please tell me, is there an issue with using a "twin-lead" antenna wire for Tx monopole antenna?

 

I've seen it used in a folded dipole and can't see why it could not be used for a monopole.

 

please tell me, is there an issue with using a "twin-lead" antenna wire for Tx monopole antenna?

How would you use it? That is, do you just mean using it as the antenna itself, as the radiator, with the leads shorted?

 

One problem will be matching it to the transmitter which typically has 50Ω impedance and the twin lead which has 300-400Ω impedance. Then matching it to the antenna's impedance which is also typically 50Ω for most commercially produced transmit antennas. Which is one reason why 50Ω coax is what I preferred.

 

One problem will be matching it to the transmitter which typically has 50Ω impedance and the twin lead which has 300-400Ω impedance. Then matching it to the antenna's impedance which is also typically 50Ω for most commercially produced transmit antennas. Which is one reason why 50Ω coax is what I preferred.

I can’t tell if he is asking about using it for feedline or just as a radiator. As a radiator it would be OK given a properly designed antenna otherwise. As feedline there are many problems. Matching is one, as you mention, but the other is loss which will be very noticeable. The question is lacking information.

 

RE: SamR Imho impedance transformer 1:4 is rather simple thingy thus 300-->75 Ohm is kindershpiele. And 75-->50 is solvable thing as well, but always is question do the playing is worth the candles spent for light. So, better to use classical solutions like lambda quarter or subversion CLC, lambda half or lambda 5/8. Or if the directivity was the aim then Cantenna, allowing unite the needed with pleasant - buy the bear can, drink the dry, and use can for antenna.