M2 2M HO LOOP User manual

M2 Antenna Systems, Inc. 4402 N. Selland Ave. Fresno, CA 93722
Tel: [phone] Fax: [phone] Web: www.m2inc.com
©2015 M2 Antenna Systems Incorporated 08/29/12
Rev.03
Model .........................................6M HO LOOP
Frequency Range.......................50 To 50.3 MHz
Gain, Typical @ 11 ft..................6.3 dBi @ 25 deg.
Gain, 2 Stack @ 40 & 52 ft. .......10.3 dBi @ 6 deg.
Polarity ......................................Horizontal
Impedance .................................50 Ohms, Unbalanced
Power Handling..........................800W, 1.5 kW stacked
Feed Connector..........................SO-239
Mounting.....................................3/8-24 or 1-1/4”-2”
Vehicle Mounting Height ............30” or more
Stacking Distance ......................9ft to 12ft
Maximum Element Length..........29-1/2”
Wind Area...................................0.1 sq ft.
Weight ........................................2 lbs.
M2 Antenna Systems, Inc.
Model No: 6M HO LOOP
FEATURES:
Our 6M HO Loop is the result of a continued development of reduced size, omni-directional horizontally polarized loop-style
antennas. This new design is easy to match in any situation. Performance is better than anything in its class and its design makes
it immune to nearly all weather conditions. Power handling is often a problem with small loops but this design can handle 800 watts
with ease and a stacked pair can easily handle 1.5 kW. The patterns contained in the manual will give you a good idea of how well
the 6M HO Loop will perform in your system.
As with all horizontally polarized antennas, performance is usually tied to height above ground but even at ten feet the HO Loop
yields an amazing 5.9 dBi at an angle of 27 degrees. Mounted on a vehicle at eleven feet above ground, the gain jumps to 6.3 dBi at
25 degrees. Stacked for base or portable use, twelve foot spacing is optimum. Note that the gain jumps over 3 dB for a stacked pair
of these unique antennas, yielding as much as 10.3 dBi!
Physically the HO Loop is 29.5 inches square with a wind area of just 0.1 square foot. The 3/8” diameter tubing keeps it light but
plenty rugged for mobile operation. Our precision machined aluminum feed block is sealed and potted with silicon gel for extreme
reliability and low loss. The feed block slides on the tubes for frequency adjustment and the shorting bar adjusts for a perfect match
into 50 ohm feedline. Two HO Loops can be stacked using a coaxial power divider.
Optional items include our line of lightweight aluminum mobile masts and our “Big-Foot” heavy duty magnetic base. We also
offer coaxial power dividers and phasing cables for stacking HO Loops.
SPECIFICATIONS:
*Subtract 2.14 from dBi for dBd

6M HO LOOP ASSEMBLY OVERVIEW

6M HO LOOP ASSEMBLY MANUAL
1. Insert the HO Loop tubes into the center insulator.
Install screws and locknuts and tighten.
1
1. Slide on (1) support clamp and center it at 2-1/4” on
to the white center insulator. Install a 1/4-20 X 1/4
set screw into support clamp block and tighten gently.
2

6M HO LOOP ASSEMBLY MANUAL
1. Install the 1/4-20 X 1/4” set screws in the
feed block assembly and slide onto the
tubes. Carefully align the HO Loop halves
and tighten the set screws gently.
2. Install the 1/4-20 X 1/4” set screws in the
shorting bar. Slide shorting bar on to HO
Loop tubes and tighten the screws gently.
3
4
1. Position feed block assembly and shorting
bar to the starting dimensions. Refer to the
tuning detail page for more information.

6M HO LOOP ASSEMBLY DETAILS
5
6
1. Attach the second support clamp on one
end of the 3/8” support tube. Install 6-32
screw, locknut and the 1/4-20 X 1” bolt on
the support clamp block.
1. Connect the other end of the support tube to
the other support clamp block with the 6-32
screw and locknut .
2. After final tuning attach the lower support
clamp to the mast, adjust the loop to level
position and tighten all hardware.

6M HO LOOP BASE MOUNTING DETAIL

6M HO LOOP TUNING DETAIL
For base station installations, objects such as towers, large diameter masts, trees, roofs or buildings
near the HO Loop can cause some detuning. Be aware that some tuning of the HO Loop or HO Loops
in their final position or under similar conditions may be necessary. For mobile installations, tune the
HO Loop in its final position on your vehicle.
When tuning multiple HO Loops in a stacked array, tune each HO Loop individually and recheck them in
their final positions. After individual tuning and testing, add the phasing lines and power dividers and re-
test the complete system one final time, making fine adjustments as needed.
Note: Be sure to reverse one feed block to account for the 180° phase shift in the 6M HO Loop 2
Port Power Divider. See “Mounting and Stacking Options” for more information.
BASIC TUNING
Be sure the feed block assembly is set to the starting dimension in figure 4. This dimension controls the
FREQUENCY. Likewise, ensure the shorting bar is set to the starting dimension provided. The short-
ing bar position controls feed point IMPEDANCE, and also has a small effect on frequency.
Tune the frequency first by adjusting the feed block assembly. Increasing the dimension will lower the
HO Loop in frequency; decreasing it will raise the frequency. Once the HO Loop is at the desired fre-
quency, make small adjustments to the shorting bar for best match. After tuning is complete attach the
support tube as shown and tighten all hardware.
REMEMBER: HORIZONTALLY POLARIZED ANTENNAS ARE AFFECTED BY THE GROUND SO
THE HIGHER YOU GET YOUR HO LOOP, THE BETTER. The ground can be your friend as well,
providing as much as 6 dB additional ground gain at some angles above the horizon. That angle is de-
fined by the frequency and height above ground. At one wavelength (236” at 6 meters), the typical an-
gle of maximum radiation will be about 14 degrees. At two wavelengths, the angle is 7 degrees and at
four wavelengths the angle is 3.5 degrees. Net gain improves with height because the pattern hits the
ground at a shallower angle, giving up less energy to the ground.
In most mobile installations 10 to 11 feet is about the practical limit for most driving conditions. The HO
Loop can be tuned to work as low as 18" above a vehicle roof with some compromise in performance.
However, you will find more people to talk to and more DX if you can get the HO Loop up to at least the
10 foot level.
POWER CONSIDERATIONS
An HO Loop can handle up to 800 watts and a stacked pair can handle up 1.5 kW. Users often report
long distance QSO’s using HO Loops and modest power. We hope you enjoy your new HO Loop and
please keep an ear out for those rare but wonderful 6 meter openings to other parts of the world!
M2ANTENNA SYSTEMS, INC.
4402 N. SELLAND AVE.
FRESNO, CA 93722
[phone] FAX: [phone]
www.m2inc.com Email: [email protected]

