M2 Antenna Systems 403CP20 User manual

M2 Antenna Systems, Inc. 4402 N. Selland Ave. Fresno, CA 93722
Tel: [phone] Fax: [phone] Web: www.m2inc.com
©2022 M2 Antenna Systems Incorporated 08/17/22
Rev.00
Model ........................................ 403CP20
Frequency Range ...................... 398 To 408 MHz
*Gain .......................................... 14 dBic
Front to back .............................. 16 dB Typical
Elipticity...................................... <3dB
Feed type ................................... “T” Match
Feed Impedance. ....................... 50 Ohms Unbalanced
Maximum VSWR........................ 1.5:1 Typical
Input Connector ......................... “N” Female
Power Handling..........................1.5 kW (250W PS-I)
Boom Length / Dia .....................77” / 1”
Maximum Element Length .........15”
Turning Radius:..........................Call
Stacking Distance ......................Call
Mast Size ...................................1-1/2” to 2” Nom.
Wind area / Survival ...................0.08 Sq. Ft. / 100MPH
Weight / Ship Wt. .......................6 Lbs. / 8 Lbs.
FEATURES:
The 403CP20 is a light, medium performance circularly polarized antenna. Optimum match and gain are
between 398 & 408 MHz for the satellite band. Computer design techniques help keep spurious side lobes low down
for optimum signal to noise ratios. This antenna features the same CNC machined, O-ring and silicone-gel sealed,
driven element assemblies common to all M2 Yagi antennas. This insures years of trouble free performance
regardless of weather.
SPECIFICATIONS:
*Subtract 2.14 from dBi for dBd
M2 Antenna Systems, Inc.
Model No: 403CP20

TOOL REQUIRED FOR ASSEMBLY: screwdriver, 11/32 nut driver or wrench, 7/16” and1/2” socket or end
wrenches, measuring tape.
1. Assemble the boom using 8-32 X 1-1/4 screws and locknuts to join sections. Sections may may be swaged
to each other or use 7/8” internal splice sections.
ASSEMBLING THE HORIZONTAL ELEMENTS
2. Lay out the elements by “H” length and position as shown the DIMENSION SHEET. Start with the reflector
(longest) element. Balance it on your finger to find rough center and push on a black button insulator to about
1/2” off center. Push the element through the holes 1.937” from the rear of the boom and install the second
button, snugging it up into boom. DO NOT BOTHER CENTERING the element at this time and DO NOT
INSTALL the stainless steel shaft retainers yet. It is easier to do it after all the horizontal elements are
installed in the boom.
3. Install the 3/16” rod DRIVEN ELEMENT as you did the reflector. Then continue with the installation of the
DIRECTORS. Note that the Director Elements do not consistently diminish in length from rear to
front, so pay close attention to length and position.
4. Now begin centering the elements. Use a tape measure to EQUALIZE the amount the element sticking out
on each side of the boom. Once you have all the elements centered, sight down the element tips from the
rear comparing each side. Look for any obvious discrepancies and correct if found.
5. Stainless steel SHAFT RETAINERS lock the elements in place. They should always be used for permanent
and long term antenna installations. For portable or temporary use, the button insulators are adequate for
holding the elements and the retainers may be left off.
To install the stainless steel SHAFT RETAINERS, use thumb and forefinger to hold the retainer over the end
of the PUSH TUBE ( 3/8" x 3" tube, supplied in the kit), internal fingers on retainer dished into tube. HOLD
THE ELEMENT FIRMLY TO PREVENT IT FROM SLIDING OFF CENTER and press the retainer onto the
element end and continue until retainer butts on insulator button. Locking pliers, lightly clamped up against
opposite button insulator will help maintain center reference (if you push the first retainer too far, remove
element from boom, push retainer completely off the element, and start over). Install another retainer to the
opposite side of the element. Continue installing retainers until all elements are secured.
6. Mount the HORIZONTAL DRIVEN ELEMENT
BLOCK / ROD ASSEMBLY to the TOP of the
boom using a single 8-32 X 1-1/4" screw. Orient
the block with the two balun connectors facing to
rear.
7. Install the 8-32 x 1/4” set screws (internal Allen
head - tool supplied) into the SHORTING BARS.
Slide the bars onto the 1/8" Driven Element
Block Rods and the 3/16" driven element rod.
Position the Shorting Bars at 1/8" from the
tips of the 3/16" rods. Align the bars with each
other and tighten the set screws.
ASSEMBLING THE VERTICAL ELEMENTS
Note: The vertical element set is shifted forward on the boom by 1/4 wavelength.This increases isolation
between element planes, improving circularity and ease of phasing / matching the two element sets.
8. Repeat steps #2 through #5 for the Vertical elements, using the Dimension Sheet as your guide to lengths
and spacing.
INSTALLATION OF THE VERTICAL DRIVEN ELEMENT BLOCK DETERMINES THE CIRCULARITYOF
THIS ANTENNA. THE ORIENTATION OF THE BLOCK FOR RHC - RIGHT HAND CIRCULARITY, IS
SHOWN ON THE DIMENSION SHEET.
9. Viewed from the rear of the boom , the VERTICAL Driven Element Block mounts to the RIGHT hand side of
the boom with the Balun connectors oriented to the front. Secure with 8-32 x 1-1/4” screw. Install the
Shorting Bars as in step #7. The HORIZONTAL Driven element block mounts on top of the boom with the
feed connector and power feed through oriented to the rear.
10. Before installing the Baluns and Matching / Phasing Harness, thread 3/8” SEAL NUTS fully onto all
connectors, with the black Neoprene face of the nuts facing out. Attach Baluns and Phasing lines to the
403CP20 ASSEMBLY MANUAL

