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An Example of Stripline Construction Without Circuit Etching

The Board

This is an exercise in the construction of a 923 Mhz amplifier using stripline placed on top of the ground plane. All the passive devices are made from pieces of PC board with the exception of supply and bias.

The oscillator and the amplifier are built on separate boards so the input reflection coefficient of the amplifier could be measured. It came in at 1.2. Also, the oscillator power has to be known to determine gain, which was something better than 12 db. The output power of the amp is over .6 watts with better than 50% efficiency with a 12 volt supply.

 

The Circuit

This is built around Motorola's MRF559. C1 is is a 5 by 5 millimeter snip of PC board .2mm thick with the copper clad. Using very thin board will allow you to create small capacitors with a lot of Q. This cap is over 4 pF. L1 is approximately .4 nanohenries.

I will post the Smith Chart solution to this exercise at a latter date. I'll also address methods of determining device parameters using a slotted line. The line impedances are approximate. I built this a while back and have lost track of the original documentation.

By constructing an amplifier that exceeded the gain and efficiency expected from this device demonstrates that stripline does not have to be etched to achieve performance.


The HP805C Slotted Line

Handbook of Microwave and Optical Components, Kia Chang, Wiley and Sons, Inc. isbn 0-471-61366-5

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