Genesys Resonant Active Tunable
*****
GRAT – Antenna
*****
February 2012
Introduction
Since 2006 Genesys had been developing an antenna for specific use in RCIED
jamming application. However, the new design of the antenna proved to have
unique features and characteristic to allow vast potential and wide area of
application:
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Line-of-sight communication devices for emergency services (police, ambulance,
firefighters, etc),
Vehicle-born hidden antennas system;
The vehicle and ships intercom wireless network;
Railway transport communication and security;
Ships and boats communication;
Aircraft-type antenna;
Satellites, any types;
Robotic Systems (remote control and data acquisition);
Unmanned devices, Line-of-Sight local control;
Missile delivered radio-beacon, repeater or RF jamming unit
NOTE: Dimension directly depended on used frequency. This presentation is based
on our design for the specific application of antenna. The sizes, dimensions,
weight apply to this particular application and can easily be decreased for use in
hand-held devices with no degradation to the feature set.
Invention
The Genesys LTD introduce new concept in RF antenna
developing.
Working model: Genesys Resonant Active Tunable (GRAT) Antenna
The design concept:
Small-sized,
tunable
wide-band
loop-slot antenna.
The general specifications of
emission and receiving of our
antenna close to classical
quarter-wave antenna.
The functionality of the
antenna:
transmitting/receiving,
wideband tunable, narrow
passband on tuned frequency,
resonant, harmonicsuppressed antenna.
The differences is in a very
narrow passband and the
possibility of fast tuning of the
passband central frequency.
The GRAT-antenna is a basic element and depending of application can
be used as a single antenna or as the set of antennas for the variety of
transmitting and receiving systems.
Invention explanation
The classical theory for the design of antenna systems considers the antenna as an open
oscillatory circuit which is excited by an electrical signal. As the result, the antenna can
either, accept external electromagnetic waves, or antenna circuit should generate an
electrical signal for the emission of electromagnetic waves. For small-sized antennas, the
optimum size is a half the length of the working wavelength.
Meanwhile, there are many other approaches in the design of antennas for implementing
missing features in an open resonant circuit type antennas.
This group of antennas includes phased array antennas, fractal antennas, log periodic
antennas, etc.
In most cases, the linear dimensions of antenna equals to a quarter or half of the working
wavelength, which relates to the basic principle of designing an antenna as an open
oscillatory circuit.
Known improvement of their parameters are mainly related to the possibility of adding
directional selectivity or limiting the range of received frequencies.
The features of the GRAT-antenna design give opportunity to replace whip antennas used
in HF,VHF and UHF diapasons.
Without losing all the positive properties of standard antennas, plus, the GRAT antenna
has a wideband characteristic with a harmonic-suppression characteristic. the proposed
GRAT antenna makes it possible to create an energy-efficient, barely visible, durable,
antenna systems for radio communications task, RF monitoring and using with
contemporary protecting RF devices.
Major advantages: Size
The dimensions of the GRAT-antenna
directly relates to the wavelength of
used bandwidth and can be easy
calculated. The high is equal to the
lower work frequency wavelength (λ)
multiplying by 0.01, and length is equal
to λ*0.1.
Rod/Whip antenna
height -
98.42“
(standard band 30 MHz to 89 MHz)
GRAT-Antenna
GRAT-Antenna height is just slightly more than the OEM roof rack.
The profile of the vehicle almost does not change after installation.
height length
3.19"
31.92“
(calculated for working frequency: 37 MHz)
No long-whip antenna
Benefits and examples of use
GRAT Antenna can successfully
replace the standard antennas
used now: 4-foot long whips.
Solved problem: No need to tie down long-whip antenna.
This is usually done in urban environment to avoid impact
between the long-whip antenna and hanging wires or other
obstacles. When the long-whip antenna tied down or
lowered it looses its workability. GRAT antenna newer
strike electric wires, telephone cables, etc.
GRAT Antenna has very low
vertical profile
Solved problem: GRAT antenna installed on the vehicle and
when used as a part of jamming system allows better
concealment comparing with long-whip antennas.
GRAT Antenna: compact and
rigid
Solved problem: The long-whip antennas often can snip or
break at the impact. In addition to being compact GRAT
antenna can be manufactured to be rigid. This shall
significantly lower necessity to troubleshoot, fix, replace
antennas itself.
