for a parallel LC the impedence went
to infinite at resonance (f=1/2pi sqrt(LC)) so that Vin=Vout.

What am I missing?

Cheers

Marine Radio RF Ground Question
 

Nav wrote:

Can you explain this. I though that for a parallel LC the impedence
went to infinite at resonance (f=1/2pi sqrt(LC)) so that Vin=Vout.

What am I missing?

Getting beyond my knowledge (or memory), but Gilly did say that the LC
circut is series - would that work better?


--
Wally
www.artbywally.com
www.wally.myby.co.uk/music

Marine Radio RF Ground Question
 

If it's series LC doesn't the impedence drop to zero?

Cheers

Wally wrote:

Nav wrote:


Can you explain this. I though that for a parallel LC the impedence
went to infinite at resonance (f=1/2pi sqrt(LC)) so that Vin=Vout.

What am I missing?


Getting beyond my knowledge (or memory), but Gilly did say that the LC
circut is series - would that work better?


--
Wally
www.artbywally.com
www.wally.myby.co.uk/music

Marine Radio RF Ground Question
 

Nav wrote:

If it's series LC doesn't the impedence drop to zero?

Just had a play with a spreadsheet - there's a dip in Z in series, and a
rise with parallel.


--
Wally
www.artbywally.com
www.wally.myby.co.uk/music

Marine Radio RF Ground Question
 

That's what I thought. How can a low impedence increase voltage? Can you
explain Gilly's idea to me?

Cheers

Wally wrote:

Nav wrote:


If it's series LC doesn't the impedence drop to zero?


Just had a play with a spreadsheet - there's a dip in Z in series, and a
rise with parallel.


--
Wally
www.artbywally.com
www.wally.myby.co.uk/music

Marine Radio RF Ground Question
 

Nav wrote:

That's what I thought. How can a low impedence increase voltage? Can
you explain Gilly's idea to me?

'Fraid not, but I'll have a guess... :-)

With a parallel cct, Z either side of resonance is low, which would develop
a lower voltage across the two components. The series cct presents high Z
either side of resonance. IOW, the high voltage developed across each
component in the series cct is outside the tuned frequency - at low F on one
component, high F on the other.

Alternatively, and I really am guessing here - how about something to do
with phase effects at resonance? All that leading and lagging of current WRT
voltage.


--
Wally
www.artbywally.com
www.wally.myby.co.uk/music

Marine Radio RF Ground Question
 

Wally wrote:

Nav wrote:


That's what I thought. How can a low impedence increase voltage? Can
you explain Gilly's idea to me?


'Fraid not, but I'll have a guess... :-)

With a parallel cct, Z either side of resonance is low, which would develop
a lower voltage across the two components. The series cct presents high Z
either side of resonance. IOW, the high voltage developed across each
component in the series cct is outside the tuned frequency - at low F on one
component, high F on the other.

Alternatively, and I really am guessing here - how about something to do
with phase effects at resonance? All that leading and lagging of current WRT
voltage.


As far as I understand it, the voltage is just the current times the
impedence. Similarly, the current is only produced by the driver (Vin)
so how can Vout be bigger than Vin (there's no mention of a transformer)?

Cheers

Marine Radio RF Ground Question
 

The voltage across the inductor is 180 degrees out of phase with the voltage
across the capacitor.

A parallel LC resonator has a circulating current of the circuit Q times the
applied current. The components better be rated for high current.

These concepts are very basic radio theory, the type of questions asked on
the amateur radio exam.

In practice a pi or t type network may be better for tuning the ground
because it would have wider bandwidth than a series LC circuit.

It is beneficial to have the ground at a low impedance, that's why series LC
is used.


"Nav" wrote in message
...


Wally wrote:

Nav wrote:


That's what I thought. How can a low impedence increase voltage? Can
you explain Gilly's idea to me?


'Fraid not, but I'll have a guess... :-)

With a parallel cct, Z either side of resonance is low, which would
develop
a lower voltage across the two components. The series cct presents high
Z
either side of resonance. IOW, the high voltage developed across each
component in the series cct is outside the tuned frequency - at low F on
one
component, high F on the other.

Alternatively, and I really am guessing here - how about something to do
with phase effects at resonance? All that leading and lagging of current
WRT
voltage.


As far as I understand it, the voltage is just the current times the
impedence. Similarly, the current is only produced by the driver (Vin)
so how can Vout be bigger than Vin (there's no mention of a transformer)?

Cheers

Marine Radio RF Ground Question
 

Gay Sailor wrote:

The voltage across the inductor is 180 degrees out of phase with the voltage
across the capacitor.

A parallel LC resonator has a circulating current of the circuit Q times the
applied current. The components better be rated for high current.

So what's the voltage across the resonator?

Cheers

Marine Radio RF Ground Question
 

Depends on the circuit driving it.



"Nav" wrote in message
...


Gay Sailor wrote:

The voltage across the inductor is 180 degrees out of phase with the
voltage
across the capacitor.

A parallel LC resonator has a circulating current of the circuit Q times
the
applied current. The components better be rated for high current.

So what's the voltage across the resonator?

Cheers