Antennas

The stock whip is fine for FM and a strong local AM station. On shortwave it is fighting physics: a quarter wavelength at 6 MHz is about twelve metres, so a 60 cm whip is a tiny capacitive stub. The radio is built around exactly that. Its antenna input is deliberately high-impedance, not a 50-ohm port, and tuned for a short whip rather than a coax feed. Almost everything useful about upgrading the antenna follows from those two facts.

The cheapest shortwave upgrade costs almost nothing: a counterpoise wire. The whip borrows your hand and body as a ground reference, which is why the radio often sounds worse in a stand than held in your hand. Clip a few metres of wire to the radio’s ground and the signal and SNR on the low bands climb further than extra whip length will take them.

Start cheap: a longer whip and a ground wire

A longer telescopic whip is a real win for FM and strong MW, where it can approach a resonant quarter-wave near 100 MHz. On shortwave the counterpoise does more than the extra length, and the clip-on ground lead below is the highest-value upgrade on this whole page. For a quick boost in the field you can also clip a reel extender onto the whip — use its alligator clip, not the 3.5 mm plug, because that jack on the ATS Mini is audio out, not an antenna input. Get a whip with an SMA male base so it screws straight in.

Compact loops

A small loop is quiet and directional, which helps indoors: rotate it to null out local noise. The cheap printed-circuit "donut" is pocketable but inconsistent, and some have a measured coil flaw that leaves them working at only a handful of sharp frequencies. The passive YouLoop is the one to trust: balun-coupled, no power, and it cannot overload the radio. Its output is low, so it rewards a quiet location more than a crowded daytime band.

Active antennas: more signal, more noise

An active antenna puts an amplifier right behind a small probe, so it can lift weak shortwave out of a tight space. The Mini Whip is the classic E-field plate; a broadband active whip covers the whole HF range; the MLA-30+ is an active loop that trades a whip’s noise pickup for a loop’s quieter, directional reception on a balcony. All three need DC power fed up the coax, usually a bias-tee, often over USB. All three can overload the SI4732’s modest front end and throw ghost signals across the bands, and all feed 50-ohm coax into the radio’s high-impedance jack, so a small inline attenuator or a matching transformer can tidy things up. When strong signals start swamping everything, the radio’s own attenuator and AGC are the first thing to reach for.

Going bigger: a longwire

When you can string out a few metres of wire outdoors, an end-fed random wire through a 9:1 matching transformer is the cheap classic, quieter and stronger than any whip. One caution is specific to this radio: it overloads easily on long wires, so keep the wire modest, add a counterpoise, and lean on the attenuator if images start to appear.

The 27 MHz CB antenna

This one is sold for citizens band, and it is a resonant 27 MHz element, not a broadband shortwave antenna. On receive the radio is forgiving of mismatch, so it works as a longer outdoor element that hears other shortwave bands better than the stock whip. Think of it as a bigger whip that happens to be tuned for 11 metres, not a catch-all.

Which one for your situation

A rough guide. If you only want better FM, a longer whip is enough. If you listen indoors in a noisy flat, the YouLoop and a ground wire beat anything amplified. If you have a balcony or a garden and want maximum shortwave, the MLA-30+ or a longwire with the 9:1 transformer is the way up. Whatever you hang on it, the jack is SMA female, so the antenna end has to be SMA male.

Unplug an external antenna in a storm and when you are not listening. A static discharge through the jack can quietly deafen a portable’s front end, and clipping a lead straight onto an active antenna’s amplifier can kill it.