GRAT Antenna: Portability
The design of the antenna allows easy portability. Roofmounted design eliminates the need to install whip rods on
vehicle’s bumper where it usually requires cables to be
placed outside of the vehicle, requires special mounting
provisions, gets in the way of doors, and thus makes antenna
more prone to problems.
Major references
1)
2)
Q-factor Q  100; (Our latest experiments with new, next generation, antenna
prototype give as an opportunity to expect quality factor increasing to Q  1000 );
f
f
The bandwidth of the antenna  f  max  0  0.01 f 0 (represents the difference, depending
0
f min Q
on the quality factor, between the upper and lower limit frequencies of the antenna;
3)
Availability of electronic tuning to the specified resonance frequency value ( f 0 ) (by varactor
diodes or switched capacitors etc);
4)
The coefficient of overlap in frequency
K
0

C max
 2...4 (where C represents max and min
C min
value of tuning capacitance),
5)
The height of the antenna curtains h  0.02...0.01max ;
6)
The length of the antenna curtains l  0.2...0.1max ;
7)
Vertical polarization;
8)
Omni-directional pattern (basic models);
9)
Strong electric (E) and magnetic (H) fields increase the reactive near-field to no less than
0.5 which is larger than the near-field of classical antennas, as known as 0.15 ;
Major advantages: Quality
The classical Q-factor, defined as the quotient
between the stored and radiated energies for
our GRAT antenna is Q=100
 Our latest experiments with new, next
generation, antenna prototype give as an
opportunity to expect quality factor increasing
up to 1000
 high performance decrease or eliminate
unwanted and spurious emission
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Major advantages: Bandwidth
The bandwidth of the antenna Δƒ depends on Q-factor and operating
frequency range
 The bandwidth of the our antenna is 1%. The standard quarter-wave
vertical antennas have a bandwidth of 20…200 times larger than our
GRAT antenna.
 The active tuning mode allow overlap frequency range with coefficient K =
2…4
 Allow to design protected, narrowband, multi channel communication
devices with expanded “Frequency Hopping” capability.
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GRAT-Antenna allows to achieve several highly important goals pursued by
the Battlefield Spectrum Management:
It increases the maximum number of frequencies available in the area of
operation and spreads the frequencies in the hopsets across the widest
possible band to optimize Electronic Counter-Counter Measures (ECCM)
capabilities.
Spreading the frequencies across the spectrum is more important than
increasing the total number of frequencies available.
Major advantages: Power
Strong electric (E) and magnetic (H) field
increases the reactive near field to not less
than 0.5λ that is more than the near field
of classical antennas, equal, as is known,
0.15λ
 Control circuit allow reduce power
consumption up to 80% in some
applications
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Major advantages: Other
•Narrow passband antenna with wide range
tuning
•Electronically or manually tuning
•Flat gain over frequency range
•Low vertical dimension of antenna
•Circular radiation pattern (basic), or can be
modified
•Either, fixed frequency or scanning frequency
operation mode
•Improve receiver third-order
intermodulation dynamic range
•Improve receivers signal-noise, post
processing, ratio
•Active, sharp, cancellation of antennas posttransmitting oscillation
•Possibility to create silent/active spot pattern
in active frequency band.
•Can be used as a standalone device
•Can be mounted as a parts of the object of
interest
•Compatibility with SDR communication
devices
•SDR system hardware design simplification
•Good replacement for rod/whip VHF
antennas
•In some cases, eliminates the need for RF
amplifier for the transmitter
•Decrease unwanted oscillation in
transmitting mode
•Increase sensitivity and selectivity of the
receivers
•Increase receivers interference immunity
•EMC improvement
SDR-based Radio systems
The main concept of the Software-Defined Radio (SDR) radio is that the radio can be totally
configured or defined by the software. In this case a common platform can be used across a
number of areas and common software can be used to change the configuration of the radio
for the function required at a given time.
Launched with a Mission Needs Statement in 1997 and a subsequent requirements document in 1998, The Joint
Tactical Radio System (JTRS) is planned to be the next-generation voice-and-data radio used by the US military in field
operations after 2010. The JTRS is a Software-Defined Radio (SDR) that will work with many existing military and
civilian radios.
SDR allows to use single hardware platform and it can communicate using one of a variety of waveforms simply by
reloading or reconfiguring the software for the particular application required. This is a particularly attractive aspect,
especially for coalition style operations where forces from different countries may operate together. The radios can be
re-configured to enable communications to occur between troops from different countries, etc.
