Tech Library
Antenna Experts Technical Library
Welcome to the Antenna Experts Technical Library, your ultimate resource center for advanced RF and telecommunications engineering data. We understand that in mission-critical communications, precision is everything. Whether you are designing a complex military communication network, upgrading aviation systems, or deploying broadband infrastructure, you need accurate, reliable data. Our technical library is designed to empower engineers, system integrators, and project managers with the comprehensive documentation required to make informed decisions.
Our comprehensive, engineering-focused resource center for radio frequency (RF) design, electromagnetic theory, and specialized antenna technologies. Developed by seasoned RF professionals, this library serves as an authoritative knowledge base tailored for defense procurement officers, aerospace engineers, system integrators, and telecommunications specialists. Whether you are optimizing a mission-critical military communications link or deploying a global commercial network, our curated collection of technical articles, engineering formulas, and application notes provides the foundational insights and advanced data required to streamline your system integration and maximize RF efficiency.
What You Can Find in Our Resource Center
Explore our extensive database of technical documentation, covering our wide range of HF, VHF, UHF, SHF and Microwave antennas. At the core of our Technical Library is a deep dive into the mathematical and physical principles governing electromagnetic radiation. This section offers rigorous breakdowns of fundamental parameters—such as voltage standing wave ratio (VSWR), return loss, radiation patterns, and isotropic gain—translating complex wave equations into practical engineering insights. Visitors can access specialized white papers detailing the distinct mechanics of various antenna architectures, including:
- Log-Periodic and Discone Antennas: Engineered for wideband SIGINT (Signals Intelligence) and Electronic Warfare (EW) applications.
- High-Gain Helical and Quadrifilar Helix Antennas: Designed for precision SATCOM tracking and circular polarization requirements.
- Heavy-Duty Omni-Directional Collinear Arrays: Optimized for rugged TETRA and GSM mission-critical communications.
Each resource is structured to bridge the gap between theoretical RF concepts and real-world deployment challenges. Please visit https://www.antennaexperts.com/design-diagrams for detailed antenna design diagram and https://www.antennaexperts.com/technical-charts for antenna technical charts.
1. Product Datasheets & Specifications
Download highly detailed PDF datasheets for our entire product catalog, including Log Periodic, Horn, Yagi, Dipole, and Omni-directional antennas. Each datasheet includes comprehensive electrical and mechanical specifications, such as:
- Frequency ranges and bandwidths
- Gain, VSWR, and impedance ratings
- Power handling capabilities
- Wind load and environmental survivability limits
2. Radiation Patterns & Engineering Data
Visualizing RF performance is critical to network planning. Access high-resolution Azimuth (H-plane) and Elevation (E-plane) radiation pattern charts to accurately model coverage areas, signal directivity, and front-to-back ratios for your specific project. Some of the radiation patterns are already uploaded in our website. Customer can request radiation pattern files which are not listed in website via email on secure communication compliance.
3. Installation & Maintenance Manuals
Ensure optimal performance and longevity with our step-by-step installation guides. These manuals provide clear instructions on mounting procedures, grounding techniques, weatherproofing connections, and routine maintenance best practices for all Antenna Experts products. Detailed installation and maintenance manual are available in PDF format against each model of antenna in our website.
4. White Papers & Application Notes
Stay ahead of the curve with our in-depth technical articles. Our RF engineering team regularly publishes white papers covering industry trends, antenna design principles, interference mitigation, and application-specific solutions for defense, aerospace, and commercial broadcasting. Beyond core theory, the Antenna Tech Library addresses the practical demands of modern RF system deployment and regulatory compliance. Our extensive catalog of application notes explores critical environmental and mechanical engineering topics, including structural wind-loading calculations, lightning protection strategies, and optimal mast-mounting configurations for harsh, tactical environments.
Why Trust Antenna Experts?
For decades, Antenna Experts has been a global leader in designing and manufacturing premium-grade antenna systems for rugged, high-stakes environments. Our commitment to uncompromising quality means that the data you find in this library reflects the rigorous testing and exacting standards built into every product we ship. Furthermore, we prioritize global trade and engineering standards, offering dedicated documentation on environmental and defense compliance protocols. This includes detailed overviews of RoHS (Restriction of Hazardous Substances), REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals), and strict military-grade environmental testing regimes. By combining deep RF engineering expertise with vital compliance data, our Tech Library stands as an indispensable reference tool for navigating the complexities of modern defense and aerospace RF procurement.
