I got a cheap door access controller from Hong Kong. The keyfob has to be placed within 1.5 inches of the keypad for it to be picked up. Is it possible to make it sensitive enough so that approaching the doorway with the keyfob in your pocket would unlock the door? (Much like some cars do). It picks up the fob using a coil of wire round the edge of the keypad (which is 10cm across). The coil looks like about 100 winds of thin wire of the same sort used in CRTs. If I made a huge version of this coil right round the doorway, would the range be increased? Or would there not be enough power in the chip to transmit over that much area?

--
A young blonde girl goes to the doctor for a physical. The doctor puts his stethoscope up to the girl's chest and says, "Big breaths."
The girl replies, "Yeth and I'm not even thixteen."

Gefreiter Krueger wrote:
I got a cheap door access controller from Hong Kong. The keyfob has to
be placed within 1.5 inches of the keypad for it to be picked up. Is it
possible to make it sensitive enough so that approaching the doorway
with the keyfob in your pocket would unlock the door? (Much like some
cars do). It picks up the fob using a coil of wire round the edge of
the keypad (which is 10cm across). The coil looks like about 100 winds
of thin wire of the same sort used in CRTs. If I made a huge version of
this coil right round the doorway, would the range be increased? Or
would there not be enough power in the chip to transmit over that much
area?

Not a lot you can do without a lot of test equipment and knowledge.
These things are specified for a range of 100mm maximum. There is a
different standard to cover the 100cm units that are possibly used in cars.
1) you need extra power so that sufficient RF power arrives at the tag
to power it up.
2)Tinkering with the coil will de-tune it and will transmit far less
power and reduce the RF sensitivity.

On Thu, 23 May 2013 20:00:30 +0100, Bob Minchin wrote:

Gefreiter Krueger wrote:
I got a cheap door access controller from Hong Kong. The keyfob has to
be placed within 1.5 inches of the keypad for it to be picked up. Is it
possible to make it sensitive enough so that approaching the doorway
with the keyfob in your pocket would unlock the door? (Much like some
cars do). It picks up the fob using a coil of wire round the edge of
the keypad (which is 10cm across). The coil looks like about 100 winds
of thin wire of the same sort used in CRTs. If I made a huge version of
this coil right round the doorway, would the range be increased? Or
would there not be enough power in the chip to transmit over that much
area?

Not a lot you can do without a lot of test equipment and knowledge.
These things are specified for a range of 100mm maximum. There is a
different standard to cover the 100cm units that are possibly used in cars.
1) you need extra power so that sufficient RF power arrives at the tag
to power it up.
2)Tinkering with the coil will de-tune it and will transmit far less
power and reduce the RF sensitivity.

Is amplifying the signal an easy thing to achieve? If not, where can I buy one with the same range as a car one?

Bloody advert said 10 metres. I bought it ages ago, the ones on sale now say 10cm (I assume it was a typo). It's not 10cm though, it's more like 3.

--
A pack-a-day smoker will lose approximately 2 teeth every 10 years.

Gefreiter Krueger wrote:
On Thu, 23 May 2013 20:00:30 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:
I got a cheap door access controller from Hong Kong. The keyfob has to
be placed within 1.5 inches of the keypad for it to be picked up. Is it
possible to make it sensitive enough so that approaching the doorway
with the keyfob in your pocket would unlock the door? (Much like some
cars do). It picks up the fob using a coil of wire round the edge of
the keypad (which is 10cm across). The coil looks like about 100 winds
of thin wire of the same sort used in CRTs. If I made a huge version of
this coil right round the doorway, would the range be increased? Or
would there not be enough power in the chip to transmit over that much
area?

Not a lot you can do without a lot of test equipment and knowledge.
These things are specified for a range of 100mm maximum. There is a
different standard to cover the 100cm units that are possibly used in
cars.
1) you need extra power so that sufficient RF power arrives at the tag
to power it up.
2)Tinkering with the coil will de-tune it and will transmit far less
power and reduce the RF sensitivity.

Is amplifying the signal an easy thing to achieve? If not, where can I
buy one with the same range as a car one?

Bloody advert said 10 metres. I bought it ages ago, the ones on sale
now say 10cm (I assume it was a typo). It's not 10cm though, it's more
like 3.

