144-145MHz 2m Bidirectional Antenna 2m3DX2D

The best you can do to win a VHF contest except 2m high gain directional antennas is to use 2m Bidirectional Antenna 2m3DX2D in the stack for the fastest switching between directions. A single antenna is excellent to cover two opposite directions on one boom. If you are in the center of the activity stack of four antennas will give you a respectable 13.7 dBi gain in every direction.

 

What does 2m3DX2D mean?

2m – 2m band
3 – 3 elements
DX – The best performance on a DX part of the 2m band covering 144-145MHz with low SWR
2D – Two dipoles on a single boom

 

 

2m3DX2D Electrical Specifications:

Frequency Range: 144 – 145MHz
Free Space Forward Gain: 2 x 6dBi
Front-to-Back Ratio: 11.5dB
-3 dB Horizontal Beamwidth: 71.6°
Polarization: Horizontal
Nominal Input Impedance: 50 Ohms
SWR Across Entire Band: <1.2
Maximum Power Input: More than 500 W, 1500 W by order
Matching Method: Direct feed through common mode choke (current balun)
Connectors: 2 x “N”

 

2m Bidirectional Antenna 2m3DX2D Dipole1 Azimuth Radiation Pattern

 

 

2m Bidirectional Antenna 2m3DX2D Mechanical Specifications:

Number of Elements: 3
Reflector Diameter: 8 mm Aluminum tube
Dipole Diameter: 8 mm Hard Copper tube plastic coated
Longest Element: 1030 mm
Element Mounting Position: Below the Boom
Two Baluns and Connectors: Included
Boom Length: 0.82m
Boom Size: 20x20mm
Number of Boom Pieces: 1
Guy rope support: Not necessary. Strong boom
Mounting Mast Diameter: 30 – 50mm 1-1/4 – 2″ OD
Clamp: M8 Stainless Steel
Survival Wind Speed: 150km/h

 

How to use a single 2m Bidirectional Antenna 2m3DX2D in two directions?

• Use the 2-Way directional switch or single coaxial relay for the fastest switching between directions.
• Put power always in just one direction.
• Receive always just one direction at a time.
• In less than a second you will have the opportunity to switch any direction for the best reception.

 

How to use two 2m Bidirectional Antennas 2m3DX2D in four directions?

• Put the distance between antennas 1800mm
• Use the 4-Way directional switch for the fastest switching between directions.
• Put power always in just one direction.
• Receive always just one direction at a time.
• In less than a second you will have the opportunity to switch any direction for the best reception.

 

How to achieve a respectable gain in two directions with a 2m Bidirectional Antenna 2m3DX2D?

• Put four antennas in the stack.
• The stacking distance is 1475mm
• Achieved gain 2 x 13.7 dBi in two directions.
• -3 dB Horizontal Beamwidth: 2 x 76.7°
• The distance between the lowest and highest antenna is just 4425mm.
• The lowest antenna must be put at least 4m above the ground.

 

 

How to achieve a winning gain in ALL directions with a 2m Bidirectional Antenna 2m3DX2D?

• The stacking distance is 1475mm
• Put four antennas in the stack on two separate masts (in total 8 antennas).
• One mast and stack of four antennas turn in your favorite direction.
• The other stack turn  90° in the relation to the first stack and mast.
• The achieved gain will be 4 x 13.7 dBi in four directions
• -3 dB Horizontal Beamwidth: 4 x 76.7°

 

How to achieve the extra gain in four directions and spare one mast with a 2m Bidirectional Antenna 2m3DX2D?

• Put eight antennas in the stack.
• The stacking distance is 1700mm
• Achieved gain 4 x 14.6 dBi in four directions
• -3 dB Horizontal Beamwidth: 4 x 57.5°

The stacking distance of 1700mm is between the same directions antennas. That means it will be 850mm between each antenna regardless of direction. 
Put the lowest antenna at least 4m above the ground. The distance between the lowest and highest antenna is just 5950mm.
The antenna system will be very compact for easy transport.

How to use a 2m Bidirectional Antenna 2m3DX2D stack in any of the above versions?

The simplest use:

• Every direction connect to the 4-Way divider.
• For four directions you will need four dividers.
• Use the 4-Way directional switch for the fastest switching between directions.
• Put power always in just one direction.
• Receive always just one direction at a time.
• In less than a second you will have the opportunity to switch any direction for the best reception.

 

The best ultimate use:

• Every direction connect to the 4-Way divider
• For four directions you will need four dividers
• The remaining four outputs put into four linear amplifiers for transmitting. 300W per direction will be good enough
• For receiving use four receivers and four ham radio operators or four computers for decoding VHF signals.

 

Do not try to connect all antennas together to use one linear amplifier and one ham radio operator.

To check all 2m antennas look here.