Section 3.4: VHF and UHF Waves #

As a Technician class operator, you’ll spend much of your time on the VHF and UHF bands. These are the heart of local communications and are perfect for getting started in amateur radio. Let’s explore these bands and see why they’re so popular among new hams.

Frequency Ranges #

VHF (Very High Frequency) and UHF (Ultra High Frequency) cover:

• VHF: 30 MHz to 300 MHz
• UHF: 300 MHz to 3 GHz

The most popular Technician class bands are:

• 2 meters (144-148 MHz) - VHF
• 70 centimeters (420-450 MHz) - UHF

Here’s a neat trick: want to know the wavelength of a frequency in meters? Just divide 300 by the frequency in MHz. So for 146 MHz, you get about 2 meters. It’s like a seesaw - as frequency goes up, wavelength goes down. This relationship is super important in antenna design and understanding how radio waves behave.

Key Characteristics #

1. Line-of-Sight Propagation: VHF and UHF waves generally travel in straight lines, similar to light. This makes them reliable for local communications. They are not usually propagated by the ionosphere, so sky wave propagation generally does not apply

2. Compact Antennas: Higher frequencies mean shorter wavelengths, allowing for smaller, more manageable antennas. This is great for portable and mobile operations.

3. Less Affected by Ionospheric Conditions: Unlike HF bands, VHF and UHF are less impacted by solar activity, providing more consistent local communications.

4. Ideal for Repeater Use: Many repeaters operate on these bands, greatly extending the range of your radio.

Practical Applications #

1. Local Communication: Perfect for chatting with nearby hams or participating in local nets.

2. Emergency Communications: Often used by ARES (Amateur Radio Emergency Service) and RACES (Radio Amateur Civil Emergency Service) for disaster response.

3. Public Service Events: Ideal for providing communication support for marathons, parades, and other community events.

4. Satellite Operations: Many amateur satellites use VHF and UHF frequencies.

Getting Started on VHF/UHF #

1. Equipment: Most new hams start with a VHF/UHF handheld transceiver (HT) or a mobile rig.

2. Repeaters: Learn to use local repeaters to extend your range. You’ll need to know about:

   • Repeater offset: The difference between a repeater’s input and output frequencies.
   • PL tones (CTCSS): Subaudible tones used to access many repeaters.

3. Simplex Operations: Try direct radio-to-radio contacts without using a repeater.

4. Antenna Considerations:

   • Height matters more than power on these bands.
   • Most antennas for FM use are vertically polarized.

5. Modes:

   • FM is most common for voice communications.
   • Packet radio and other digital modes are also popular.

Band Plans #

It’s important to use the right frequencies for different activities:

• 146.52 MHz: National FM simplex calling frequency on 2 meters
• 446.00 MHz: National FM simplex calling frequency on 70 cm

Always check your local band plan, as frequency usage can vary by region.

Tips for Success #

1. Start by listening. Get familiar with local repeaters and nets.
2. Join a local club. They often offer VHF/UHF nets and can help you get started.
3. Participate in public service events to gain experience.
4. Experiment with different antennas to improve your signal.

Looking Ahead #

As you gain experience, you might explore:

• Weak signal work on SSB
• Satellite communications
• Digital modes like FT8 or FT4

Remember, VHF and UHF bands offer a perfect entry point into the world of amateur radio. They provide reliable local communications, opportunities for public service, and a stepping stone to more advanced operations. As a Technician, mastering these bands will give you a solid foundation in amateur radio operations and open doors to many exciting aspects of the hobby.