I'm afraid not,
The problem is that the amplifier much switch very rapidly and the
receiver must recover very quickly from the overload.
This is akin to having your head inside a drum that is being hit hard
and then needing to hear a pin drop a few microseconds later!

What you have is a proximity system which must have no MORE than 100mm
range for security reasons such as payment system (contactless smart
cards, oyster cards etc) These are described by ISO 14443

The up to 100cm system are 'vicinity' systems and covered by ISO 15693
and should be what you desire.
Note that others will be able to read your tag at up to 100cm range and
may then clone the information to gain access to your door.
A balance of security and convenience needs to be considered.

On Thu, 23 May 2013 21:21:29 +0100, Bob Minchin wrote:

Gefreiter Krueger wrote:
On Thu, 23 May 2013 20:00:30 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:
I got a cheap door access controller from Hong Kong. The keyfob has to
be placed within 1.5 inches of the keypad for it to be picked up. Is it
possible to make it sensitive enough so that approaching the doorway
with the keyfob in your pocket would unlock the door? (Much like some
cars do). It picks up the fob using a coil of wire round the edge of
the keypad (which is 10cm across). The coil looks like about 100 winds
of thin wire of the same sort used in CRTs. If I made a huge version of
this coil right round the doorway, would the range be increased? Or
would there not be enough power in the chip to transmit over that much
area?

Not a lot you can do without a lot of test equipment and knowledge.
These things are specified for a range of 100mm maximum. There is a
different standard to cover the 100cm units that are possibly used in
cars.
1) you need extra power so that sufficient RF power arrives at the tag
to power it up.
2)Tinkering with the coil will de-tune it and will transmit far less
power and reduce the RF sensitivity.

Is amplifying the signal an easy thing to achieve? If not, where can I
buy one with the same range as a car one?

Bloody advert said 10 metres. I bought it ages ago, the ones on sale
now say 10cm (I assume it was a typo). It's not 10cm though, it's more
like 3.

I'm afraid not,
The problem is that the amplifier much switch very rapidly and the
receiver must recover very quickly from the overload.
This is akin to having your head inside a drum that is being hit hard
and then needing to hear a pin drop a few microseconds later!

What you have is a proximity system which must have no MORE than 100mm
range for security reasons such as payment system (contactless smart
cards, oyster cards etc) These are described by ISO 14443

The up to 100cm system are 'vicinity' systems and covered by ISO 15693
and should be what you desire.
Note that others will be able to read your tag at up to 100cm range and
may then clone the information to gain access to your door.
A balance of security and convenience needs to be considered.

Presumably it's not that easy to read and copy it, otherwise all these keyless cars would be getting stolen. Perhaps some kind of encrypted code is sent both ways?

I shall play around with slightly different aerials and see what I can do. Even doubling the distance would be good, at present you have to almost touch the fob on the panel, and have it orientated correctly aswell.

Is the signal stronger INSIDE the loop of the aerial perhaps? If I brought the loop out of the casing and placed it round the frame of one of the door's window panels, the fob could easily be inserted into the coil by touching the pane of glass with it.

--
G.A.Y. - Got Aids Yet?

Gefreiter Krueger wrote:
On Thu, 23 May 2013 21:21:29 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:
On Thu, 23 May 2013 20:00:30 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:
I got a cheap door access controller from Hong Kong. The keyfob
has to
be placed within 1.5 inches of the keypad for it to be picked up.
Is it
possible to make it sensitive enough so that approaching the doorway
with the keyfob in your pocket would unlock the door? (Much like some
cars do). It picks up the fob using a coil of wire round the edge of
the keypad (which is 10cm across). The coil looks like about 100
winds
of thin wire of the same sort used in CRTs. If I made a huge
version of
this coil right round the doorway, would the range be increased? Or
would there not be enough power in the chip to transmit over that much
area?

Not a lot you can do without a lot of test equipment and knowledge.
These things are specified for a range of 100mm maximum. There is a
different standard to cover the 100cm units that are possibly used in
cars.
1) you need extra power so that sufficient RF power arrives at the tag
to power it up.
2)Tinkering with the coil will de-tune it and will transmit far less
power and reduce the RF sensitivity.