One of the basic goals underlying the construction of SDR systems is to maximize simplification
of the structure and/or exclude analog components. Nevertheless, this simplification often
reduces the efficiency of SDR systems. Particularly in conditions when powerful signals exist
outside the band received frequencies. The reason for this is to ignore, in most cases, necessity
to filter the desired signal before the first amplification stage, or signal conversion. However,
adding the filters greatly complicates the technical implementation of the SDR system.
As we proclaimed in a beginning, when the proposed antenna is parts of SDR system , the
antenna play additional role of tunable receiver preselector, and easily controlled by settings
of SDR system itself.
RECEIVING MODE
TRANSMITTING MODE
SDR-based Radio systems
IN RECEIVING MODE
combination of SDR system and the proposed antenna will
improve the following characteristics of the RF system:
Improves the parameters of EMC by increased
noise immunity
Extends the receiver third order
intermodulation dynamic range
Increases the real sensitivity of antennareceiver system
Increases input selectivity of the receiver
Allow to exclude switchable analog filters from
the SDR system
Adds direct flexibility control over the antenna
parameters from SDR system control software
SDR-based Radio systems
IN TRANSMITTING MODE
combination of SDR system and the proposed antenna will
improve the following characteristics of the RF system:
Increases battery life or allows to reduce dimension
and mass of the battery
Rejects side-oscillations emitted by the transmitters
(harmonics, sub-harmonics, intermodulation oscillations, the
combination oscillations) ), thus eliminating the need to
apply additional filters;
Reduces levels of band noise oscillations beyond the
antenna bandwidth
Ability to combining the multiple transmiting antenna
systems in one array for extending frequency coverage
range
Decreases the bilateral influence from simultaneously
worked and nearby located transmitter, which also
leads to a decreasing bilateral intermodulation
oscillations;
GRAT-Antenna: Solving essential problems
in RF communications (1)
VHF is a Line-of-Sight system: two stations can talk to each other
assuming that they are tuned to the same frequency and they can "see" each
other (from a radio point of view). If one of the station’s antennas is below the
horizon of the other station communication becomes unstable or completely
impossible. The situation becomes worse because of the spurious, unwanted
emissions and intermodulation distortion consist in transmitted radio signals.
Modern receiving and transmitting radio equipment usually has
broadband transmit and receive channel. Current methods of quality matching
the output stage of the transmitter to the antenna-feeder arrangement do not
entirely resolve the problem. By reducing the spurious emissions of the radio
transmitting devices we can reduce electromagnetic pollution of the
atmosphere. In addition, the decline in spurious emissions actively lessens the
utilization of the frequency bandwidth resource.
Being tuned to the same frequency means that both stations are tuned
to the same pre-defined frequency within the occupied band. These predefined frequencies are separated by agreed "spaces", (expressed in KHz.). The
spaces ensure that communications taking place on adjacent pre-defined
frequencies do not interfere with each other.
If transmitted signal has high power emission level stations mast be
separated by certain distance to prevent unwanted interferences and frequency
overlapping. This is dictated by nature of physics of radio wave propagation and
antennas wide passband. The need of such channels separation brings
limitation of station density per covered area and difficulty to communication
between network users or even make it impossible due cannels overload.
When bands are crowded with strong signals, the
ability to hear a weak signal a few KHz away from an
exceptionally strong signal is what separates a decent
receiver from a superior receiver. Such problems and
many other can be solved with our antenna.
Timeline of the problem
Originally the spacing between the frequencies was set to
200 KHz, providing just 70 channels between 118-132 MHZ (band in
1947).
In 1958, the spacing was reduced to 100 KHz, doubling the
number of channels to 140. In 1959 the upper limit of the some
band was expanded to 136 MHz, giving us another 40 channels,
bringing the total to 180. In 1964, the channel spacing was halved
again to 50 KHz, resulting in 360 channels being available.
These dates show not only customer ever increasing hunger
for frequencies, but also the evolution of radios itself. In the 1950s
no radio set would have been suitable for work with 50 KHz spacing.
By 1964, 50 KHz was the standard. The channel spacing was
further cut to 25 KHz in 1972, doubling the available channels to
720. Seven years later, in 1979, the upper limit of the band was
once again expanded, this time to 137 MHz and this delivered
another 40 channels, bringing the total to 760.
