Developed and Presented By: Martin Dunsmuir, AScT, VE7BDF, VE0MD President, White Squall Consulting Inc. NVIS Antenna System Design, Construction and Deployment Emergency HF Communication Options

2 Many administrations are strongly focused on VHF/UHF communications which is very important for local area first responder communication. If a serious disaster occurs VHF/UHF communication could be compromised, including mountain top repeaters and the internet, leaving HF as the only direct option. HF base station operation could also be degraded or eliminated due to building damage leaving portable operation as the only option for HF communication. Under these conditions, RELIABLE, SECURE and PORTABLE HF communication will be required to maintain contact with EMBC and other Provincial EOC’s. White Squall Consulting Inc. - Emergency HF Communication Options

3 Distance to EOC’s and EMBC stations for required contact during emergencies, Best antenna configuration for reliable HF communication over an extended period, Able to provide reliable communication to Provincial EOC’s outside of ground wave reception. Simple inexpensive antenna construction with ease of deployment. White Squall Consulting Inc. - Emergency HF Communication Requirements

HF Vertical antennas are not suitable due to their low angle of radiation which is excellent for DX but poor for communication within the Province. HF Dipole antennas would work better but they do not offer omni directional signals and their radiation characteristics split the output signal between the horizontal and vertical, An HF NVIS antenna system would provide the best choice for reliable communication within the Province. 4White Squall Consulting Inc. - HF Emergency Antennas

5 HF NVIS Communication Range Most emergency communication during a disaster will occur within the province. Reliable secure communication over a radius of around 350 miles would solve this problem. This can be easily accomplished using an NVIS antenna system. White Squall Consulting Inc. -

6 NVIS antenna systems work best on frequencies below 10 MHz and essentially transmit a high angle (> 70°) signal that will be refracted back to earth from 1 to 350 miles from the transmitter. NVIS antennas are inexpensive, simple to construct and easy to deploy. The NVIS system also works best when it is close to ground level which provides a great advantage for portable operation. NVIS antennas are also much less affected by noise as most noise arrives at the antenna at low angles. White Squall Consulting Inc. - HF NVIS Antenna Advantages

7White Squall Consulting Inc. - HF NVIS Antenna Design NVIS antennas are very simple to construct from inexpensive PVC or ABS plumbing pipe. The drawing to the right shows the layout of the top section of an NVIS antenna. Note that the bottom of this assembly can be adapted to use either 1 ½” or 2” ABS or PVC pipe. All fastenings should be stainless steel with the exception of the radial connectors which are usually copper. Mechanical Assembly

White Squall Consulting Inc HF NVIS Antenna Design Top Section as Built – View 1 1 ½” Pipe End Cap usually not glued to allow for easy access. Insert ¼ λ antenna radials into copper radial connectors. When tightened this connector will securely hold the radials. We also use “Never-Seize” compound to reduce corrosion and improve electrical connection. 1 ½” End Cap inserted in the 2” PVC Pipe to 2” threaded adapter centered and secured using PVC or ABS Glue. 2” to 1 ½” or 2” to 2” threaded pipe to pipe adapters could be used here depending on whether 2” or 1 ½” pipe will be used for the antenna mast.

White Squall Consulting Inc. - HF NVIS Antenna Design Top Section as Built – View 2 Antenna radial connectors ¼” x 1” SS Cap Screws ¼” Nylock SS Nuts

White Squall Consulting Inc HF NVIS Antenna Design Bottom View 2” Pipe to threaded pipe adaptor. 1 ½” pipe end cap installed in 2” pipe to threaded pipe adapter and secured with ABS or PVC glue. UHF Connector mounted in the 1 ½” end cap using 4-40 SS Bolts and washers. 2” threaded pipe to 1 ½” threaded pipe adapter removed for picture.

White Squall Consulting Inc HF NVIS Antenna Design Antenna Base End View 1 ½” or 2” PVC Pipe ¼” PVC Sheet Glued to pipe 0.125” - 1 ½” x 1 ½” Aluminum Angle ¼” x 1” SS Cap Screws + ¼” SS Nylock Nuts Cut to size of coax

White Squall Consulting Inc. - HF NVIS Antenna Design Antenna Base Side View 1 ½” or 2” PVC Pipe ¼” PVC Sheet ¼” x 1” SS Cap Screws + ¼” SS Nylock Nuts

13 HF NVIS Antenna Deployment NVIS HF Portable Antenna Example: Could be roof mounted if space is available. White Squall Consulting Inc. -

14 All of our portable tests were carried out using this antenna configuration, 18” lengths of 3/8” rebar were driven into the ground to provide radials support, Antenna mast was hinged for transport with radials connected, but coiled, After parking, the antenna was deployed in about 30 minutes. HF NVIS Antenna Deployment

White Squall Consulting Inc HF NVIS Antenna Characteristics Our testing has shown that an NVIS antenna constructed with radials for 80 and 40 meters plus the addition of an inexpensive tuner will also operate well on 60 meters. Radials for 160 meters were not added or tested due to lack of space.

White Squall Consulting Inc HF NVIS Equipment Configuration Tests with the equipment configuration shown was used for base station as well as portable tests. Operation on 80 to 40 meters including several commercial frequencies were tested with excellent results. VSWR readings in all cases were < 2.0. NVIS antennas were mounted on the top of buildings for base stations and on a vehicle as shown for portable operation.

White Squall Consulting Inc. - NVIS System History We have constructed and installed several NVIS antenna systems for clients over the years, the oldest installation over 10 years ago. During that time none of those antennas have experienced damage due to wind or other issues. All of the NVIS antenna systems are all still in operation and working well.

18 HF Noise Elimination Equipment BHI Noise Elimination Speaker Uses the latest DSP technology to remove unwanted background noise, hiss,hash, QRM, QRN or thermal noise leaving only the speech. How Does it Work? The DSP circuit processes the received signal and differentiates the noise from the speech. This unwanted noise and interference is then attenuated to leave only the speech. The DSP technology is fully adaptive and no adjustments are necessary. The received signal is constantly monitored and the DSP automatically adapts to any changes in signal conditions. White Squall Consulting Inc. - SSB Voice Operation Tests were also carried out with the NVIS antenna system for voice communication using the BHI Noise Elimination speaker shown. This allowed weak signals to be received during poor S/N conditions

White Squall Consulting Inc. - HF Noise Elimination Equipment Other Capabilities These speakers also have a jack for a headset use. Rotary noise cancellation filter level switch allows the user to select from 1 to 8 different settings with level 1 providing the least amount of noise cancellation and level 8 providing the most. The unit is factory set for level 6.