Different header-top-navbar.php on the home page?

I want to create a tall banner on the homepage only, and have it much smaller on all the other pages. - since I want it above the menu, it will have to go in the header-top-navbar file.
so can I have a different one on this page - will i have to create a separate base file? if so how do i go about using it?
hope I am making sense.

Don’t create a new base.php. If you want to load a different template file, use this in base.php:

if (is_front_page()) {
} else {

You could also just add conditionals within one header template file:

    <?php if (is_front_page()) : ?>
      <h1>I'm only on the home page</h1>
    <?php endif; ?>    

ah brilliant, thanks Ben - thats all I needed!