Have you ever tried to get through the concept of metal detector frequency? When I took up this hobby, I tried to do some research. But I didn’t succeed and bought a metal detector that seemed good because of its price. After some time passed, I understood that such an approach doesn’t work. You should understand the operating principles, advantages, and disadvantages of this or that technology and use them to the maximum.
Contents
- 1 What is the frequency?
- 2 What does metal detector frequency affect?
- 3 High frequency metal detectors
- 4 Low frequency metal detectors
- 5 Best frequency for gold detectors
- 6 Single-frequency, multiple-frequency or multi-frequency metal detector
- 7 Choosing Between Multiple-Frequency and Single-Frequency Metal Detectors
- 8 Conclusions
- 9 Metal Detector Frequency Chart
What is the frequency?
In physics, frequency refers to the number of occurrences of a repeating event per unit of time and is typically measured in kilohertz (kHz). In the context of metal detectors, frequency plays a crucial role in how the device functions.
The operating principle of metal detectors—whether they use Very Low Frequency (VLF), Pulse Induction (PI), or Radio Frequency (RF) technologies—remains fundamentally the same. These devices rely on electromagnetism to detect objects. A metal detector emits an electromagnetic wave and quickly receives signals of disturbance when the emitted wave encounters an obstacle. These disturbances occur when the wave interacts with objects that have different electrical conductivities, which alters the wave’s behavior.
Objects with high electrical conductivity produce different disturbance patterns compared to those with low conductivity. This difference allows the metal detector to distinguish between various types of materials. Discrimination, the process of filtering out certain disturbances, enables the detector to ignore unwanted signals and focus on more relevant targets.
When it comes to metal detecting, frequency refers to the number of electromagnetic waves emitted per second by the search coil into the ground. For instance, a detector operating at 10 kHz emits and receives 10,000 waves per second. The frequency range for most metal detectors typically falls between 3 kHz and 100 kHz, with each frequency offering different capabilities.
Each metal detector frequency is better suited for certain tasks. Higher frequencies are more sensitive to smaller objects, while lower frequencies penetrate deeper into the ground, making them ideal for detecting larger, deeper targets. As a result, a specific frequency can behave differently depending on the environment and the nature of the target. Understanding how frequency affects detection depth and object size is key to choosing the right settings for metal detecting.
Now that we’ve clarified the basics, let’s explore how this knowledge can improve your metal detecting experience.
What does metal detector frequency affect?
Let’s focus on VLF metal detectors, the most popular type among hobbyists. These detectors are commonly categorized based on their operating frequency:
- Low frequency: Up to 8 kHz
- Medium frequency: 8-20 kHz
- High frequency: Above 20 kHz
It’s important to note that these divisions are somewhat flexible. The classification of frequencies can vary between sources, and there is no universally accepted frequency standard. For example, while beginner metal detectors once typically operated at 6-8 kHz, a range considered medium frequency, newer models now often feature operating frequencies of 12-15 kHz. This shift is largely due to competition and advances in the market.
Most entry-level metal detectors still operate within the medium frequency range, generally between 6-8 kHz. Popular models include the Teknetics Eurotek, Garrett Ace 250, Minelab Go-Find, Bounty Hunter Land Ranger Pro, Bounty Hunter TK4 Tracker IV, and White’s Coinmaster, to name a few. These detectors strike an optimal balance between sensitivity and detection depth, making them versatile for a variety of uses.
Operating within this metal detector frequency range provides the benefits of both low and high frequencies. For example, these detectors offer sufficient depth for larger targets while maintaining good sensitivity for smaller objects. Additionally, they tend to be less noisy when used in highly mineralized soils or rocky areas, often referred to as “hot rocks.”
Many of these devices don’t require advanced ground balancing, which simplifies their use. Detectors operating below 10 kHz are especially well-suited for coin shooting, as their frequency is ideal for detecting metal objects like coins while minimizing interference from the ground.
High frequency metal detectors
The operating frequency of a metal detector directly influences its performance, particularly in terms of target detection and sensitivity to electromagnetic interference.
Higher operating frequencies (above 10 kHz) are better suited for detecting small targets like gold nuggets and other low-conductivity metals, such as iron and nickel. These frequencies also tend to be less affected by electromagnetic noise from sources like power lines or mobile phones, making them ideal for areas with high electrical interference. However, higher frequencies come with trade-offs, particularly in detection depth. As the frequency increases, the detector becomes less capable of penetrating deep into the ground and struggles with mineralized soils. The sensitivity to small, near-surface targets improves, but detection depth for larger targets decreases.
Some key characteristics of high-frequency detectors include:
- Shorter wavelength, which enhances their ability to detect small objects close to the surface.
- Ideal for detecting low-conductivity metals like gold or iron.
- Reduced detection depth compared to low-frequency detectors.
- Greater precision when scanning for targets close to the ground.
- Higher susceptibility to mineralized soils, which can lead to more noise and less stable readings.
