BWeq means BandWidth and somehow I think you are missing a part of that equation, the part that deals with impedances because as I remember in order to calculate voltage or current noise requires an impedance.Or some means of normalizing the measurement, usually to 50 ohms but it can be any simple or complex impedance.
The "receiver noise bandwidth" is the figure that you need - the equivalent brick-wall bandpass bandwidth of thereceiver's response. You'll get noise from the input stage(s) of the receiver and from the air (interference from artificialand natural sources, and ultimately the 2.7K background radiation from space). Also resistive losses in any cable between receiverand antenna will introduce noise too (more at higher RF frequencies). Only the resistive elements of the losses willbe at 300 kelvin. Interference may dominate if you are in a city, for instance.Point a good antenna straight up and you'll often get a noise temperature well below 300K, but also interference fromsatellites, the sun, Jupiter (again RF frequency dependent).Given the antenna bandwidth is so wide it implies you are well into the UHF bands, I think this means less interferencein general, so thermal noise will dominate.And you should use natural logs, not base 10 for that equation.... k T ln(bw)