John,

The most power-efficient antenna which will fit into a loft is the so-called
magnetic loop.

A loop, 2 or 2.5-metres square, or a circular or broad rectangular loop of
the same perimeter, made with 25mm plumbers' copper pipe will work
reasonably well at frequencies as low as the 160m band.

The greater the area enclosed by the loop and the greater the conductor
diameter, the greater the efficiency.

A remotely-controlled, slow-motion, vacuum tuning capacitor (1000pF for
160m) can be expensive. But capacitors rapidly get progressively much
smaller on the 80 and 40m bands, etc. A range of three bands, eg., 80, 40
and 20m, can be covered with one capacitor.

Very high efficiency, comparable with a 1/2-wave dipole can be acheived at
the higher frequencies within a much smaller space.

Whether you make one or purchase one, or just amuse yourself with figures
you can compare performance versus dimensions by downloading program
MAGLOOP4 from website below. Download in a few seconds and run immediately.
----
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

John- must second Reg- for an antenna for 20-10 meters. AEA used to make
such an antenna (cant remember the name, but think now made by MFJ. As
to higher freqs (dont laugh too hard) a friend, in K.Falls, OREGON
lived in an apartment with a loft - placed a rotator up in it, with a
combination 3 element 2 meter quad, nested inside a 2 element 6 meter
quad. One caviat, tho, make sure that if it is insulated (the loft),
that no alumiuium foil is on it for a vapor barrier! (makes a great
faraday shield!) Such an antenna is indeed worthy, as he worked ZL/VK,
as well as the east coast during f2, as well as multihop openings on
Eskip! one other thing to consider is , if you have ground fault
outlets, they are suceptable to RF tripping them, as many have found
out! As info-- Jim NN7K


Reg Edwards wrote:
John,

The most power-efficient antenna which will fit into a loft is the so-called
magnetic loop.

A loop, 2 or 2.5-metres square, or a circular or broad rectangular loop of
the same perimeter, made with 25mm plumbers' copper pipe will work
reasonably well at frequencies as low as the 160m band.

The greater the area enclosed by the loop and the greater the conductor
diameter, the greater the efficiency.

A remotely-controlled, slow-motion, vacuum tuning capacitor (1000pF for
160m) can be expensive. But capacitors rapidly get progressively much
smaller on the 80 and 40m bands, etc. A range of three bands, eg., 80, 40
and 20m, can be covered with one capacitor.

Very high efficiency, comparable with a 1/2-wave dipole can be acheived at
the higher frequencies within a much smaller space.

Whether you make one or purchase one, or just amuse yourself with figures
you can compare performance versus dimensions by downloading program
MAGLOOP4 from website below. Download in a few seconds and run immediately.
----
.................................................. .........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. .........