current url?

I’m trying to build a <form>. The action= needs to come back to the same page. I’ve tried this:

$this_post_id = $wp_query->post->ID;
$form = “<form method=’get’ action=’page_id=”;
$form .= $this_post_id;
$form .= “‘>”;

But it leaves the ? mark out and won’t go to the page. Example:
Need this: https://www.example.com/?page_id=46
Get this: https://www.example.com/page_id=46

Any ideas?