Whichever antenna you choose, it's best put outside, reasonably high, and away from power lines and your dwelling. Next best bet is an attic crawl space, as close to the roof peak as possible. Always use coaxial cable from the antenna to the receiver; its shielding prevents electrical noise pickup from your environment, although the antenna itself remains vulnerable to nearby electrical noise.
The choice of antenna isn't really all that critical--typically, a random, 20-60 feet of wire is entirely adequate for listening between 1-30 MHz, and the coax may be attached anywhere along its length. While larger antennas with better impedance matching may provide more signal, they also provide more noise, so the net result of signal above noise is about the same.
One final note: If you are using a long antenna wire, chances are very good you will get signal overloading on your portable radio; such receivers typically have poorer dynamic range than the more professional desktop receivers, resulting in phantom signals appearing all over the spectrum. Try listening with your attenuator (DX/LOCAL) switch activated.
Our Skywire ANT02 dipole has been a favorite, serious, budget-priced, shortwave listener's antenna for decades. It can be mounted horizontally, vertically, as a sloper, or even at an obtuse angle and still provide reliable reception throughout the entire shortwave spectrum, even down to 100 kHz. As with any horizontal wire antenna, it should be erected as high above ground as practical, although elevations of only 15 feet or so have proven very satisfactory.
The PAR "END FEDZ" ANT08 is a superb listener's antenna with superior construction materials. Since it's end-fed, the coax can be shorter, attached to the close end of the wire. Its 9:1 impedance-matching transformer brings higher signal levels to your receiver.
Want to "roll your own?" The WiNRADiO WR-LWA-0130 ADP35 adapter is a weatherproof matching transformer that allows you to attach a long wire of your choice, and still have better signal transfer to your receiver.
Cramped for outside space? Don't want the neighbors to know you have an antenna? The H800 Skymatch ANT15 is an outstanding active antenna that embodies a booster amplifier to make its short (3') length sound like a 100' dipole! It is powered by a wall transformer or, for total isolation from power lines, you may install two 9-volt batteries. Its high performance is the widest frequency range of all--10 kHz through 54 MHz. The H-900 Gain Probe ANT27 has all of the features of the H-800 Skymatch but with additional gain for weak signal reception, and increased dynamic range to withstand strong-signal overload and avoid desensitization from close-by transmitting antennas
Is an indoor or radio-room antenna a necessity? Then try the MFJ 1020C ANT19 active antenna which is a handy accessory, allowing sharp signal-peaking from 300 kHz-40 MHz. It can also be used as a preselector/preamplifer for outdoor shortwave antennas.
The AOR WL500 ANT24 amplified window antenna provides 3.5-30 MHz reception when mounted either in a window or suspended. It is powered either by a nine-volt battery or an external power supply (neither included), and its 2' diamond shape is easily accommodated in convenient locations.
Want to null out that indoor interference? The AOR LA380 ANT44DS loop offers professional performance it features an internal high-gain amplifier (20dB for 10kHz-250MHz) and excellent overall strong signal handling (high IP3 +10dBm) ,and a sturdy, tunable loop which can be rotated to reduce indoor electrical noise sources.
FULL-SPECTRUM ANTENNAS
Looking for extremely wide frequency coverage in one antenna? The low-profile AOR SA-7000 ANT39 vertical covers 30 kHz through 2000 MHz to match the new breed of wide-spectrum receivers, and it does it well.