Antenne til proximity læser

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Hej

Jeg har en OEM proximity læser som jeg gerne vil have lavet en antenne til
så jeg opnår en max læse afstand, problemet er at jeg intet kender til
elektronik.

Her er lidt info om læseren:

1. Introduction
The GP-8 is a low cost high performance OEM proximity reader module for use
with a simple external antenna. The module features medium read range and
small dimensions. The GP-8 also has good read range at 5 Volts, making it
ideally suited to a wide variety of applications, particularly access
control. The same basic unit can be configured to most of the common output
formats, including Wiegand and Magstripe, making it easy to upgrade existing
installations. (Kan også bruges med RS232)

3. Theory
The reader generates a 125KHz inductive field that extends some way beyond
the reader module. When a transponder is placed within the vicinity of the
reader module, it draws power from this field and providing the field is of
sufficient strength the internal microcircuits contained in the transponder
begin to function. Data is transferred from the transponder by means of
amplitude modulation in such a manner that the transponder varies the rate
at which it draws power from the field in a way that corresponds to the
internal identity code programmed in this internal memory. These changes in
field power can be detected by the reader and converted back into a copy of
the original data.

9. External Antenna
A simple experimental antennae consisting of 8 turns of 0.8mm diameter
copper wire loosely wound on a 10x10 cm former and measuring 16uH will give
a range of approximately 30cm when tuned with a 0.1uF capacitor. Ranges in
excess of 40cm can be obtained with a suitable antennae and capacitor. The
required inductance will differ if the GP8 is placed within the coil and
required values can vary from 16-17.1uH depending on the exact position. For
example a small antenna wound around the GP8 will need to be about 17uH
however a 10cm radius coil will require a value of about 16uH.
Note that the best read ranges are found when the inductance is made
slightly more than that required for resonance. Polypropylene, Polycarbonate
or Polyphenylene-Sulphide capacitors are recommended. Ensure the tuning
capacitors are capable of working continuously at 125KHz at the measured AC
voltage present on the coil (6-18vRMS) depending on coil Q. Use only low
loss capacitors.

Suitable tuning capacitors include:
Wima MKP 2 0.1 /100 VDC 15 VRMS max @ 80 `C (PP)
Wima MKI 2 0.1 /100 VDC 12 VRMS max @80 `C (PPS)
Wima SMR IOOnF100VDC (PPS)
Panasonic ECHUI H104 7 VRMS (PPS)
Evox Rifa PMRI S 104K250L4 32VRMS max @ 80 `C (PP) (0.2m/s air flow)
Evox Rifa PHE427FB6100J 43 VRMS max @ 80 `C (PP) (0. 2m/s air flow)

Mvh
HK



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