Is amplifying the signal an easy thing to achieve? If not, where can I
buy one with the same range as a car one?

Bloody advert said 10 metres. I bought it ages ago, the ones on sale
now say 10cm (I assume it was a typo). It's not 10cm though, it's more
like 3.

I'm afraid not,
The problem is that the amplifier much switch very rapidly and the
receiver must recover very quickly from the overload.
This is akin to having your head inside a drum that is being hit hard
and then needing to hear a pin drop a few microseconds later!

What you have is a proximity system which must have no MORE than 100mm
range for security reasons such as payment system (contactless smart
cards, oyster cards etc) These are described by ISO 14443

The up to 100cm system are 'vicinity' systems and covered by ISO 15693
and should be what you desire.
Note that others will be able to read your tag at up to 100cm range and
may then clone the information to gain access to your door.
A balance of security and convenience needs to be considered.

Presumably it's not that easy to read and copy it, otherwise all these
keyless cars would be getting stolen. Perhaps some kind of encrypted
code is sent both ways?

I shall play around with slightly different aerials and see what I can
do. Even doubling the distance would be good, at present you have to
almost touch the fob on the panel, and have it orientated correctly aswell.

Is the signal stronger INSIDE the loop of the aerial perhaps? If I
brought the loop out of the casing and placed it round the frame of one
of the door's window panels, the fob could easily be inserted into the
coil by touching the pane of glass with it.

You might get a little more inside the coil just, but it is vital not to
de-tune the antenna from about 13MHz
The codes are rolling codes with challenge and response but there are
ways of stopping it rolling and the oyster card codes have been cracked
but fraud does not yield enough monetary advantage for the crims who
ride in cars not trains
Contactless payment cards are under attack by the bad guys. More
profitable but still low value transactions.
Read up on the work being undertaken by Markus Kuhn and his department
at Cambridge University.
Higher security car keys have just lead to increasing occurrences of
car-jacking where the crims nick the car keys and the car from the
driver or break into the house to get the keys to the cars in the drive.
These system are secure enough until broken to the extent that the banks
and insurance companies will no longer pay up.

On Thu, 23 May 2013 21:53:37 +0100, Bob Minchin wrote:

Gefreiter Krueger wrote:
On Thu, 23 May 2013 21:21:29 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:
On Thu, 23 May 2013 20:00:30 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:

Not a lot you can do without a lot of test equipment and knowledge.
These things are specified for a range of 100mm maximum. There is a
different standard to cover the 100cm units that are possibly used in
cars.
1) you need extra power so that sufficient RF power arrives at the tag
to power it up.
2)Tinkering with the coil will de-tune it and will transmit far less
power and reduce the RF sensitivity.

Is amplifying the signal an easy thing to achieve? If not, where can I
buy one with the same range as a car one?

Bloody advert said 10 metres. I bought it ages ago, the ones on sale
now say 10cm (I assume it was a typo). It's not 10cm though, it's more
like 3.

I'm afraid not,
The problem is that the amplifier much switch very rapidly and the
receiver must recover very quickly from the overload.
This is akin to having your head inside a drum that is being hit hard
and then needing to hear a pin drop a few microseconds later!

What you have is a proximity system which must have no MORE than 100mm
range for security reasons such as payment system (contactless smart
cards, oyster cards etc) These are described by ISO 14443

The up to 100cm system are 'vicinity' systems and covered by ISO 15693
and should be what you desire.
Note that others will be able to read your tag at up to 100cm range and
may then clone the information to gain access to your door.
A balance of security and convenience needs to be considered.

Presumably it's not that easy to read and copy it, otherwise all these
keyless cars would be getting stolen. Perhaps some kind of encrypted
code is sent both ways?

I shall play around with slightly different aerials and see what I can
do. Even doubling the distance would be good, at present you have to
almost touch the fob on the panel, and have it orientated correctly aswell.

Is the signal stronger INSIDE the loop of the aerial perhaps? If I
brought the loop out of the casing and placed it round the frame of one
of the door's window panels, the fob could easily be inserted into the
coil by touching the pane of glass with it.

