Peter Waters G3OJV, from Waters and Stanton takes a further look at this antenna design and shows some typical bandwidths and VSWRs.
Ready made designs from MyAntennas are available from the Waters & Stanton web site. Check out
https://hamradiostore.co.uk/myant-efh...
We reckon this antenna design is a better option than the G5RV and a lot easier to feed.