403CP20 DIMENSION SHEET

403CP20 ASSEMBLY MANUAL
10. Before installing the Baluns and Matching / Phasing Harness, thread 3/8” SEAL NUTS fully onto all connectors, with the
black Neoprene face of the nuts facing out. Attach Baluns and Phasing lines to the Driven Element Blocks and Junction
Block as shown on the Dwg. Tighten the connectors gently using a 7/16" end wrench. Once the connectors are tight,
back the Seal Nuts out and finger-tighten firmly up against the face of the connectors (or tighten gently with 1/2” end
wrench). A lot of torque is unnecessary. Depending on model and polarity, the Vertical balun may loop around another
element. This is normal. Form balun coax until it is close to the boom and secure with a nylon cable tie. Also secure the
other balun and the matching / phasing harness coax with cable ties. Ties should be snug but not crushing or kinking
the coax.
11. Use good quality coax and “N” connector for your feedline (see Installation Tips). Secure feed coax near connector on
Junction Block, to provide stress relief. Allow about 60” of coax to hang in a loop between the rear end of the boom and
the reattachment point (at least 12” beyond element tips) on the mast or crossboom. Do not route feedline to boom to
mast plate as exiting antenna here will adversely affect circular field.
12. The boom to mast plate is normally mounted to the boom at the balance point. Since the feed line represents significant
weight it is best to have it attached and fastened to the boom with cable ties before final mounting the plate. Use two 1" U-
bolts and the stainless nuts and lock washers provided. DO NOT OVER TIGHTEN. 1-1/2” and 2” U-bolts (and stainless
steel nuts / lockwashers) are provided for mounting the antenna to your NON-CONDUCTIVE mast or crossboom.
THIS COMPLETES THE ANTENNA ASSEMBLY.
INSTALLATION TIPS
13. The 403CP20 is a circular polarized antenna and creates a field in all planes or polarities. Performance DETERIORATES
SIGNIFICANTLY if it is mounted on a metal (conductive) mast or crossboom. A mast or crossboom of any NON-
CONDUCTIVE material must be used. Fiberglass is the prime choice for its strength and weather resistance. Mount the
436CP30 so that element tips are at least 12” from any conductive material (mast, tower, feedline, etc.).
14. Recommended feedlines, in order of preference: Andrews or Celwave 1/2” hardline Times FM-8 or Belden 8214
Try to keep the cable run to under 100 ft. to prevent excessive signal loss.
15. To maintain proper phasing when stacking two or more antennas, mount each with the same orientation of Driven Element
Blocks. DO NOT MOUNT IN MIRROR IMAGE. See the Specification Sheet for stacking distances. For more detailed
stacking information contact M2.
CAREFULLY MANUFACTURED BY:
M2 Antenna Systems, Inc.
4402 N. Selland Ave. Fresno, CA
[phone] FAX [phone]

403CP20 PARTS & HARDWARE
DESCRIPTION QTY
Boom section #1, 1 x .058 x 59" SOE ........................ 1
Boom section #2, 1 x .058 x 19.5" ............................... 1
Boom to mast plate, 3 x 4 x .125" ................................ 1
Elements, 3/16" alum. rod x (see dims.) ..................... 20
Driven element block assembly, ................................ 1
Driven element/ Polarity switch assembly.................... 1
`T' Block assembly ...................................................... 1
Balun, RG-6U halfwave length 13.00” ......................... 2
Phasing line, RG6-U quarterwave length 20.00”......... 1
Phasing line, RG6-U three quarterwave length 7.00” .. 1
U-bolt and cradle, 2” .................................................... 2
U-bolt, 1" no cradle ..................................................... 2
Assembly instructions ................................................. 1
IN HARDWARE BAG
Shorting bars, .75 x 1.532 x .250" mach. alum. .......... 4
Button insulators, 3/16" black ...................................... 40
Shaft Retainers, 3/16" ss ............................................. 40
Nut, 5/16-18 ss ............................................................ 4
Lockwasher, 5/16" ss................................................... 4
Screw, 8-32 x 1-1/4" panhead ..................................... 5
Set screw, 8-32 x 1/4" ss ............................................ 8
Locknut, 8-32 ss .......................................................... 2
Nuts, 1/4-20 ss............................................................. 4
Lockwasher, 1/4-20 ss ................................................ 4
Seal nuts, 3/8-32 gold zinc........................................... 8
Allen wrench, 5/64" ..................................................... 1
Push tube, 3/8 x 3" (for keeper installation) ................. 1
Cable ties, 8"................................................................ 4
M2ANTENNA SYSTEMS, INC.
4402 N. Selland Ave.
Fresno, CA 93722
[phone] Fax: [phone]
www.m2inc.com Email: [email protected]