Clackamas Amateur Radio Emergency Services CARES - PowerPoint PPT Presentation

1 / 37
About This Presentation
Title:

Clackamas Amateur Radio Emergency Services CARES

Description:

... repeater coverage, and all situations where repeater-based systems have failed or might fail. ... NVIS requires no infrastructure such as repeaters or satellites. ... – PowerPoint PPT presentation

Number of Views:52
Avg rating:3.0/5.0
Slides: 38
Provided by: clackam
Category:

less

Transcript and Presenter's Notes

Title: Clackamas Amateur Radio Emergency Services CARES


1
  • Presented by
  • Clackamas Amateur Radio Emergency Services (CARES)

2
NVIS
  • Near Vertical Incident Skywave

3
Introduction
  • In this class the basic techniques in the
    theory, use, and making of a NVIS antenna will be
    presented
  • Instructor
  • David Kidd, KA7OZO
  • Emergency Coordinator (ARES)
  • Clackamas Co, Oregon

4
Training Points
  • What is NVIS?
  • How will it work for us?
  • How hard is it to use?
  • Why should I use it?
  • What does it really do for us?
  • What materials are needed?

5
What is NVIS
  • NVIS is a combination of radio hardware, sky wave
    radio propagation, operating procedures,
    cooperation, and knowledge used by a group of
    radio operators who need reliable regional
    communications.
  • NVIS fills the gap between line-of-sight ground
    wave and long-distance "skip" sky wave
    communications.

6
What is NVIS
  • German ground forces first documented NVIS
    techniques in WW-II
  • NVIS was more fully documented, studied, and used
    by US forces in Vietnam
  • NVIS is still used by todays military in combat
    operations

7
What is NVIS
  • NVIS propagation is generally considered to be
    F-layer ionospheric reflection at angles of 70-90
    degrees

8
How will it work for us?
  • Emergency groups such as ARES and RACES are
    studying NVIS propagation, techniques, and
    equipment deployment for emergency preparedness.
  • NVIS is the tactical communication system of
    choice in mountainous areas, any areas without
    complete repeater coverage, and all situations
    where repeater-based systems have failed or might
    fail.

9
How will it work for us? (Cont)
  • With the recent release of manufactured mobile
    and even portable HF radios, HF, and antennas
    employing NVIS propagation, it should become much
    more popular and useful for disaster tactical
    communications.

10
What can NVIS do?
  • This is a mode of HF radio equipment deployment
    that allows for reliable communications within a
    range of 0-400 miles, and depending on condition
    even farther out.
  • NVIS can be viewed more as a "Systems Concept"
    and not just what antenna to use.
  • The concept of NVIS is to have reliable
    communications anywhere within an 800 mile
    diameter circle. Your station would be located
    at the center of this circle.

11
How hard is it to use?
  • NVIS is not just an antenna type or a propagation
    mode -- it is a tactical communications system
    that was designed by military radio operators in
    the field.
  • The NVIS antenna is only part of that system. The
    other part is the knowledge and cooperation of
    the operators, which must be accurately applied
    to achieve the best results -- particularly when
    used in life-and-death situations.
  • Training and coordination is a key factor in
    making it all work properly.

12
How hard is it to use?(Cont)
  • Emergency communications should be driven by
    clearly written procedures that have been
    well-designed and tested.
  • The procedures should be drilled on a regular
    schedule. The drills should be followed by
    debriefings attended by everyone, so that all can
    learn to avoid future mistakes.
  • Suitable procedures are available in books, Field
    Manuals, and on the web. Look for ARES and RACES
    web sites and capture their procedural documents.
    Other excellent sources are FEMA and MARS sites.

13
Why should I use it?
  • To talk close in under 200 miles
  • To have good overall state coverage
  • To have multiple frequency capabilities
  • To have a system that will work under poor band
    conditions

14
Main Reason To Use It
  • First and foremost, to completely eliminate the
    skip zone. This enhances all forms of local and
    regional HF communications, for all practical and
    experimental purposes.
  • Most of all it can be used effectively for
    emergency operations within a local geographic
    area.

15
Among the many advantages of NVIS
  • NVIS covers the area which is normally in the
    skip zone, that is, the area normally too far
    away to receive ground-wave signals, but not yet
    far enough away to receive sky-waves reflected
    from the ionosphere.
  • NVIS requires no infrastructure such as repeaters
    or satellites. Two stations employing NVIS
    techniques can establish reliable communications
    without the support of any third party.
  • Pure NVIS propagation is relatively free from
    fading.

16
More Advantages
  • Antennas optimized for NVIS are usually low.
    Simple dipoles work very well. A good NVIS
    antenna can be erected easily, in a short amount
    of time, by a small team (or just one person).
  • Low areas and valleys are no problem for NVIS
    propagation.
  • The path to and from the ionosphere is short and
    direct, resulting in lower path losses due to
    factors such as absorption by the D layer.

17
Still More Advantages
  • NVIS techniques can dramatically reduce noise and
    interference, resulting in an improved
    signal/noise ratio.
  • With its improved signal/noise ratio and low path
    loss, NVIS works well with low power.

18
(No Transcript)
19
Disadvantages of NVIS operation
  • For best results, both stations should be
    optimized for NVIS operation.
  • If one station's antenna emphasizes ground-wave
    propagation, while another's emphasizes NVIS
    propagation, the results may be poor.
  • Some stations do have antennas which are good for
    NVIS (such as relatively low dipoles) but many do
    not.

20
A Few More Disadvantages
  • NVIS doesn't work on all HF frequencies.
  • Care must be exercised to pick an appropriate
    frequency.
  • The frequencies which are best for NVIS are those
    where atmospheric noise is a problem, antenna
    lengths are long, and bandwidths are relatively
    small for digital transmissions.
  • Due to differences between daytime and nighttime
    propagation, a minimum of two different
    frequencies must be used to ensure reliable
    around-the-clock communications.

