By: Daniel Grunberg (ce369@FreeNet.Carleton.CA)
Date: Aug 8, 1996
Original source: Usenet's rec.radio.shortwave

Modern shortwave receivers, particularly modern portables, tend to be very sensitive. Modern shortwave receivers most often are intolerant of overly strong signals, even strong signals well away from the frequency being tuned. For example, a local, strong MW station might overload your receiver's front-end. The result could be images all over the SW bands, or it could be an apparent lowering of the receiver's gain.
Therefore, the best, and least costly, antenna is the least antenna that can receive what you want to receive.
I'd try the following in turn, and stop when I was satisfied with the reception I was getting.

1. The receiver's built-in antenna.

2. Some copper wire.
Up to twenty feet of wire (insulated or not) strung up as high as is convenient, inside the house. Radio Shack has a reel-up wire for this purpose (278-1374), which easily can be taken down and stored when not in use. Ask about Radio Shack's return policy, in case it doesn't work for you.

3. Grounding the receiver and using antenna 1 or antenna 2 (above).
The following grounding methods may increase the received signal-to-noise level, but they will not necessarily protect you, your house, your property, or your receiver from lightening.
Almost any sort of external ground may help.
Improvised, less-than-ideal, external ground connections have been known markedly to increase signal-to-noise ratios.

If your receiver has an external antenna connector, an external ground connection usually may be made via the sleeve of the connector's mating plug (see illustration below). Inserting the plug into the receiver's antenna connector will disconnect the receiver's antenna from the receiver's front-end. A clip lead, from the appropriate lug on the plug to the base of the whip antenna, can be used to reestablish a connection to the receiver's whip antenna.

                 ||__________
                 ||__________||0 <--- to rcvr front-end
                 ||     ^
                      to rcvr
                       gnd

You can try to eliminate the the clip lead from the plug to the whip antenna by cutting the antenna plug. What remains of the long part near the wire terminals (which were not drawn on the left part of the figure below) should be long enough to makes a non-intermittent ground connection when it is inserted into the radio's antenna jack, but should not be long enough to operate the antenna jack's switch and disconnect the antenna.
The following figure shows what I mean.
The figure is not to scale, so no dimensions should be inferred from it. [Actually, since I haven't tried cutting a plug, I don't know what the dimensions should be.]

                 ||______                    ____
                 ||______                    ____||0 
                 ||   ^                        ^
                     insert                 throw   
                     this part              this part
                     in receiver's          away
                     antenna jack

The best way to ground your reciever is to connect its ground to a ground rod (Radio Shack has them, but I don't know the catalog number) driven into damp soil, as near to the receiver as possible.
The next best external ground connection is to a ground clamp mounted on a metal *cold* water line. Ground clamps and ground rods often can be found in the electrical supply section of your local hardware store.
Less satisfactory external ground connections may be made (in the USA anyway) to a #10-24x1.5" screw or a #10-32x1.5" screw that you have pushed into the small round ground-pin on a 120 VAC outlet.
Don't use the wall outlet ground unless you know exactly what you are doing and you have verified that the outlet has been wired correctly.

The diagram below is meant to represent a 120-VAC, 60-Hz, grounded outlet like those used in all but the oldest house wiring in the USA. The outlet has two parallel openings. Although the parallel openings are of roughly the same size, it can be seen that one of the parallel openings, the one shown on your left in the diagram, is slightly longer than the other one. The outlet has a third opening, the lowest one on the diagram, that is shaped differently and is smaller than the other two.

                         AC Power Socket
                         ________________
                        /                \
                       |                  |
                       |   ||             |
    Larger        -->  |   ||        ||   | <- Smaller parallel
     parallel opening  |   ||        ||   |            opening
      (AC-return)      |   ||        ||   |       (117-VAC)
                       |                  |
                       |        ()        | <- Smallest opening
                       |                  |       (ground)
                        \________________/

If the outlet was wired properly, the connector behind the smaller parallel opening is wired to the 117-VAC bus, the connector behind the larger parallel opening is wired to the AC-return bus, and the connector behind the smallest opening is wired to the house ground.
Before you make a ground connection to the smallest opening, the outlet should be tested. A simple way to test the outlet, is to plug an AC-outlet Analyzer, Radio Shack 22-101 (or equivalent) into the outlet. Read and follow all of the instructions and safety material that come with the outlet analyzer.

4. A convenient length of wire, dropped out of a convenient window.
The wire may be insulated or not. Weigh it down with a washer or two. A length of fine magnet wire (Radio Shack 278-1345) used this way might be a reasonable "invisible" antenna for apartment dwellers.
Try this antenna with and without a ground.
Outdoor antennas should be disconnected and grounded when not in use.

5. An end fed horizontal outdoor length of wire, used with a ground (see 3 above).
Radio Shack sells a reasonably priced kit (278-758) with wire, insulators, and a window feedthrough. The wire can be any convenient length, or you can research the project ("Build Your Own Shortwave Antennas" by Yoder, is available from Grove Enterprises and others).
Again, outdoor antennas should be disconnected and grounded when not in use.

6. Check your receiver switches.
If your receiver seems to perform worse with the outdoor antenna than without it, you may want to consider using either the LOCAL position of the receiver's LOCAL/DX sensitivity switch, an external atenuator, a filter, or a preselector between your antenna lead and the antenna plug.

Please be assured that I do not work for Radio Shack, MT, or Grove Enterprises. My only interest in Radio Shack or Grove is as a customer. My only interest in MT is as a subscriber.

Dan Grunberg
Kensington, Maryland, USA