Need a Custom Solution?
If you cannot find the specific data you are looking for, or if your project requires a custom-engineered antenna system, our engineering support team is ready to assist you.
VSWR Vs Return Loss and Effect of VSWR on Transmitted Power
| VSWR | Return Loss (dB) | Transmitted Power (%) |
| 1.0 | ∞ | 100 |
| 1.1 | 26.4 | 99.8 |
| 1.2 | 20.8 | 99.2 |
| 1.3 | 17.7 | 98.3 |
| 1.5 | 14.0 | 96.0 |
| 2.0 | 9.50 | 88.9 |
| 3.0 | 6.00 | 75.0 |
dBm to Watts Reference Table
| dBm | Power (Watts) | Description / Typical Application |
|---|---|---|
| 60 dBm | 1,000 W | High-power Broadcast / Large Radar |
| 53 dBm | 200 W | High-power Tactical Jamming Systems |
| 50 dBm | 100 W | Standard Military Base Station Transmitter |
| 47 dBm | 50 W | Medium-power RF Amplifiers |
| 43 dBm | 20 W | Tactical Manpack Radio (VHF/UHF) |
| 40 dBm | 10 W | Standard Telemetry / Long-range IoT |
| 37 dBm | 5 W | High-power Handheld Radios |
| 33 dBm | 2 W | Common Handheld Radio / SATCOM Uplink |
| 30 dBm | 1 W | 1 Watt Reference Level |
| 27 dBm | 500 mW | Low-power Industrial Transmitters |
| 20 dBm | 100 mW | High-power Wi-Fi / Tactical Mesh Nodes |
| 10 dBm | 10 mW | Short-range Telemetry |
| 0 dBm | 1 mW | 1 Milliwatt Reference (Signal Source) |
| -10 dBm | 0.1 mW | Typical Receiver Input Level |
| -30 dBm | 1.00 uW | Low-level Signal Analysis |
Quick "Rule of Thumb" for Conversions
In the field, you can use the Rule of 3s and 10s for rapid estimation:
- +3 dB = Double the Power (x2)
- -3 dB = Half the Power (/2)
- +10 dB = 10 Times the Power (x2)
- -10 dB = 1/10th of the Power (/10)
Example: If your antenna gain is increased by 3 dB, you are effectively doubling your Effective Radiated Power (ERP).
Antenna Isolation is critical to prevent receiver desensitization and interference, especially in military and defense installations where multiple high-power transmitters operate in close proximity.
Typical Vertical Antenna Isolation Requirements by Frequency
The following table outlines the approximate physical separation required to achieve 30 dB and 50 dB of isolation for vertical antennas (center-to-center).
| Frequency Band | Frequency (MHz) | 30 dB Isolation (h) | 50 dB Isolation (h) | Typical Application |
|---|---|---|---|---|
| HF | 30 MHz | ~11.5 meters | ~36.0 meters | Tactical HF Whip |
| VHF (Low) | 88 MHz | ~4.0 meters | ~12.5 meters | FM Broadcast / Public Safety |
| VHF (High) | 150 MHz | ~2.3 meters | ~7.2 meters | Marine / ATC / LMR |
| UHF | 450 MHz | ~0.8 meters | ~2.4 meters | TETRA / SCADA / UHF Link |
| L-Band | 1200 MHz | ~0.3 meters | ~1.0 meters | GNSS / SATCOM / Radar |
| S-Band | 2400 MHz | ~0.15 meters | ~0.5 meters | 5G / ISM / S-Band Telemetry |
Key Factors Influencing Isolation
- Vertical vs. Horizontal Separation: Vertical separation (stacking antennas on top of each other) provides significantly higher isolation than horizontal separation at the same distance due to the "nulls" in the vertical radiation pattern.
- Polarization: Cross-polarization (e.g., one Vertical and one Horizontal antenna) can add an additional 15–20 dB of isolation.
- Antenna Gain: High-gain directional antennas (like Yagis) pointed away from each other significantly increase isolation compared to omnidirectional antennas.