21
What materials are needed?
  • Materials are dependent on which antenna type you
    want to use
  • Dipole fixed or portable position
  • Ham stick rotating dipole
  • Military type 2- band version
  • We will discuss material required for each type
  • All are simple to make and use

22
N6VNGs NVIS Antenna
23
Parts List N6VNGs NVIS
  • 2 ea. 1.5" PVC pipes 7.5' long
  • 1 ea. 1.5" PVC coupling
  • 1 ea. 1.5" PVC cap
  • 4 ea. Egg type insulators
  • 5 ea. Brass Screws, nuts and washers to fit
    coaxial fitting
  • 1 ea. SO-239 or UG-266 female panel-mount
    connector with solder pot center pin
  • 5 ea. Stakes (One at the mast center)
  • 4 ea. Heavy solder lugs to fit brass screws
  • 150' Antenna wire
  • 60' Nylon rope
  • Coax to rig. As much as you need. Run it up the
    center of the PVC pipe mast and connect to the
    panel-mount

24
Construction Notes N6VNGs NVIS
  • Drill PVC cap to accept SO-239 and 4 screws and
    nuts
  • Mount SO-239 to PVC Cap with screw heads down
  • Cut off the head of a brass screw
  • Solder a brass screw to center post of SO-239
  • Cut antenna wires to length plus a little
  • Fit one end of each wire with solder lugs
  • Fit the other with the egg insulators
  • Install wires to SO-239 using brass nuts and
    washers
  • as shown in the figure
  • Erect antenna (2 men 5 minutes)
  • Tune antenna match for minimum VSWR
  • (also could adjust mast height and wire lengths)

25
Dual "Ham Stick" version
  • Configuration that shows promise for ARES/RACES
    is to take two mono-band mobile antennas and
    mount them base to base, with one being the
    driven. element and the other being the ground
    side.
  • Care must be exercised in tuning this
    configuration that the elements are the same
    length.
  • They are light weight, portable, fairly
    inexpensive, and easy to put up.

26
Dual "Ham Stick" version
  • This antenna is available at HRO.
  • Antennas are Ironhorse IHF80's and IHF40's (two
    each) and the Ironhorse IH-DAK-AD adapter
  • Total cost for four antennas and the mounting
    bracket is 123.75 (as of 2/21/06).
  • You can use a Radio Shack tripod and five foot
    mast sections for simplicity or 4 sections of
    cammo poles.
  • Plus a run of coax

27
40m Rotating Dipole
  • KC7TOFs rotating 40m dipole and masting
    configuration
  • Very easy to set up and get on the air

28
Frequency Possibilities Modes
  • 40 meters during the day
  • 80 meters at night
  • 160 meters at night if 80m is out
  • The new 60m band with its power antenna
    limitations can be very effective using NVIS
    techniques.
  • Desired modes SSB, RTTY and PACTOR

29
Multi-Band NVIS
  • 40m, 80m, 160m
  • 170 14 stranded wire _at_ 30 with a tuner
  • Budwig Hye-Que type connector - 7.95 _at_ HRO
  • Insulators - one pair _at_ 1.95
  • UV resistant rope for support as needed for
    antenna site

30
Real Life NVIS Use
  • Fixed dipoles at appropriate height
  • Rotating portable dipoles using Ham Sticks
  • Military styled X version with 2 band
    capability - portable/fixed position

31
In Reality . . .
  • Groups of operators using NVIS must understand
    and cooperate on the basics.
  • All must be using NVIS antennas (defined as any
    horizontal antenna well under a quarter-wave
    high), as well as the radio hardware and
    propagation theory.
  • All must understand that the frequencies used
    must stay between the total absorption and
    vertical MUF ranges.
  • The group must decide whether it will equip
    itself to use 160.
  • Calling frequencies and other procedures should
    be established, in writing, with contingencies
    clearly stated.

32
Actual Field Operation Test
  • SET - 9/25/04
  • In parking lot adjacent to new county office
    building on Kaen Rd.
  • KC7CJOs military version antenna on loan to
    CARES
  • Worked great!

33
What This Means
  • NVIS works
  • It is simple to make and simple to use
  • NVIS will fill the gaps during poor propagation
    and conditions
  • Minimum NVIS capability will cover the entire
    state of Oregon
  • NVIS can reach the capitals of the adjoining
    states of CA, NV, WA, ID from our county

34
Next Steps
  • Since you now know the basics of NVIS, it is time
    to put your knowledge to use
  • You can make one, buy one, or borrow one . . .
    Just try it and I know you will become a believer

35
Links to NVIS URLs
  • www.qsl.net/wb5ude/nvis/
  • www.athensarc.org/nvis.htm
  • www.w0ipl.com/ECom/NVIS/nvis.htm
  • www.co.missoula.mt.us/acs/ACS/NVISpage1.htm
  • www.co.missoula.mt.us/acs/ACS/N6VNG20AS2259.htm

36
Presentation Credits
  • Whats the deal about NVIS? By Dean Straw,
    N6BV, QST Dec 2005
  • NVIS Operations by Ed Farmer, AA6ZM, QST, Jan
    1995
  • The NVIS - A Low Antenna for Regional
    Communications by Albert Pion, KK7XO, QST, Jun
    2002
  • NVIS by Norm Fusaro, W3IC, internet PPP
  • Understanding NVIS Antennas Propagation by
    Harold Melton, KV5R, 2002, 2006

37
Just about the end
  • Questions ?
  • Thank you showing interest in NVIS antennas!
  • I look forward to helping you get started with
    your NVIS antenna project
Write a Comment
User Comments (0)
About PowerShow.com