You might get a little more inside the coil just, but it is vital not to
de-tune the antenna from about 13MHz
The codes are rolling codes with challenge and response but there are
ways of stopping it rolling and the oyster card codes have been cracked
but fraud does not yield enough monetary advantage for the crims who
ride in cars not trains
Contactless payment cards are under attack by the bad guys. More
profitable but still low value transactions.
Read up on the work being undertaken by Markus Kuhn and his department
at Cambridge University.
Higher security car keys have just lead to increasing occurrences of
car-jacking where the crims nick the car keys and the car from the
driver or break into the house to get the keys to the cars in the drive.
These system are secure enough until broken to the extent that the banks
and insurance companies will no longer pay up.

Not knowing much about antennas...... at present it appears to have a 10cm diameter square coil with about 100 turns. Can I make that larger without detuning it? What effect do the diameter and number of turns have?

--
Why does a one-story brothel make more money than a two-story brothel?
Because there's no ****ing overhead.

On May 23, 9:38*pm, "Gefreiter Krueger" wrote:
On Thu, 23 May 2013 21:21:29 +0100, Bob Minchin wrote:
Gefreiter Krueger wrote:
On Thu, 23 May 2013 20:00:30 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:
I got a cheap door access controller from Hong Kong. *The keyfob has to
be placed within 1.5 inches of the keypad for it to be picked up. *Is it
possible to make it sensitive enough so that approaching the doorway
with the keyfob in your pocket would unlock the door? *(Much like some
cars do). *It picks up the fob using a coil of wire round the edge of
the keypad (which is 10cm across). *The coil looks like about 100 winds
of thin wire of the same sort used in CRTs. *If I made a huge version of
this coil right round the doorway, would the range be increased? *Or
would there not be enough power in the chip to transmit over that much
area?

Not *a lot you can do without a lot of test equipment and knowledge..
These things are specified for a range *of 100mm maximum. There is a
different standard to cover the 100cm units that are possibly used in
cars.
1) you need extra power so that sufficient RF power arrives at the tag
to power it up.
2)Tinkering with the coil will de-tune it and will transmit far less
power and reduce the RF sensitivity.

Is amplifying the signal an easy thing to achieve? *If not, where can I
buy one with the same range as a car one?

Bloody advert said 10 metres. *I bought it ages ago, the ones on sale
now say 10cm (I assume it was a typo). *It's not 10cm though, it's more
like 3.

I'm afraid not,
The problem is that the amplifier much switch very rapidly and the
receiver must recover very quickly from the overload.
This is akin to having your head inside a drum that is being hit hard
and then needing to hear a pin drop a few microseconds later!

What you have is a proximity system which must have no MORE than 100mm
range for security reasons such as payment system (contactless smart
cards, oyster cards etc) These are described by ISO 14443

The up to 100cm system are 'vicinity' systems and covered by ISO 15693
and should be what you desire.
Note that others will be able to read your tag at up to 100cm range and
may then clone the information to gain access to your door.
A balance of security and convenience needs to be considered.

Presumably it's not that easy to read and copy it, otherwise all these keyless cars would be getting stolen. *Perhaps some kind of encrypted code is sent both ways?

I shall play around with slightly different aerials and see what I can do.. *Even doubling the distance would be good, at present you have to almost touch the fob on the panel, and have it orientated correctly aswell.

Is the signal stronger INSIDE the loop of the aerial perhaps? *If I brought the loop out of the casing and placed it round the frame of one of the door's window panels, the fob could easily be inserted into the coil by touching the pane of glass with it.

--
G.A.Y. - Got Aids Yet?

A.I.D.S. = Arsehole Injected Death Sentence

I think you are missing the point. the aerial is part of the receiver on the
home side and their is no power in the fob and the thing has to charge up
a capacitor to run the receiver and transmitter in the fob for it to have a
chance to work.
I think it sounds like you need a device as used in cars, but remember the
security is probably part of the computer on board the car and the fob is
merely made to match it in some way by interrogation back and forth.

I still prefer good old radio systems myself, as most of the time you only
need batteries.

