"Anonymous" wrote in message
...

I am a slender fellow, about 185 centimeters tall. I wonder if I can
use _myself_ as a monopole antenna for a wearable QRP station.
(Transmitter in shirt pocket, handheld straight key, and self as
antenna.) What is my impedance likely to be?

--
-30-

Rather like one of Radium's queries, but I'll bite...

This is an interesting question because it serves to demonstrate just how
many variables are involved.

Your height would probably be best used as a quarter wavelength vertical
radiator, so frequencies around 40 MHz would seem to fit the bill.

How do you intend to couple the RF to the radiating element? Dry skin has a
relatively high resistive value although once into the squishy stuff inside
your body, resistance values fall dramatically. Are you at all worried about
how much current passes through or over the radiating element? Brings a new
meaning to the term skin effect. At 40 MHz most of the RF will want to flow
around the outside of you.

What form of insulation/isolation is used from the ground? Rubber soled
sneakers, rubber boots, platform heels? What sort of ground plane will be
used. Standing on the ground would be very different to standing on a metal
roof or sheet of corrugated iron.

What local objects or obstructions are likely to be in the vicinity?

Off the cuff, I would guess an impedence of around 1 kilohm at 40 MHz would
probably be a ball park figure. You would radiate some signal but on any of
the amateur bands I would not expect a transmission range of better than
line of sight at any frequency.

Reception of signals would be okay. Receiver front ends generally have a
high impedence so your body would make a much better match to the receiving
side of the system. Receivers are also set up to receive signals in the
microvolt range, so very little in the way of an antenna is needed. This is
why you can generally pick up stuff on a radio receiver just by touching the
centre pin of an antenna socket even when the antenna itself is
disconnected.

In reality, a four foot telescopic antenna will make a far better
transmitting and receiving device than your body at pretty much any
frequency, even without any form of matching. Use one of the ferrite toroid
miracle whip designs published on the Internet to provide a half way decent
impedence match and you could work thousands of miles under the right
atmospheric conditions.

So in theory, it is possible to use your body as an antenna. In practice, it
is inadvisable to use your body for transmitting due to the potential for
causing possible physiological damage and it will be very inefficient. Using
your body as a receiving antenna does work in theory and in practice and is
unlikely to have any harmful effects.

Mike G0ULI