by Guy Atkins
This is another clever accessory from Kiwa Electronics that makes me wonder why didnt I think of that? While it wont fit in your average shirt or pants pocket, it can be tucked neatly out of the way in a large coat or parka.
The Pocket Loop is an air-core antenna designed to improve reception of portable receivers. The antenna elements are made of copper-coated spring steel wire, otherwise known as piano wire. Collapsed the loop measures 4 x 5 x 3 inches, but it will easily spring to life a full 12 inches in diameter. The wire elements have sufficient tension to support themselves, yet are flexible enough to collapse - again and again - into a compact package for transport. The entire assembly appears sturdy enough for many years of regular use.
Signal transfer to the receiver is done by a special coupler, or by a direct cable connection. The coupler is for portable receivers having a shortwave whip antenna and/or an internal ferrite bar antenna. The coupler is placed against the outside of the receiver case (Velcro fasteners provided), near the ferrite bar antenna, or over the end of the whip antenna if shortwave enhancement is desired. The supplied direct cable is used with communications receivers having a high-impedance (hi-Z) antenna input. The Pocket Loop cannot work with a 50 ohm antenna input.
The antennas front panel tilts forward for easy operation and access to the tuning range switches (small DIP switches). Power requirements are very low at 12 ma via a 9 VDC battery, so the loop should run a long time before battery change is needed. Frequency coverage is from 530 kHz to 23 MHz in four ranges of 530-1800 kHz, 1.8-7 MHz, 5-20 MHz, and 18-23 MHz. The antenna has a built-in noise generator to aid in the tuning of signals, and this feature really adds to the easy operation of the Pocket Loop. The loops internal amplifier is quiet and has good gain, while the sharp tuning helps the loop resist overloading.
I have used the loop with a GE SR II for mediumwave, and an AOR AR7030 for shortwave and mediumwave reception. The results were very good with both receivers, and an added bonus is the capability to null local noise sources by careful positioning of the Pocket Loop. On almost all shortwave signals, the loop outperformed a 45 foot long randomwire antenna, but couldnt compete with the serious outdoor antenna I use for tropical band DXing (an unrealistic expectation for a small portable antenna!). For mediumwave when using the special coupler and the Superradio II, the difference was sometimes dramatic. Signals I could barely hear at all with the ferrite rod antenna became easily readable at good signal levels with the Pocket Loop.
The Kiwa Pocket Loop makes an excellent accessory for the radio hobbyist or traveller. It costs $120 plus shipping direct from Kiwa Electronics, or it can be purchased through the major hobby mailorder outlets.