What is a Log-Periodic Antenna?

Log-periodic antennas or LPDAs are directional multi-element antennas designed to operate over a broad range of frequencies. It includes a pair of metal pairs or dipole elements. Each element vibrates at its own frequency and the overlapping resonances allow the antenna to operate within wide ranges of frequencies.

How Handheld Log-Periodic Antennas Help Locate Signal Sources

Log-Periodic can be applied in various fields, such as:

RF Signal Direction

Case Study: Hand held log-periodic antenna can be use to measure the signal strength. Triangulation of this information with other receiver points provides operator with a very precise location of the illegal transmitter.

Sample Data: Assume the handheld antenna picks up a strong signal at 2.4 GHz. The signal strength at 90° is -60 dBm, while that at 180° is -40 dBm. With this data, it is easy to pin the direction, and when combined with other sensor data, the location of the transmitter can be pinpointed within a 200-meter radius.

Telecommunication and Satellite Dish

In telecommunication, handheld log-periodic antennas can be utilized to assist the engineer in the alignment of satellite dishes. These kinds of antennas detect and verify the strength and quality of the signal received from a satellite to ensure the dish is pointed correctly.

Military and Defense

Use Case: The military forces usually track and intercept a number of signals by using handheld log-periodic antennas.

Example Data: A handheld log-periodic antenna is used to track an enemy radar operating at 3 GHz. After several measurements, the antenna detects a signal strength of -65 dBm at one location and -50 dBm at another. Using this data, the military can triangulate the radar’s position and plan their next move.

Step-by-step process

When you’re using a log-periodic antenna to find a signal source, it usually requires going through a series of important steps to make sure the results are accurate.

Log-periodic antenna integration with signal analysis instruments

Attach the handheld log-periodic antenna to your signal analyzer, VNA, directional power meter and other instruments. Ensure that the antenna is properly connected to the measurement equipment, typically through a coaxial cable. Then, ensure the instruments are powered on and calibrated to the appropriate frequency range based on the signals you’re analyzing.

Use the log-periodic antenna to point the signal direction

• Choose a location free from obstructions and interference to ensure optimal performance.
• Securely mount the LPDA antenna on a mast or pole, ensuring stability and proper alignment.
• Accurately align the LPDA antenna to the desired direction for maximum signal strength. Rotating or moving the antenna to find the direction where the signal is strongest.
• Conduct signal tests and adjustments to optimize performance across the intended frequency range.Make necessary adjustments to antenna settings or orientation for improved reception or transmission quality.

Key Considerations When Using a Handheld Log-Periodic Antenna

When using a log periodic antenna, for best results and precise signal detection it is important to take into account multiple factors.

• Frequency Range: LPDAs operate over a wide range of frequencies, but the specific range varies depending on the design of the antenna. They are designed to cover multiple frequency bands without requiring adjustments or tuning.
• Gain: LPDAs typically have a moderate to high gain, with ranges from 5 to 15 dBi. The Arrow LPDA provides up to +12dBi gain.
• Site Selection: When using LPDAs for fixed applications, choose a location free from obstructions and interference.
• Cabling: Use high-quality coaxial cables and connectorswith the correct impedance (typically 50 ohms).
• Interference: Be aware that LPDAs canbe sensitive to interference from nearby sources.
• Environment: Be aware of environmental factors like buildings and trees that can affect performance.
• Distance: Signal strength can decrease with distance; the range varies depending on the specific LPDA. The Arrow, for example, has a range of over 5 miles.

RFecho: a Reliable Log-Periodic Antenna Supplier

RFecho is a company known for crafting high-performance antennas like log-periodic antennas. They offer a range of antennas that cater to various needs such as standard gain horns and reflector antennas, in addition to planar antennas.

Handheld log-periodic antennas are powerful tools for RF professionals needing precise directional signal location and wideband reception in a portable format. RFecho stands out as a trusted supplier, offering high-performance log-periodic antennas designed to meet diverse needs.

References

[1] SRFS Teleinfra. 2024. Log Periodic Antenna (LPDA Antenna): Applications, Advantages, and Installation.

[2] Alex Baker. 2021. Log Periodic Antennas, or Where to Put Your Arrow

[3] Peter Joseph Bevelacqua. 2008. ANTENNA ARRAYS: PERFORMANCE LIMITS AND GEOMETRY

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