- Near-Field Effects: At very close distances (less than 2 wavelengths), standard path loss formulas may not be accurate, and empirical testing with a VNA (Vector Network Analyzer) is required.
Typical Horizontal Antenna Isolation (dB) vs. Distance
This table provides the isolation achieved (in dB) at specific horizontal distances (R) for common frequency bands.
| Frequency Band | 1 Meter (r) | 3 Meters (r) | 5 Meters (r) | 10 Meters (r) | Application Context |
|---|---|---|---|---|---|
| VHF (150 MHz) | ~16 dB | ~25 dB | ~30 dB | ~36 dB | Marine / LMR / ATC |
| UHF (450 MHz) | ~25 dB | ~35 dB | ~40 dB | ~46 dB | TETRA / Public Safety |
| GSM (900 MHz) | ~32 dB | ~42 dB | ~46 dB | ~52 dB | Cellular / SCADA |
| L-Band (1.5 GHz) | ~36 dB | ~46 dB | ~50 dB | ~56 dB | SATCOM / GNSS |
| S-Band (2.4 GHz) | ~40 dB | ~50 dB | ~54 dB | ~60 dB | Wi-Fi / ISM / Telemetry |
| C-Band (5.8 GHz) | ~48 dB | ~58 dB | ~62 dB |
Practical Design Considerations
- The "Rule of 6 dB": Doubling the horizontal distance between two antennas typically increases the isolation by approximately 6 dB.
- Pattern Nulls: If using directional antennas, rotating them so they are "back-to-back" can increase isolation by the Front-to-Back (F/B) ratio of the antennas (often adding 15–25 dB of isolation).
- Shielding: Placing a physical metallic barrier or the tower structure itself between two antennas can provide a "shadowing" effect, significantly increasing horizontal isolation.
Basic Knowledge of Antenna
An antenna is a device to transmit and/or receive electromagnetic waves. Electromagnetic waves are often referred to as radio waves. Most antennas are resonant devices, which operate efficiently over a relatively narrow frequency band. An antenna must be tuned (matched) to the same frequency band as the radio system to which it is connected otherwise reception and/or transmission will be impaired.
Wavelength
We often refer to antenna size relative to wavelength. For example: a 1/2 wave dipole is approximately half a wavelength long. Wavelength is the distance a radio wave travels during one cycle. The formula for wavelength is λ = c / f where λ is the wavelength expressed in units of length, typically meters, feet or inches.
Note: The physical length of a half-wave dipole is slightly less than a half-wavelength due to end effect. The speed of propagation in coaxial cable is slower than in air, so the wavelength in the cable is shorter. The velocity of propagation of electromagnetic waves in coax is usually given as a percentage of free space velocity, and is different for different types of coax.
Impedance Matching
For efficient transfer of energy, the impedance of the radio, the antenna and the transmission line connecting the radio to the antenna must be the same. Radios typically are designed for 50 Ohms impedance, and the coaxial cables (transmission lines) used with them also have a 50 Ohm impedance. Efficient antenna configurations often have an impedance other than 50 Ohms. Some sort of impedance matching circuit is then required to transform the antenna impedance to 50 Ohms. Antennas manufactured by Antenna experts come with the necessary impedance matching circuitry as part of the antenna. We use low loss-components in our matching circuits to provide the maximum transfer of energy between the transmission line and the antenna.
VSWR and Reflected Power
Voltage Standing Wave Ratio (VSWR) is an indication of the quality of the impedance match. VSWR is often abbreviated as SWR. A high VSWR is an indication the signal is reflected prior to being radiated by the antenna. VSWR and reflected power are different ways of measuring and expressing the same thing.
A VSWR of 2.0:1 or less is often considered acceptable. Most commercial antennas, however, are specified to be 1.5:1 or less over some bandwidth. Based on a 100 watt radio, a 1.5:1 VSWR equates to a forward power of 96 watts and a reflected power of 4 watts, or the reflected power is 4.2% of the forward power.
Bandwidth
Bandwidth can be defined in terms of radiation patterns or VSWR/reflected power. The definition used is based on VSWR. Bandwidth is often expressed in terms of percent bandwidth, because the percent bandwidth is constant relative to frequency. If bandwidth is expressed in absolute units of frequency, for example MHz.