High-Frequency Metal Detectors
- Minelab CTX 3030
- Frequency Range: 1.5 kHz – 100 kHz
- Features: Advanced multi-frequency technology, GPS, and waterproof.
- Minelab Equinox 800
- Frequency Range: 5 kHz, 10 kHz, 15 kHz, 20 kHz, and 40 kHz
- Features: Multi-IQ technology for simultaneous frequency operation, lightweight, and waterproof.
- XP DEUS II
- Frequency Range: 4 kHz to 45 kHz (adjustable)
- Features: Wireless operation, customizable settings, and lightweight design.
- Nokta Makro Simplex
- Frequency Range: 15 kHz
- Features: Affordable, waterproof, and equipped with advanced features for beginners.
- Fisher F75
- Frequency Range: 13 kHz
- Features: Lightweight, fast recovery speed, and multiple modes for various conditions.
- Garrett AT Max
- Frequency Range: 13.6 kHz
- Features: All-terrain capability, wireless audio, and enhanced depth detection.
- Minelab Vanquish 440
- Frequency Range: Multi-frequency (adjustable)
- Features: User-friendly, quick response time, and lightweight.
- Teknetics T2 Classic
- Frequency Range: 13 kHz
- Features: High sensitivity, fast recovery, and a user-friendly interface.
Low frequency metal detectors
In contrast, low-frequency metal detectors (below 8 kHz) offer better detection depth, making them ideal for larger, deeper targets. These frequencies excel at detecting high-conductivity metals such as silver and copper but are less effective at identifying small objects like gold. Because of their longer wavelength, low-frequency detectors penetrate deeper into the ground, making them suitable for tasks like deep search metal detecting. However, they are less sensitive to small targets near the surface and to metals with lower conductivity, such as gold.
Key characteristics of low-frequency detectors include:
- Longer wavelength, allowing for deeper ground penetration.
- Better suited for high-conductivity targets like silver and copper.
- Lower sensitivity to small or near-surface targets.
- Less effective for low-conductivity metals, such as gold.
These trade-offs make it essential to choose a metal detector frequency range that matches your specific detecting needs, whether you prioritize depth, target size, or conductivity.
Low-Frequency Metal Detectors
- Garrett ATX
- Frequency Range: 2.5 kHz – 5 kHz (adjustable)
- Features: Military-grade, all-terrain capability, and advanced pulse induction technology for deep searching.
- Whites TM 808
- Frequency Range: 6.59 kHz
- Features: Designed for deep searching, suitable for locating large metal objects and underground caches.
- Minelab Explorer XTerra 705
- Frequency Range: 3 kHz, 7.5 kHz, 18.75 kHz (switchable)
- Features: Versatile with multiple frequency options, suitable for various targets and conditions.
- Bounty Hunter Land Ranger Pro
- Frequency Range: 7.69 kHz
- Features: Beginner-friendly, equipped with digital target ID, and suitable for various terrains.
- Garrett ACE 250
- Frequency Range: 6.5 kHz
- Features: Beginner-friendly, lightweight, and a good choice for coin shooting and jewelry detection.
Best frequency for gold detectors
If your goal is gold prospecting, most metal detectors designed for this purpose operate at a high frequency. This is due to two main factors: gold’s low conductivity and the fact that gold nuggets often consist of small particles. Higher frequencies are much more effective at detecting low-conductivity metals and small-sized targets.
The minimum metal detector frequency generally recommended for detecting gold nuggets is 14 kHz. Frequencies lower than this greatly reduce the detector’s ability to pick up small gold pieces. Detectors with a frequency below 14 kHz may struggle to identify smaller targets, especially in areas where gold is fine or mixed with other minerals. Thus, choosing a detector with a higher operating frequency significantly increases your chances of success in gold prospecting.
Single-frequency, multiple-frequency or multi-frequency metal detector
Most metal detectors operate on a single frequency, which is typical for beginner models. These devices do not allow users to switch between different frequencies or use multiple frequencies simultaneously. However, more advanced options are available on the market, known as multi-frequency metal detectors, which offer a range of advantages.
There are two main types of multi-frequency metal detectors. The first type allows users to select from several frequencies but can only use one at a time. These detectors are equipped with multiple frequencies, enabling users to switch between them as needed. For example, after scanning an area at one frequency, you can switch to another and continue searching. Some models change their frequency when replacing the search coil, but most modern devices come with coils that can operate on multiple frequencies simultaneously. Popular models in this category include Nokta Impact, XP DEUS, and Minelab Equinox 600.
The second type is true multi-frequency metal detectors, which analyze signals received on two or more frequencies simultaneously. These devices emit a primary frequency, accompanied by secondary harmonic frequencies. For instance, if the base frequency is 15 kHz, the harmonic frequencies might be 30 kHz, 45 kHz, and 60 kHz, which are multiples of the base frequency. This capability allows the detector to assess the ground at various frequencies in a single pass, significantly increasing the likelihood of detecting different types of metal objects.