Brian

--
From the Sofa of Brian Gaff Reply address is active
"harry" wrote in message
...
On May 23, 9:38 pm, "Gefreiter Krueger" wrote:
On Thu, 23 May 2013 21:21:29 +0100, Bob Minchin
wrote:
Gefreiter Krueger wrote:
On Thu, 23 May 2013 20:00:30 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:
I got a cheap door access controller from Hong Kong. The keyfob has
to
be placed within 1.5 inches of the keypad for it to be picked up. Is
it
possible to make it sensitive enough so that approaching the doorway
with the keyfob in your pocket would unlock the door? (Much like some
cars do). It picks up the fob using a coil of wire round the edge of
the keypad (which is 10cm across). The coil looks like about 100
winds
of thin wire of the same sort used in CRTs. If I made a huge version
of
this coil right round the doorway, would the range be increased? Or
would there not be enough power in the chip to transmit over that
much
area?

Not a lot you can do without a lot of test equipment and knowledge.
These things are specified for a range of 100mm maximum. There is a
different standard to cover the 100cm units that are possibly used in
cars.
1) you need extra power so that sufficient RF power arrives at the tag
to power it up.
2)Tinkering with the coil will de-tune it and will transmit far less
power and reduce the RF sensitivity.

Is amplifying the signal an easy thing to achieve? If not, where can I
buy one with the same range as a car one?

Bloody advert said 10 metres. I bought it ages ago, the ones on sale
now say 10cm (I assume it was a typo). It's not 10cm though, it's more
like 3.

I'm afraid not,
The problem is that the amplifier much switch very rapidly and the
receiver must recover very quickly from the overload.
This is akin to having your head inside a drum that is being hit hard
and then needing to hear a pin drop a few microseconds later!

What you have is a proximity system which must have no MORE than 100mm
range for security reasons such as payment system (contactless smart
cards, oyster cards etc) These are described by ISO 14443

The up to 100cm system are 'vicinity' systems and covered by ISO 15693
and should be what you desire.
Note that others will be able to read your tag at up to 100cm range and
may then clone the information to gain access to your door.
A balance of security and convenience needs to be considered.

Presumably it's not that easy to read and copy it, otherwise all these
keyless cars would be getting stolen. Perhaps some kind of encrypted code
is sent both ways?

I shall play around with slightly different aerials and see what I can do.
Even doubling the distance would be good, at present you have to almost
touch the fob on the panel, and have it orientated correctly aswell.

Is the signal stronger INSIDE the loop of the aerial perhaps? If I brought
the loop out of the casing and placed it round the frame of one of the
door's window panels, the fob could easily be inserted into the coil by
touching the pane of glass with it.

--
G.A.Y. - Got Aids Yet?

A.I.D.S. = Arsehole Injected Death Sentence

Gefreiter Krueger wrote:
On Thu, 23 May 2013 21:53:37 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:
On Thu, 23 May 2013 21:21:29 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:
On Thu, 23 May 2013 20:00:30 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:

Not a lot you can do without a lot of test equipment and knowledge.
These things are specified for a range of 100mm maximum. There is a
different standard to cover the 100cm units that are possibly used in
cars.
1) you need extra power so that sufficient RF power arrives at the
tag
to power it up.
2)Tinkering with the coil will de-tune it and will transmit far less
power and reduce the RF sensitivity.

Is amplifying the signal an easy thing to achieve? If not, where
can I
buy one with the same range as a car one?

Bloody advert said 10 metres. I bought it ages ago, the ones on sale
now say 10cm (I assume it was a typo). It's not 10cm though, it's
more
like 3.

I'm afraid not,
The problem is that the amplifier much switch very rapidly and the
receiver must recover very quickly from the overload.
This is akin to having your head inside a drum that is being hit hard
and then needing to hear a pin drop a few microseconds later!

What you have is a proximity system which must have no MORE than 100mm
range for security reasons such as payment system (contactless smart
cards, oyster cards etc) These are described by ISO 14443

The up to 100cm system are 'vicinity' systems and covered by ISO 15693
and should be what you desire.
Note that others will be able to read your tag at up to 100cm range and
may then clone the information to gain access to your door.
A balance of security and convenience needs to be considered.

Presumably it's not that easy to read and copy it, otherwise all these
keyless cars would be getting stolen. Perhaps some kind of encrypted
code is sent both ways?

I shall play around with slightly different aerials and see what I can
do. Even doubling the distance would be good, at present you have to
almost touch the fob on the panel, and have it orientated correctly
aswell.