Decibels
Decibels (dB) are the accepted method of describing a gain or loss relationship in a communication system. The beauty of dB is they may be added and subtracted. A decibel relationship (for power) is calculated using the following formula dB = 10log(Pa/Pb).
Pa might be the power applied to the connector on an antenna, the input terminal of an amplifier or one end of a transmission line. Pb might be the power arriving at the opposite end of the transmission line, the amplifier output or the peak power in the main lobe of radiated energy from an antenna. If Pa is larger than Pb the result will be a positive number or gain. If Pa is smaller than Pb the result will be a negative number or loss.
Directivity and Gain
Directivity is the ability of an antenna to focus energy in a particular direction when transmitting or to receive energy better from a particular direction when receiving. There is a relationship between gain and directivity. We see the phenomena of increased directivity when comparing a light bulb to a spotlight. A 100-watt spotlight will provide more light in a particular direction than a 100-watt light bulb and less light in other directions. We could say the spotlight has more “directivity” than the light bulb. The spotlight is comparable to an antenna with increased directivity.
Gain is the practical value of the directivity. The relation between gain and directivity includes a new parameter η which describes the efficiency of the antenna as G = η x D.
For example, an antenna with 3dB of directivity and 50% of efficiency will have a gain of 0 dB.
Gain Measurement
One method of measuring gain is to compare the antenna under test against a known standard antenna. This is known as a gain transfer technique. At lower frequencies, it is convenient to use a 1/2-wave dipole as the standard. At higher frequencies, it is common to use a calibrated gain horn as a gain standard with gain typically expressed in dBi.
Another method for measuring gain is the 3-antenna method. Transmitted and received powers at the antenna terminal are measured between three arbitrary antennas at a known fixed distance. The Friis transmission formula is used to develop three equations and three unknowns. The equations are solved to find the gain expressed in dBi of all three antennas.
Radiation Patterns
Radiation or antenna pattern describes the relative strength of the radiated field in various directions from the antenna at a constant distance. The radiation pattern is a “reception pattern” as well, since it also describes the receiving properties of the antenna. The radiation pattern is three-dimensional, but it is difficult to display the three-dimensional radiation pattern in a meaningful manner. It is also time-consuming to measure a three-dimensional radiation pattern. Often radiation patterns measured are a slice of the three-dimensional pattern, resulting in a two-dimensional radiation pattern, which can be displayed easily on a screen or piece of paper. These pattern measurements are presented in either a rectangular or a polar format.
Beamwidth
Beamwidth describes the angular aperture where the most important part of the power is radiated. In general, we talk about the 3db beamwidth which represents the aperture (in degrees) where more than 90% of the energy is radiated.
For example, for a 0 dB gain antenna, 3 db beamwidth is the area where the gain is higher than -3 dB.
Near-Field and Far-Field Patterns
The radiation pattern in the region close to the antenna is not exactly the same as the pattern at large distances. The term “near-field” refers to the field pattern existing close to the antenna; the term “far-field” refers to the field pattern at large distances. The far-field is also called the radiation field, and is what is most commonly of interest. The near-field is called the induction field (although it also has a radiation component).
Ordinarily, it is the radiated power that is of interest so antenna patterns are usually measured in the far-field region. For pattern measurement it is important to choose a distance sufficiently large to be in the far-field, well out of the near-field. The minimum permissible distance depends on the dimensions of the antenna in relation to the wavelength. The accepted formula for this distance is rmin = 2D2 / λ where rmin is the minimum distance from the antenna; D is the largest dimension of the antenna; and λ is the wavelength.
Antenna Polarization
Polarization is defined as the orientation of the electric field of an electromagnetic wave. Two often-used special cases of elliptical polarization are linear polarization and circular polarization. The antenna launching the waves into space determines initial polarization of a radio wave. The environment through which the radio wave passes on its way from the transmit antenna to the receiving antenna may cause a change in polarization.
With linear polarization the electric field vector stays in the same plane. In circular polarization the electric field vector appears to be rotating with circular motion about the direction of propagation, making one full turn for each RF cycle. The rotation may be right-hand or left-hand.