While there are only a few true multi-frequency models on the market, such as the Minelab CTX 3030, Minelab Vanquish, and Minelab Equinox 800, these devices are highly valued for their accuracy and versatility. The Minelab Multi-IQ technology, which is patented by the company, allows for the simultaneous use of multiple frequencies ranging from 5 kHz to 40 kHz, providing flexibility in various conditions. This is one reason Minelab dominates this category, and their devices remain the preferred choice for experienced treasure hunters.
Experienced treasure hunters often recommend first surveying promising areas with a high-frequency metal detector to locate small or low-conductivity targets, such as gold. Then, a low-frequency detector can be used to search for larger or deeper targets. However, with a multi-frequency detector, this process becomes much more efficient. Such devices can simultaneously analyze the ground using low, medium, and high frequencies, allowing detectorists to save time while achieving higher efficiency.
Choosing Between Multiple-Frequency and Single-Frequency Metal Detectors
Choosing between a multiple-frequency and a single-frequency metal detector largely depends on your specific treasure-hunting goals and the types of targets you aim to find.
Operating Metal Detector Frequency Considerations
If you’re primarily searching for small items such as coins, earrings, and other non-ferrous targets, opting for a high-frequency metal detector is advisable. High frequencies (typically above 20 kHz) excel at detecting small targets, as they are more sensitive to low-conductivity metals like gold.
For larger targets, such as coins, bullet casings, and buckles, a medium-frequency detector (generally between 8 kHz and 20 kHz) would be more suitable. This metal detector frequency range provides a balanced sensitivity and depth, making it effective for a variety of metal types.
If your goal is to find deep, hidden treasures like hoards, helmets, or other large items buried in the ground, you should consider a low-frequency metal detector (up to 8 kHz). Low frequencies penetrate the ground better, allowing for deeper detection but may be less sensitive to smaller targets.
Seasoned Approach to Selection
A common strategy for beginners is to start with a metal detector that has a medium operating frequency during the first season. This approach helps you familiarize yourself with the device, understand the potential of the specific areas where you are detecting, and learn about the types of finds you can expect. Most beginner metal detectors operate within this frequency range, making them accessible and versatile for various target types.
Given that some areas can be quite trashy with lots of metal debris, many beginner-level detectors come equipped with a mono-coil (often concentric), which is designed for multi-purpose use and provides a balanced search experience. This type of coil helps filter out unwanted signals, making it easier to identify valuable targets.
As you enter your second season of metal detecting, you’ll have a clearer understanding of your preferences and the specific conditions of the areas you frequent. At this stage, you can make more informed decisions regarding coil size and frequency based on your past experiences. You will also gain insights into the benefits of small versus large search coils, as well as which frequencies yield the best results for specific targets.
Conclusions
It is more efficient to use metal detectors with several frequencies or multi-frequency ones. Moreover, nowadays, the multi-frequency feature has become available even for simpler device models (see Minelab Vanquish). If you can’t afford getting such a device, get a single-frequency metal detector. Don’t worry, you’ll find your treasures anyway, you won’t miss anything.
Metal Detector Frequency Chart
| Brand | Model | Frequency Type | Frequency |
|---|---|---|---|
| Bounty Hunter | Discovery 1100 | VLF | 6.6 kHz |
| Bounty Hunter | Gold Digger | VLF | 6.6 kHz |
| Bounty Hunter | Land Ranger Pro | VLF | 7.69 kHz |
| Bounty Hunter | Discovery 3300 | VLF | 6.6 kHz |
| Fisher | F22 | VLF | 7.69 kHz |
| Fisher | F44 | VLF | 7.69 kHz |
| Fisher | F75 | VLF | 13 kHz |
| Fisher | CZ-21 | VLF | 5 KHz and 15 KHz |
| Brand | Model | Frequency Type | Frequency |
|---|---|---|---|
| Garrett | ACE 150 | VLF | 6.5 kHz |
| Garrett | ACE 250 | VLF | 6.5 kHz |
| Garrett | ACE 300 | VLF | 8 kHz |
| Garrett | ACE 350 | VLF | 8 kHz |
| Garrett | ACE 400 | VLF | 10 kHz |
| Garrett | ACE Apex | Multi-Frequency | 5, 10, 15 and 20 kHz |
| Garrett | AT Pro | Multi-Frequency | 15 kHz |
| Garrett | AT Gold | VLF | 18 kHz |
| Garrett | ATX | Pulse Induction | Variable |
| Garrett | Sea Hunter Mark II | Pulse Induction | Variable |
| Garrett | GTI 2500 | VLF | 7.2 kHz |
| Brand | Model | Frequency Type | Frequency |
|---|---|---|---|
| Minelab | Equinox 800 | Multi-Frequency | 5 kHz – 40 kHz |
| Minelab | CTX 3030 | Multi-Frequency | 1.5 kHz – 100 kHz |
| Minelab | GPX 5000 | Pulse Induction | Variable |
| Minelab | Excalibur II | Multi-Frequency | Variable |
| Minelab | SDC 2300 | Pulse Induction | Variable |
| Minelab | Gold Monster 1000 | VLF | 45 kHz |