there are a tonne of instructions on how to make magnetic loop antennas on 
the internet.  A simple google search will yield all kinds of stuff.
The thing about building it yourself is you have to have a large variable 
capacitor.  Unless you want to make a loop for one frequency using a shorted 
coaxial stub.
Copper tubing, plumming fittings and either rg58 coax, or a variable 
capacitor are what you need.
A hax saw, drill and a soldering torch are also necesary...though some guys 
forgo the soldering torch and use screws and clamps to join the sections of 
the loop.
Like I said, there are many many different articles and textual instructions 
online of how to build one of these and what materials and tools are 
required.
I haven't built one yet because I'm not all that keen on having a single 
frequency antenna for HF...because an air variable cap is rather expensive, 
and if you have the antenna outside, you have to manually tune it each time 
you change frequencies, or set up some kind of motor control.
I believe MFJ does sell a unit designed to work with magnetic loop antennas 
which includes the capacitor which goes on the antenna itself, along with a 
remote box with up and down controls to set the cap via a motor.
Not cheap though.
A square loop of 36 inches a side, will tune from 40 to 6 meters if you have 
the proper cap.

73
Colin, V A6BKX
--------------------------------------------------
From: "eric oyen" <[log in to unmask]>
Sent: Monday, October 21, 2013 11:59 AM
To: <[log in to unmask]>
Subject: Re: Small loop antennas

> does anyone happen to have the directions on how to make one of these? I =
> have checked the ARRL website under antenna handbook, and that =
> information is in a graphical format. It would be nice to add one of =
> these to my burgeoning antenna farm. :)
>
> DE N7ZZT
> eric
> =20
> On Oct 21, 2013, at 10:45 AM, Colin McDonald wrote:
>
>> I believe in the magnetic loop antennas because I've heard them on the =
> air=20
>> and have used them a little as well.
>> They perform as well as, or probably better than something like a =
> mobile=20
>> antenna or screw driver or buddy poll etc.
>> I think they can probably perform as well as a dipole in the right =
> operating=20
>> conditions and with good propigation as well.
>> They're relatively easy to build, or buy, take up little room, are =
> somewhat=20
>> directional, and lend themselves well to qrp operation if that floats =
> your=20
>> boat.
>> The key to qrp operation is to use the other guys big antenna lol.
>>=20
>> 73
>> Colin, V A6BKX
>>=20
>> --------------------------------------------------
>> From: "Jim Gammon" <[log in to unmask]>
>> Sent: Sunday, October 20, 2013 11:19 PM
>> To: <[log in to unmask]>
>> Subject: Small loop antennas
>>=20
>>> Hi Colin, I have a friend who used a copper loop antenna
>>> approximately 36 inches in diameter to conduct DX with European
>>> stations using I think 10 watts.  He lived in an apartment and
>>> was using a digital protocol but I can't remember which one it
>>> was other than it wasn't PSK 31.  Pretty amazing stuff, but each
>>> contact takes a while, kind of like it will be when we have folks
>>> living on Mars! 73, Jim WA6EKS
>>>=20
>>> ----- Original Message -----
>>> From: Colin McDonald <[log in to unmask]
>>> To: [log in to unmask]
>>> Date sent: Sun, 20 Oct 2013 22:42:00 -0600
>>> Subject: Re: interesting article
>>>=20
>>> I have yet to hear one of these actually on the air.
>>> The theory is logical, and the science supports it, but in real
>>> world
>>> performance I'm not sure how successful they've actually been so
>>> far.
>>> The key to using a tiny HF antenna is to communicate with people
>>> who have
>>> big high gain antennas hi hi.
>>>=20
>>> 73
>>> Colin, V A6BKX
>>> --------------------------------------------------
>>> From: "Howard Kaufman" <[log in to unmask]
>>> Sent: Sunday, October 20, 2013 1:59 PM
>>> To: <[log in to unmask]
>>> Subject: interesting article
>>>=20
>>> Here is a very interesting article on small HF antennas and the
>>> theory
>>> behind them.
>>> PVC pipe and fruit cans, both readily available.
>>>=20
>>> http://www.rexresearch.com/harteh/harteh.htm
>>>=20
>>>=20
>>> H T Kaufman MSW LCSW
>>> Adaptive Technology Instructor=20