going back to the darlington thing for a moment, a darlington has a beta (current gain) of (betaQ1)*(betaQ2). so for a darlington made with a pair of 2N3904 transistors with a beta of 100, the beta becomes 10,000. the miller capacitance is beta times BC junction capacitance (which for a 2N3904 is 8pf). so, the darlington would have a miller capacitance of 10,000*8pf or 80nF, which has a reactance of 0.02 ohms at 100Mhz, which means the RF bypasses the base almost completely, and the transistor will not amplify it.
as for efficient antennas, google "j-pole antenna". a very efficient antenna is a better solution than an amplifier. an amplifier uses power, dissipates heat, and can be very cranky about it's load (as well as generating unwanted harmonics that can get you in deep doo-doo with whatever alphabet agency governs the airwaves in your country).