WiNRADiO AX-31B Planar Log-Periodic Antenna

Note: This product has been superseded.
AX-31B  Planar Log-Periodic Antenna

The AX-31B antenna is a compact VHF/UHF directional antenna with an in-built amplifier, which provides a low-cost alternative to conventional VHF/UHF antennas (for example discones), especially for indoor professional and amateur applications.

This log-periodic antenna is constructed on a high-quality fibre-glass substrate, with a 20dB amplifier directly mounted on the substrate, together with other surface-mount circuitry and a standard 9V PP3 type battery holder. A power switch is provided directly on the antenna.

The antenna is ideally suited for reception of VHF/UHF point-to-point communication where its directional characteristics can significantly improve rejection of interfering signals.

In professional applications, this antenna is ideally suited for EMC pre-testing, surveillance and monitoring.

The antenna covers a frequency range of 230 to 1600 MHz (a much wider frequency range can be received with reduced gain).

AX-31B Antenna with supplied cable

The AX-31B antenna package includes a 2 meter (6.5 ft) cable with an SMA connector for the antenna and a BNC connector for the receiver. Battery is not included.

While designed to be entirely general-purpose and performing well with any third-party equipment, the WiNRADiO AX-31B Planar Log-Periodic Antenna is especially suitable for WiNRADiO 1000/1500/3000 Series of receivers.

The antenna is designed for indoor reception. Its small footprint, the size of an A4 sheet of paper (11.5" by 8.5"), conserves space and makes concealed installation possible, if desired. The antenna is lightweight and installation can be achieved within minutes using double-sided adhesive tape.

AX-31B Antenna
Mount it on a wall...
AX-31B Antenna
...on glass...
AX-31B Antenna
... hide it anywhere!


The antenna has received excellent reviews in several publications:

Radio and Communications

"One common problem with most active antennas is their susceptibility to overload and intermodulation. I was pleased to see that this is not an issue with AX-31B."

"While I was experimenting with tuning to various frequencies and connecting it to various radio equipment I have at home, I also thought it may be an interesting idea to try it with my TV. The result was absolutely stunning... the unit doubles up as the finest indoor TV antenna I have ever seen!"

  Complete review in PDF format.

Monitoring Times

"Exhibiting decent gain, acceptable noise figure, and high overload immunity, it works well in the upper VHF/UHF land mobile frequencies, and its low profile invites unobtrusive placement next to a wall or window. "

"... for the new genre of wideband scanners which tune down into shortwave frequencies, the AX-31B offers significant improvement over the factory-supplied whip, and since those scanners commonly have just one antenna port, the AX-31B can be that one antenna."

  Complete review in PDF format.

Popular Communications

"It's construction - even though it's designed for indoor use only - is high quality throughout."

"I found many excellent uses for the WiNRADiO AX-31B antenna; it's stealthy, has excellent amplifier gain and forward gain and will certainly outperform that rubber-duck antenna that came with your handheld or the telescoping whip antenna that came with your base scanner."

 Complete review in PDF format.

Technical Specifications
Type Log-periodic Dipole Array with amplifier
Frequency range 230 to 1600 MHz
Antenna Forward Gain 6.0 dBi (free space)
Amplifier Gain 20 dB
Amplifier Noise Figure 3.8 dB
Amplifier IP3 25 dBm
Primary Sensitivity E-field
Polarization Horizontal or vertical (depending on mounting)
Usage Receiving only
Impedance 50 ohm (typ.)
Power 9V (PP3 type battery) @ 25mA
Connector SMA
Front-to-back ratio 18dB min (180 degrees from main lobe)
VSWR 1.7:1
Size 293 x 213 mm (11.5" x 8.4")
Weight 250g (9 oz)

Specifications are subject to change without notice due to continuous product development and improvement.