- It is not a capacitive probe because of its form factor (very small surface) and because, as you rightly note, is referenced to ground.
- the transformer primary is claimed to be high impedance, but it cannot be, because of it's parasitic capacitance to ground, which cannot be eliminated. With the turns given, we can expect anything from 140 pF up.
- The zip cord impedance is not certain, but a matter of speculation, as it depends on
materials used. The slightest imbalance will make it become part of the antenna itself, so once built, nobody knows how the incoming signal is collected.
- The UNDEFINED ground reference, plus the parasitic capacitance of T1 to the ground of the common base amplifier will play havoc with local noise. This amplifier stands on a "floating" ground, but what about its power supply? In such an arrangement the type, layout and capacitance to "stake" ground will produce as many different antennas as there are different supplies that might be used.
- The common base push-pull amplifier by definition is VERY LOW INPUT IMPEDANCE. Why? This puts undue stress on the turns radio of T1 for no logical reason. Furthermore the tapped inductors on the collectors make no sense and render the circuit very prone to parasitic oscillations, which will introduce extraneous noise and interference. A simple center tap on the primary of T2 should make more sense.
To conclude, not only there is nothing on this "design" that justifies the " low noise" claim, but even elementary circuit analysis shows there cannot be any wide bandwith as well, because the parasitic capacitance of T will also create resonances with the forgotten whip inductance which is always there.....
Reason: No reason