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I am designing a power amplifier with RA60H4047 UHF module. I am designing the schematic for driver circuit. It is a two way power amplifier (the transmission and reception paths are different.)

Normally people design with a relay in both input and output to avoid mixing receive signal from the antenna with the RA60h transmission.

A relay creates chatter and I think a diode on the output of RA60 should be good enough to prevents mixing the signals.

The output of the RA60H4047 is 60-80 W based on bias current and frequency range (400-470 MHz).

What diode can I use for this application?

The voltage I am providing for 60 W output is 13.5 V.

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  • \$\begingroup\$ Please provide technical justification for using a diode and maybe provide the proposed schematic. \$\endgroup\$
    – Andy aka
    Commented Mar 14, 2023 at 9:21
  • \$\begingroup\$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. \$\endgroup\$
    – Community Bot
    Commented Mar 14, 2023 at 9:45
  • \$\begingroup\$ Diode is to make amplified transmission signal from RA60H uhf module to block reverse voltage \$\endgroup\$
    – Asif Rahman
    Commented Mar 14, 2023 at 9:46

1 Answer 1

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You can't just put a diode in to isolate the transmit and receive signals, the diode needs to act as a switch and there may need to be more than one diode.

The diodes used in this application are known as PIN diodes (Positive/Intrinsic/Negative). PIN diodes can act as fast switches at high frequencies.

In T/R switching, a PIN diode is placed between the transmit amplifier and antenna, and often another is placed across the receive input such that when transmitting a bias voltage is applied to both diodes switching them on, with one passing the transmit power to the antenna and the other shorting the receive input to ground to keep any transmit power from damaging the receive front end.

There are a number of ways to do PIN diode switching, in some cases quarter wave matching sections are used to create high and low impedances to improve the switching characteristics. You can see some information on using PIN diodes here.

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