In 1995 Today, channel space is 12.5 KHz and the proposal
was made to reduce the channel spacing to 6.25 kHz in year 2013.
GRAT-Antenna: Solving essential problems
in RF communications (2)
The range of the system is largely determined by terrain and the power source of radio emission. The standard
average value range in the open space is about 10 - 15 km for the 5W transmitter. The most unpleasant effect of
blocking the receiver is very strong single signal lying outside the channel received and third-order intermodulation due
to the proximity of the two strong signals, separated in frequency in the band are listening to radio (IMD3).
The picture below represent emission spectrum of standard antenna during transmitting mode.
Intermodulation, spurious and
unwanted signals
1 - Channel bandwidth
2 -Unwanted emission
3 - Spurious emission
4 - Combination oscilation
5 - Harmonics emission
6 - Sub-harmonic frequency
7 - Out-of band signal emission
8 - Out-of-band noise emission
Virtually all modern types of antennas are designed on the basis of general provision that for effective
signal transmission and reception an antenna system shall have dimensions of about 1/2, 5/8 or a 1/4 wavelength.
At the same time take into considerations that reception and transmission of information is done using narrowband signals, so the actual bandwidth of the antenna system may be equal to the width of the spectrum used in
the work of the signals. In practice, this means that if we provide work on one frequency, it is necessary to
implement an effective antenna system demonstrating selectivity at a given frequency and with the required
bandwidth. Working in a wide range of frequencies dictates to use knowingly wideband antenna system. This
requires additional arrangements to improve the parameters of the electromagnetic compatibility (EMC) of
connected equipment in order to maintain equipment working capacity in case of arrival to the input of the
receiver or transmitter output signals from external sources of interference or noise.
GRAT-Antenna: Solving essential problems
in RF communications (3)
In the RF diapasons the effective sizes of antennas cannot be less than some critical size. As a consequence,
we have to choose between optimal antenna parameters and the required dimensions of antennas.
In course of last 10-15 years, the design of equipment for transmitting and receiving of radio signals moved
to a new level, associated the widespread use of digital signal processing techniques. However, this does not
eliminate the need for analog components and matching them with a digital signal processing components.
Nevertheless, the concept of the Software Defined Radio (SDR) becomes more of a reality and after SDR
cognitive radio (CR) technology will be the next major step forward to enable the development of more effective
radio communications systems.
Feature of these systems is tendency to reduce the use of analog signal processing units what may degrade
performance of the whole system.
The problem of conversion received wideband analog signal into a frequency range suitable for further
conversion into a digital form is one reason to use such methods in the development of radio receivers . As a
result, remain unexplored features and capabilities of the input stages of such a system in a wide range of
frequencies and with different levels of signals that are present at the input of the radio system
Now, in use already existed and also new devices in developing, for over-horizon communications at
frequencies up to 30 MHz, and for line-of-sight communication at frequency range from 30 MHz to 500 MHz.Also
known, the HF/VHF networks require special considerations in frequency assignments. The antenna tuning limits
the range of frequencies allowed. The farther the frequencies are dispersed from the center or tuning frequency,
the poorer the quality of the circuit.
Some networks must use hopsets restricted to a narrow distribution of frequencies, and networks that are
subject to high level jamming require maximum dispersion of frequencies in the hopset. The main drawback of
wide dispersion of frequencies is poor system quality. The poor quality is due to lower radiated power from the
antenna when the hops are on frequencies at the specified limits of the bands.
GRAT-Antenna: Solving essential problem
in RF communications (4)
Regarding to the Combat Net Radio (CNR) Frequency Management, the Battled Spectrum Management assigns
the maximum number of frequencies available in the area of operation and spreads the frequencies in the hopsets
across the widest possible band to optimize Electronic Counter-CounterMeasures (ECCM) capabilities. Spreading the
frequencies across the spectrum is more important than increasing the total number of frequencies available. Smaller
number of frequencies distributed over a broadband range, better protected from the jamming devices, compared
with a large number of frequency allocated for narrowband. Thus, the development and use of radio equipment to
operate in this mode will continue.
As a good example, is the Joint Tactical Radio System (JTRS). It is planned to be the next-generation voice-anddata radio used by the U.S. military in field operations after 2010. And, therefore, development and production of
efficient small-sized radio communication systems that meet modern requirements remains actual.
