Application Notes

Maximal Cable Length Calculator for LZ1AQ AAA-1 Active Antenna

The length is limited by the attenuation of the cable and the receiver noise floor. If the receiver noise floor is low, a substantial length of cable ca be used.

Dipole Amplifier of AAA-1 Active Antenna

The dipole part of AAA-1 is a balanced high input impedance JFET design. It uses 2 monolithic JFET in a single case in order to have a matched pair which is needed for good balance in wide temperature and frequency range.

Some Notes about CAT Cables Used in AAA-1 Amplifiers

Here is my experience collected from several years using CATxx cable as antenna feeder

IMD Distortions in MW Band of AAA-1 Active Antenna Amplifier

Here are presented the measurements of output IMD spurs in medium wave ( MW) band: An extremely strong signal F1 and very strong signal F2. Two signal generators are combined and fed to the input of AAA-1 active antenna amplifier in small loop mode.

Filters for Wideband Active Antennas to Reject Strong Input Signals from Broadcasting Stations in LW, MW and FM Bands

The AAA1 amplifier has a very good dynamic range – it is higher than the most RF preamplifiers used in the best transceivers. But it is wideband and there are no filters at the input. Placing the antenna in a very strong filed can saturate the amplifier. This might happened if there is a very strong transmitter near the antenna – e.g. 100 KW BC MW transmitter 2 – 3 km away. The only way to reduce the interference is to use a reject filter at the input for the TX frequency. This filter must be placed between the antenna and AAA-1 input.

Receiver Front End Protection When Used with Active Antenna AAA-1

AAA-1 active antenna has very high dynamic range and its 1 dB compression point is at +20 dBm. At the output a heavy clipped signal can reach 6 V pp. This voltage is safe for the most of the conventional receivers and transceivers. This limit is reached only when there is a nearby transmitter or nearby lightning strike. Normally the total output power from 20 KHz to 30 Mhz is below 0 dBm at the antenna output.

AAA-1 is well protected at the input and does not need any special measures even when legal power TX is used. But the output voltage might be a problem for some receivers (Rx).

Radiation Patterns of 2-el. Active Receiving Phased Array for Loop and Dipole Mode

These are the expected radiation patterns using active antennas AAA-1 and VDLine kits combined in dual mode (dipole/loop) 2-element phased array…

Additional Environment Protection of the AAA-1 and VDL-1 Devices

The AAA-1 amplifier is inserted in a box which is marked as IP55 protection class. According to the standard it is dust and water protected. The standard says…

Wideband Small Receiving Loop Simplified

This is a small loop connected to an amplifier with very low input resistance e.g.3 ohms. The small loop is injecting current into this amplifier. The loop works almost in…

Reducing the Noise in Dipole Mode with Common Mode Filter

The noise in dipole mode in AAA-1 active antenna is usually higher than in the loop mode. One can make the wrong conclusion that the short dipole is a very noisy antenna…

Adding an Input Balun in AAA-1 in Dipole Mode to Reduce 2nd Order IMD Distortions when Asymmetric Signal Source (antenna) is Used

When using large loops as dipole arms with AAA-1 active antenna amplifier or totally asymmetric electric antennas such as ground plane (GP), some 2-nd order IMD distortion might occur due to asymmetric signal source combined with the strong signals…