[CQ-Contest] When RF is not your friend

AC0W ac0w at charter.net
Sun Apr 6 12:53:59 EDT 2014

With RFID there are many things that affect the effective range very similar
to our contest station.

On the chip side you have both active and passive systems. 

As noted the toll pass system use active systems with a battery to improve
distance and speed.

On the passive systems to improve distance they imbed better antennas in the
card or device. On security systems where an RFID card is used (same size as
credit card) if you carefully peel away the protective outer plastic you
will find basically a metal foil antenna coiled around the perimeter of the
card to improve range.

On a credit card where the chip is exposed these have very small antennas to
reduce the effective range.

On the other side to increase the range takes power, larger antennas and
more sensitive receiver, QRO versus QRP.

The toll booths and ski resorts if you look carefully you will see big
powerful antennas to achieve greater distance, where as the credit card
readers are small, very portable, low power, as result effective only over
small distance.

There are security codes built into the devices to help prevent different
systems from reading other systems RFID chips. I know smart people can break
these but it is just one more step to help make it more difficult to do.

While I can't say it is impossible to do, it is very hard for someone to be
inconspicuous while reading your credit card information or passport
information with today's technology without spending a great deal of money
up front.


Message: 4
Date: Sat, 05 Apr 2014 18:38:57 -0600
From: Barry <w2up at comcast.net>
To: cq-contest at contesting.com
Subject: Re: [CQ-Contest] When RF is not your friend
Message-ID: <5340A221.2070603 at comcast.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

To add one more to the list...
Vail Resorts ski passes have RF ID chips to track you as you enter a 
lift.  The transponders are about 6 feet over head.
Barry W2UP

On 4/5/2014 15:51, Michael Clarson wrote:
> Bill: E-ZPass transponders have a battery in them which typically last 3
> 5 years. --Mike, WV2ZOW
> On Fri, Apr 4, 2014 at 9:47 PM, <KB3LIX at comcast.net> wrote:
>> There are a few manufacturers out there that manufacture
>> wallets and womens purses lined with metallic foil,
>> so all the contents are protected from interrogation.
>> You do NOT have to get that close to interrogate RFID chips.
>> Think "EZ-PASS" or other highway/turnpike payment systems.
>> bill
>> ----- Original Message -----
>> From: "Charles Harpole" <k4vud at hotmail.com>
>> To: "Contest Internet" <cq-contest at contesting.com>
>> Sent: Friday, April 4, 2014 4:22:31 PM
>> Subject: [CQ-Contest] When RF is not your friend
>> Question......... is it true that RFID chips in passports and credit
>> can be scanned and read by thieves walking past you?  If yes, how does
>> foil that activity beyond using foil?
>> thanks to you traveling contesters,
>> Charles Harpole
>> k4vud at hotmail.com

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