Model No. LPD-600 Log Periodic Antenna Frequency Range: 600 MHz to 18 GHz

General Description
 
Log Periodic Dipole Array (LPDA)
The geometrical configuration of the Log Periodic antenna enables the characteristics to repeat periodically with the logarithm of the frequency.  Since the variation of performance characteristics is small throughout one period, and because of the repetitious nature of the antenna, the variation in performance will be small throughout all periods. This results in an antenna with input impedance, gain characteristic, and radiation patterns essentially independent of frequency.
 
The LPD-600 is a lightweight, medium-gain, log periodic antennas. It is designed for reception or transmission of linear polarized radio signals over the useful frequency range of 600 MHz to 18 GHz.  Precision construction of the elements results in excellent VSWR and optimal phase relationship. The log periodic array design is broadband with 50 ohm nominal impedance and a unidirectional radiation pattern. It is compact, rugged, and weather resistant.  The antenna incorporates a handle, cable strain relief, and a ¼”-20 threaded insert for mounting on a camera tripod.
 
The antenna is constructed of lightweight, copper clad PC board and corrosion-resistant aluminum providing years of trouble free performance.  It is manufactured on FR4 .063” fiberglass board, is triangular in shape, and has a transposed strip line feed arrangement which provides an end fire pattern.  The maximum gain is off the tip of the structure in the direction of the boom axis.
 
The gain of the antennas vary across the band from 0 dBi to +6 dBi. A good front-to-back ratio is maintained at about 8 to 30 db which provides a unidirectional radiation pattern useful for radio direction finding.  Representative gain, front-to-back, half power beam width and radar pattern curves are shown below.
 
Transmitting power is limited primarily by the power dissipation capability of the circuit board.  Do not exceed 1/2 Watt CW input power. Exercise caution when applying power if the antenna housing is wet.

Examples of how to use the Portable Log Periodic Antenna.
 
The log periodic antenna is linearly polarized.  Hold the antenna vertical, for vertical polarized signals.  Typically this will be a whip antenna and your signals will be vertical.  Hold the antenna horizontal for horizontal signals.  Since circular polarized signals have both polarizations it does not matter how you orient the antenna.
 
Swing the antenna back and forth in azimuth across the suspect target location and look for a maximum in the signal level.  The log periodic antenna has a broad pattern so there will not be a direct sharp peak - it will cover 90 degrees or more.  The target location will be in the middle of the broad peak.  For horizontally polarized signals, it will most likely be easier to attempt to null the signal from the back of the antenna, rather than seeking the maximum peak.
 
If the receiver has the AGC turned on it will be more difficult because the receiver tries to hold the signal level constant.  Most radios do not allow you to turn off the AGC.  If the target signal is FM it will be even more difficult with a receiver because in the FM mode most receivers use limiting to hold the level at a constant. For that reason, a spectrum analyzer will likely be a better choice for displaying the signal level visually instead of trying to hear it aurally.

You should also always keep the antenna balanced with your body (see below) due to its close proximity.  

ELECTRICAL  SPECIFICATIONS     
 
Frequency Range:                 600 MHz to 18 GHz
Radiation Pattern:                Unidirectional in the H and E
Front-to-Back Ratio:             8 to 30 dB
Power Gain:                      0 to +6 dBi
Impedance:                      50 Ohm, nominal               
VSWR:                           1.5: 1 max
Transmitting Power:                  1/2 Watt CW Max

MECHANICAL  SPECIFICATIONS   
Dimensions:                      12” X 9”
Weight:                          7 oz without cabling
Mounting                        Hand Held with ¼”-20 threaded insert for camera tripod
Material:                         FR-4, double sided 0.063 inch thick 2 oz. copper                                   
 
MAINTENANCE AND TROUBLE-SHOOTING
The design of the LPD-600 is such that little or no maintenance is required under normal usage.  The housing should be kept reasonably clean and dry and the connector must be free of any obstruction.
 
If the antenna is suspected of failure, some simple tests will usually isolate the problem.  First, visually inspect the connector at the rear and be sure the cabling is seated properly.  Any unseen damage to the connector or feed line may be revealed using an Ohm meter.  The center pin of the connector to shield of the SMA should be about 50 ohms.  Field repairs can be accomplished as necessary or return the product for service.
 
ORDERING INFORMATION
Antenna Kit:                             Model No.        LPD-600
Kit contains
           Antenna LPD-600
           Coax Cable with SMA fittings
           Waterproof Shipping Case
           Manual

Downloadable Manual in PDF form for LPD-600
                       
One year warranty on parts and labor
Specifications subject to change without notice
Printed in U.S.A. Copyright        6/18/2015
 
Ferrel Bentley:
President: Antenna Authority Inc: Phone 770-577-7969 email Ferrel@dfAntennas.com

Antenna Authority offers a wide assortment of directional, wideband antennas and other equipment used for radio direction finding and Geo location. We are experts in covert antennas, vehicles and their operation. We are also ready to design new products to meet your specific needs.