Sharepoint - how to open URL Field link in new window SharePoint 2013

Open in new tab is only supported in Publishing URL field. You are using the basic URL field. You need to use PublishingWebControls:RichLinkField. This will give you the "open in new window" option.

Cheers!

Since the control has a CssClass Property, you could manipulate the target attribute using JQuery. For example (not tested):

<SharePointWebControls:UrlField ID="UrlField2" FieldName="Link Button" runat="server" CssClass="item-link" />

And on the JQuery side:

$(function() {
    $(".item-link").attr('target', '_blank');
});