MAST MOUNTING OPTIONS
HEIGHT ABOVE
GROUND
GAIN ANGLE OF
RADIATION
8 FT
MOBILE
4.74 dBi 33°
12 FT
MOBILE
6.54 dBi 22°
30 FT
BASE STATION
6.64 dBi 9°
50 FT
BASE STATION
6.84 dBi 5°
SINGLE 6M HO LOOP
PERFORMANCE
36” MOBILE MAST
(SOLD SEPARATELY)
CUSTOMER SUPPLIED
MAST (1-1/4” - 2” DIA.)

MOUNTING AND STACKING OPTIONS
HEIGHT ABOVE
GROUND
GAIN ANGLE OF
RADIATION
8 FT AND 18 FT 8.03 dBi 17°
8 FT AND 20 FT 8.47 dBi 16°
20 FT AND 32 FT 9.96 dBi 10°
40 FT AND 52 FT 10.54 dBi 6°
2 STACKED 6M HO LOOP
PERFORMANCE
SHOWN IS AN EXAMPLE OF A BASE
STATION SYSTEM OF 2 STACKED AND
PHASED 6M HO LOOPS
CUSTOMER SUPPLIED
MAST (1-1/4” - 2” DIA.)
NOTE:
A 180° REVERSAL OF ONE FEED BLOCK
IS NECESSARY TO ACCOMMODATE THE
EXTRA HALF WAVE (λ/2) OF COAX IN THE
LONG PHASING LINE OF THE 6M HO
LOOP 2 PORT POWER DIVIDER.
PARTS NEEDED:
 (2) 6M HO LOOPS
 6M HO LOOP 2 PORT POWER DIVIDER
(OMITTED FOR CLARITY)
Order online at http://www.m2inc.com

MOBILE MOUNTING OPTIONS
SHOWN IS AN EXAMPLE OF MOBILE
HO LOOP MOUNTING
(YOUR INSTALLATION MAY DIFFER)
CAUTION:
DEPENDING ON THE MAKE AND MODEL OF YOUR VEHICLE AND THE THICKNESS AND COMPOSITION
OF THE VEHICLE BODY, ADDITIONAL GUYING OR SUPPORT MAY BE NECESSARY.
PARTS NEEDED
 6M HO LOOP
 36” ALUMINUM MAST
 “BIG-FOOT” MAGNET MOUNT
Order online at http://www.m2inc.com

6M HO LOOP PARTS & HARDWARE
DESCRIPTION ........................................................................................ QTY
HOLOOP TUBE (BENT) 3/8” OD............................................................. 2
SUPPORT TUBE, 3/8” ............................................................................ 1
FEED BLOCK ASSEMBLY ...................................................................... 1
SHORTING BAR, 1/2” X 1/2” X 2-1/2” ..................................................... 1
CENTER INSULATOR, 3/4” UHMW ........................................................ 1
SUPPORT CLAMP, 1/2” X 1” X 2-1/4” ..................................................... 2
HOLOOP UNIVERSAL MAST BRACKET................................................ 1
UNI-CRADLE, (M2AMC0176).................................................................. 2
U-BOLT, 2” HINDLEY .............................................................................. 2
ASSEMBLY MANUAL.............................................................................. 1
HARDWARE:
BOLT, 3/8-24 X 1”, SS ............................................................................. 1
LOCKNUT, 3/8-24, SS............................................................................. 1
BOLT, 1/4-20 X 1”, SS ............................................................................. 1
BOLT, 1/4-20 X 3/4”, FLAT HEAD PHILLIPS, SS.................................... 1
SET SCREW, 1/4-20 X 1/4”, SS .............................................................. 7
LOCKWASHER, 1/4”, SS......................................................................... 4
NUT, 1/4-20, SS....................................................................................... 4
SCREW, 6-32 X 1-1/4”, SS ...................................................................... 2
SCREW, 6-32 X 1”, SS ............................................................................ 2
LOCKNUT, 6-32, SS................................................................................ 4
ALLEN WRENCH, 1/8” ............................................................................ 1
M2ANTENNA SYSTEMS, INC.
4402 N. SELLAND AVE.
FRESNO, CA 93722
[phone] FAX: [phone]
www.m2inc.com Email: [email protected]