Spectrum Spot | Highly directional Log Periodic Antenna

Log Periodic Antenna

A Log Periodic Antenna (LPA, for short) is a highly directional antenna capable of only receiving a range of signals for a user determined direction.

This directional capability is especially useful during a site surveillance survey. For example, after surveying ISM signals in an area using an omni-directional antenna you notice a rogue signal within your site.

To find the exact rogue signal direction and location, you must use a directional antenna. A LPA is ideal in this situation because of its high directional ability teamed with its low RF gain, to give the most accurate signal analysis.

But how exactly does an LPA work?
An antenna is known as passive if it is nothing more than a receptor or transmitter of signals and requires no external power. Active antennas include a preamplifier and/or switched baluns in their base allowing matching of the antenna's frequency sensitive low impedance to the 50 Ohm input impedance of most receivers.
Electromagnetic waves longer than 1 mm, less than 300 GHz, are known as radio waves. They are subdivided into groups, such as VHF (very high frequency) and UHF (ultra high frequency, depending on their frequency. The very longest waves usually detectable are called VLF (very low frequency) with wavelengths longer than six miles at frequencies lower than 30,000 Hz.

The log periodic antenna’s active region, the portion of the antenna which is radiating or receiving radiation efficiently, shifts with frequency. The left most element (the longest element) is active at the lowest frequency of interest where it acts as a half-wave dipole. As the frequency shifts upward, the active region shifts forward. The upper frequency limit of the antenna is a function of the right most, or shortest, element.

How directional is the LPA?
The Log Periodic Antenna design enables the antenna to receive or broadcast in a very directional pattern. To illustrate, note on the horizontal plane figure to the left. The strongest signals are broadcast or received to/from straight ahead, with minimal loss 5 dB gain maximum.

In Summary...
The Log Periodic Antenna is a very useful site survey tool. It enables surveyors to receive directional signals from fixed frequency range, allowing for finding the exact direction and strength of an impeding signal.

SpectrumSpot currently offers three models of Log Periodic Antennas:

LPA-6000 (2100 to 6000 MHz Frequency Range , 5 dB Max Gain)
LPA-2600 (900 to 2600 MHz Frequency Range , 5 dB Max Gain)
LPA-1000 (400 to 1000 MHz Frequency Range , 5 dB Max Gain)

Each model includes a Type N patch cable, and a non-conductive handle for hand-held operation.
We offer both models for sale or rental.

LPA Active Region

LPA Balun location

LPA-6000

$139.00

LPA-2600

$149.00

LPA-1000

$169.00

Available for Sale!

Our LPA-6000 is our most popular Log Periodic Antenna model featuring a frequency range of 2,100 to 6,000 MHz, and a 5 db maximum gain.

Ideal for use with 802.11 a/b/g/n site surveys, which are located in the 2.4 GHz and 5.3/5.8 GHz bands.

Accessories include a 3-foot Type-N RF Cable, and a non-conductive handle.

Available for Sale!

Our LPA-2600 Log Periodic Antenna model features a frequency range of 900 to 2,600 MHz, and a 5 db maximum gain.

Ideal for use with ISM 900 MHz site surveys, which include cordless phones. Also useful for PCS cellular antenna peaking.

Accessories include a 3-foot Type-N RF Cable, and a non-conductive handle.

Available for Sale!

Our LPA-1000 Log Periodic Antenna model features a frequency range of 400 to 1,000 MHz, and a 5 db maximum gain.

Ideal for use with UHF (HDTV), HD Radio, RF-ID, or ham radio signal peaking. Also capable of receiving public service bands and legacy cellular signals.

Accessories include a 3-foot Type-N RF Cable, and a non-conductive handle.