GUNN diode integration

can anybody show me how to integrate a GUNN diode with a rectangular microstrip patch antenna
thanks in advance.

The problem I think is that you are confusing two not directly compatible components. A Gunn diode is an active element for an oscillator. To make an oscillator, a Gunn diode should be coupled to a resonator. Then another coupling must be done, to obtain an output from the oscillator to a transmission line.
Then, you can connect your patch antenna to the transmission line.

This is the "classical" method to do it.

If your patch antenna resonates or can be made to resonate at a desired frequency, and if your Gunn diode is designed to oscillate at the same or near frequency, you can try to directly connect your Gunn diode to the antenna.
I think nobody can tell how and to which point of the antenna to connect the Gunn. A Gunn diode is a negative-resistance element, so try to experiment: install your Gunn into a heat-sink block, so you can contact its other side with the patch antenna. Then try if the assembly oscillates at the desired frequency, and if not, change the contact position.
Many years ago I achieved a similar assembly to oscillate where I wanted, and using a small parasitic element moving on a spring above the resonating patch antenna, I created a nice FM movement sensor to pick up vibration.

Thanks for reply. I don't want to know to which point of the antenna to connect the Gunn I only want to know how to connect at a certain point i.e an example would have been very helpful. How to make that heat sink block? Which software to use?

As I wrote, you will have to experiment on how to best couple the Gunn to your patch resonating antenna.
Concerning the heat sink, I do not know how to guide heat by software. You must make an aluminum block or plate large enough to maintain a reasonable temperature of Gunn body.