Is the signal stronger INSIDE the loop of the aerial perhaps? If I
brought the loop out of the casing and placed it round the frame of one
of the door's window panels, the fob could easily be inserted into the
coil by touching the pane of glass with it.

You might get a little more inside the coil just, but it is vital not to
de-tune the antenna from about 13MHz
The codes are rolling codes with challenge and response but there are
ways of stopping it rolling and the oyster card codes have been cracked
but fraud does not yield enough monetary advantage for the crims who
ride in cars not trains
Contactless payment cards are under attack by the bad guys. More
profitable but still low value transactions.
Read up on the work being undertaken by Markus Kuhn and his department
at Cambridge University.
Higher security car keys have just lead to increasing occurrences of
car-jacking where the crims nick the car keys and the car from the
driver or break into the house to get the keys to the cars in the drive.
These system are secure enough until broken to the extent that the banks
and insurance companies will no longer pay up.

Not knowing much about antennas...... at present it appears to have a
10cm diameter square coil with about 100 turns. Can I make that larger
without detuning it? What effect do the diameter and number of turns have?

You need to measure the inductance of the coil - and keep that similar
in any new coil however the stray capacitance will change and so you
need a network analyser. Not a simple job at all. Antennas are a black art.
Forget it and buy a proper device specified for what you want to do.
Warehouse tracking systems operating at 125kHz might be the way to go.
They will read a pallet load of goods as they are driven through a
doorway on a fork lift.

On Fri, 24 May 2013 06:34:43 +0100, harry wrote:

On May 23, 9:38 pm, "Gefreiter Krueger" wrote:
On Thu, 23 May 2013 21:21:29 +0100, Bob Minchin wrote:
Gefreiter Krueger wrote:
On Thu, 23 May 2013 20:00:30 +0100, Bob Minchin
wrote:

Gefreiter Krueger wrote:
I got a cheap door access controller from Hong Kong. The keyfob has to
be placed within 1.5 inches of the keypad for it to be picked up. Is it
possible to make it sensitive enough so that approaching the doorway
with the keyfob in your pocket would unlock the door? (Much like some
cars do). It picks up the fob using a coil of wire round the edge of
the keypad (which is 10cm across). The coil looks like about 100 winds
of thin wire of the same sort used in CRTs. If I made a huge version of
this coil right round the doorway, would the range be increased? Or
would there not be enough power in the chip to transmit over that much
area?

Not a lot you can do without a lot of test equipment and knowledge.
These things are specified for a range of 100mm maximum. There is a
different standard to cover the 100cm units that are possibly used in
cars.
1) you need extra power so that sufficient RF power arrives at the tag
to power it up.
2)Tinkering with the coil will de-tune it and will transmit far less
power and reduce the RF sensitivity.

Is amplifying the signal an easy thing to achieve? If not, where can I
buy one with the same range as a car one?

Bloody advert said 10 metres. I bought it ages ago, the ones on sale
now say 10cm (I assume it was a typo). It's not 10cm though, it's more
like 3.

I'm afraid not,
The problem is that the amplifier much switch very rapidly and the
receiver must recover very quickly from the overload.
This is akin to having your head inside a drum that is being hit hard
and then needing to hear a pin drop a few microseconds later!

What you have is a proximity system which must have no MORE than 100mm
range for security reasons such as payment system (contactless smart
cards, oyster cards etc) These are described by ISO 14443

The up to 100cm system are 'vicinity' systems and covered by ISO 15693
and should be what you desire.
Note that others will be able to read your tag at up to 100cm range and
may then clone the information to gain access to your door.
A balance of security and convenience needs to be considered.

Presumably it's not that easy to read and copy it, otherwise all these keyless cars would be getting stolen. Perhaps some kind of encrypted code is sent both ways?

I shall play around with slightly different aerials and see what I can do. Even doubling the distance would be good, at present you have to almost touch the fob on the panel, and have it orientated correctly aswell.

Is the signal stronger INSIDE the loop of the aerial perhaps? If I brought the loop out of the casing and placed it round the frame of one of the door's window panels, the fob could easily be inserted into the coil by touching the pane of glass with it.

--
G.A.Y. - Got Aids Yet?

A.I.D.S. = Arsehole Injected Death Sentence

:-)

--
Debugger: a tool to remove evidence of rear entry.