QRP Station > Antennas

Calculation of broadband TTFD (T2FD) for HF from 1 to 50 MHz

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US5LOC:
http://goryham.qrz.ru/ant/7/ttfd.htm

LU6DO:
Hello my friend. Is possible translate to english the details of antenna
http://goryham.qrz.ru/ant/7/ttfd.htm
73 & Dx de LU6DO

SM5JAB:

--- Quote from: LU6DO on December 09, 2013, 04:47:56 UTC ---Hello my friend. Is possible translate to english the details of antenna
http://goryham.qrz.ru/ant/7/ttfd.htm
73 & Dx de LU6DO

--- End quote ---


Strictly speaking I don't think you want a TTFD for QRP-operations anyway. Its only virtue is the low SWR over a large range of frequencies. The bandwidth comes at a cost of VERY low efficiency. You lose much power into the antenna's loading resistor. At the lower frequencies it radiates only a few percent of applied power.

In a sense the antenna transforms a 100W transceiver into a QRP-rig...

DF5WW:
Hi SM5JAB,

you got right. Broadbandantennas are antennas for high Power. A lot of the power will be heat up the world, hi hi. Not really good antennas for QRP. I prefer doublets or loops with ladderline (open feeder) and a symmetric antenna coupler. Those antennas are "Multibands" and don´t lost 2much of the radiation power.

73´s, Juergen, DF5WW

ve3lyx:
MMMMMM I don't know if its so. For years I used only monobands. Even had a cushcraft A 3 on a tower 1/4 wave up. From this QTH it was always difficult. Since stringing a long wire which is a multiband as well and feeding it with a tuner I have never looked back. Best antenna at this particular QTH I have used. In fact I am taking down my inverted vee for 40M next good WX day. I am really a bit upset that all these years I avoided using a multiband antenna with a tuner and when I finally did (more or less to prove it was a waste of time) it turns out to be my top performer. I also use a beverage to receive. No noise and good sig strength. A very well kept secret.  I have come thru experience to believe that different antenna suits different QTHs
Don

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