Topband: T-antenna dimensions?

[Mike Waters W0BTU]

Now that I can hear very well (Two 2-wire bi-directional Beverages), it's time for a transmitting antenna. I want to play in the contest during January 29-31, and time is running out to put up a transmitting antenna. I don't have a tower at this time.

I have some trees picked out for a T antenna, between a section of pasture where it's easy to lay down a lot of radials. I can have a 50' vertical section.

But I'm having trouble finding what the approx. dimension of the horizontal portion at the top should be. Any advice would be appreciated!

73,
Mike Waters
W0BTU