Printed circuit doubly balanced mixer for upconverter

A doubly balanced mixer for a high frequency upconverter comprising:

• an insulated substrate;
• a local oscillator balun having a split annular first foil element on one side of said substrate and an open annular second foil element on the opposite side of said substrate;
• electrical connections interconnecting said split annular first foil element and said open annular second foil element;
• a buffer amplifier and a balun on said substrate for coupling an oscillator signal to said local oscillator balun;
• an IF balun comprising third and fourth annular foil elements juxtaposed on opposite sides of said substrate in mutual coupling relationship with each other;
• and
• RF switching means coupled between said local oscillator balun and said IF balun.

A double balanced mixer comprising:

• a source of a symmetrical local oscillator signal;
• a switching circuit controlled by said local oscillator signal;
• a source of RF signal;
• and
• a printed output circuit having a wideband response for receiving said RF signal and connected to said switching circuit for producing a narrow band IF output signal comprising the frequency difference between said local oscillator signal and said RF signal.

A double balanced mixer comprising:

• a source of a symmetrical local oscillator signal;
• a switching circuit controlled by said local oscillator signal, said switching circuit comprising first and second MESFET switches, each having a gate electrode connected to receive said local oscillator signal, an output terminal and a third terminal connected to ground;
• said first and second MESFET switches being alternately turned on and off in response to said local oscillator signal;
• a source of RF signal;
• an insulated substrate;
• and
• a printed output circuit having a wideband response for receiving said RF signal and connected to said switching circuit for producing a narrow band IF output signal comprising the frequency difference between said local oscillator signal and said RF signal;
• said printed output circuit including a printed IF balun having a first foil element, in a parallel tuned circuit, connected across said output terminals and a second foil element, in a series tuned circuit, displaced from said first foil element on opposite sides of said insulated substrate.