['68OrangeSunshine]

Mr Beast, I seem to recall a device [black box] that was cut-in to the coax of one side of a twin mirror mount -- which by tuning a variable capacitor -- could sweep the focus of the bi-polar pattern into a directional array. The nominal radiation of ''rabbit ears'' was a figure eight, but changing the signal could make it cardioid, and also onmidirectional.
For on-highway use, the fore-and-aft signal of the bidirectional set up is probably best, but a variable sweep function is interesting.
Is there more to it than just a variable capacitor? I remember proprietary black box devices being available, some decades ago.