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MINIBAC      tm
THE  MINIMALIST  BACKPACK ANTENNA  SYSTEM 
HF Antenna for the Micro-Light Backpacking  Enthusiast

Designed for extreme weight efficiency and radio efficiency for
HF Pedestrian Portable operation where natural supports are available.

HFPACK
SIMPLE CONSTRUCTION DETAILS AND
SUGGESTIONS ON VARIOUS FIELD CONFIGURATIONS

 
 
Minibac forms its own feedline, which is quickly assembled in the field to meet the requirements of your site and choice of style. No lossy, heavy coaxial cable, or bulky twin lead is used. Use of teflon insulated wire enables a highly efficient low impedance twisted pair feedline to be made in the field simply by twisting the wire just enough to keep it in place. The feedline is normally secured by small pieces of tape at the ends. Optionally, open wire feed can be used with some small insulators as shown.
Components of the Minibac
QTY
ITEM
2
98 FEET, STRANDED COPPER INSULATED WIRE, #26 AWG
(TEFLON INSULATED WIRE PREFERRED)
2
75 FEET, NYLON CORD, 2mm DIAMETER
4
INSULATORS
(OPTIONAL, NOT NECESSARY IF TEFLON INSULATED WIRE IS USED FOR TWISTED PAIR FEEDLINE)
2
BANANA  PLUGS
(FOR CONNECTION TO RADIO OR TUNER)
1
ROLL, ELECTRICAL TAPE (OR GAFFERS)
 

Many configurations of the MiniBac are possible.

As shown in the photo at left, the MiniBac forms a multi-band dipole using 2 supports, or an inverted-Vee with a single support.
Using a single support, such as a tree or pole, the MiniBac forms an Inverted-L with efficient counterpoise simply laid randomly on the ground or upon bushes or vegetation, using no special alignment. This antenna configuration provides a good omnidirectional pattern, with both low angle and high angle radiation. While a tuner is suggested for multiband operation, no tuner is needed for 50ohm operation on 7MHz.
Using a single support, such as a tree or pole, the MiniBac forms a Tilted-L with counterpoise raised above the ground several feet high. The elevated counterpoise method provides better radiation effiency compared to a counterpoise laying on the ground.

The antenna configuration at left, provides optimum low angle signal on 10MHz-29MHz as indicated in the direction of the beam arrow. On 3.5 through 7MHz, it is omni-directional with high angle NVIS radiation for communications within about a 350 mile radius. 
A single wire of the MiniBac forms a large Delta Loop antenna strung from a single support tree or pole. This method provides high efficiency with good directivity on 14MHz or 7MHz, requiring no tuner for 50ohm match. Using the twisted pair feedline, which can be run just above ground level, this configuration may be used with good success on other frequency bands, 18 to 29MHz, but a tuner is recommended. In addition, for 3.5 and 7MHz operation, the remaining MiniBac wire can be laid on the ground as a counterpoise, similar to the #3 Inverted-L, with the Delta-Loop and its feedline used as a vertical radiator against the counterpoise.
Ham radio operators are welcome to homebrew and use the MiniBac for personal and club use.  Non-commercial use of the MiniBac name for ham radio in connection with the antenna is  authorized. All commercial rights are reserved. Links to this site should direct to the home page http://hfpack.com
Permission for use of article or drawings should  be requested by email.

©2009, 2008, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 HFpack, Inc. All Rights Reserved.
MiniBac (tm) trademark is owned by HFPACK, INC. MiniBac is an original antenna design by Bonnie Crystal, KQ6XA.
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