The properties of GRAT-antenna allow working in wideband range with different location of central frequency
and narrow band pass if needed.
GRAT-Antenna: Solving essential problems
in RF communications (5)
1. Produces controlled Amplitude-Frequency-Phase noise signal in the frequency band equal to ∆ = 1% of
the average frequency with emission depended on jammer power.
2. The antenna realize the benefits of ability to suppress specific source signals without disrupting other
communication systems with different working frequencies
3. Fixed-Frequency operation, while ensuring signal filtering / interference located outside the reception band,
since the antenna bandwidth =0.010. At the same time, the standard quarter-wave vertical antennas have
a bandwidth of 20-200 times wider than our proposed antenna;
4. Working in the frequency scanning, which can be purposefully changed with simultaneous provision of
filtering signals that lie outside of the antenna band pass.
5. The antenna, in addition to the reception or emission of signals performs the same function of a tunable
narrowband band pass filter
6. When the proposed antenna combined with SDR system , the antenna can play role tunable receiver
preselector, which you can control by settings of SDR system itself;
7. The antenna increases the receiver dynamic range of third-order intermodulation value IMD3  3 x A, dBa,
where A - fading out of bandwidth antenna, and can be no less 20 dB on HF and VHF band.
8. Receivers SNR improving approximately 2 times
9. The compact dimensions of the antenna, especially vertical dimension
10. The antenna designs have multiple resonant frequencies, and are effective over a broad range of
frequencies.
The GRAT antenna has high Q-factors and resonate with greater amplitudes at the resonant frequency. But from
other side high Q assumes a narrow bandwidth of resonant frequencies and lower rate of energy loss. Fast
electronics tuning allows to distribute equal emitted energy with broad frequency overlap.
Therefore, a high Q tuned circuit in a radio receiver has more selectivity, does a better signal-filtering from other
stations that lie nearby on the spectrum. The transmitting antenna with high Q value oscillates in a narrow
bandwidth, so it is more stable and emits more energy per Hertz.
GRAT-Antenna: Implementation
Police, ambulance,
firefighters
Ultra-Portable Highly-stable
communication devices for
emergency services. The
design of antenna allows to
build more efficient network.
The Federal Communications Commission has mandated all
public safety and business industrial land mobile radio (LMR)
systems operating in the 150-512 MHz radio bands to cease
operating using 25 KHz efficiency technology and begin
operating on channel bandwidths of 12.5 KHz or less as of
January 1, 2013.
This mandate affects any users operating at VHF (150-174
MHz) (we can narrow antenna bandwidth around 150 KHz to 75
KHz on given frequency range) and UHF (421-512 MHz) (we can
narrow antenna bandwidth around 250 KHz to 200 KHz on given
frequency range) utilizing Part 90 frequencies.
This includes but is not limited to public safety, public
works, utilities, hospitals, higher education, and K-12 schools.
After January 1, 2013, licensees not operating at 12.5 KHz
efficiency will be in violation of the Commission's rules and
could be subject to FCC enforcement action. The next
generation of our antenna with contemporary equipment will
improve operating benefits and decreasing device dimensions.
Although a deadline for the second phase of narrowbanding,
conversion to 6.25 KHz channel efficiency, has not been specified
by the FCC for VHF/UHF licenses, a deadline has been
established which requires 700 MHz channels to operate at 6.25
KHz efficiency by January 1, 2017.
GRAT-Antenna: Implementation
Emergency Situations in remote areas
and areas of natural disaster.
Huge improvement to the durability and
mechanical stability when working in forested
areas, strong winds and other natural disasters.
Existing long-whip antennas are highly
vulnerable to the mechanical stress. The
proposed antenna due to its compact nature
and mechanical strength may be a worthy
substitute for them, since it is easier to protect
from the unwanted environmental and other
external stresses. In this case, it is maybe not as
effective as classical antennas.
High-speed transport, air, land, sea.
Small size of the proposed antenna can
provide high quality and streamlining to
create it as an element of body design of a
moving object.
Security Systems, where the
antenna can be used as part of the
natural environment for stealth
where necessary.
Automatic unattended beacons, emergency
beacons operating in harsh climatic
conditions. The small size allows it to establish as
an element of housing design, easy to protect from
external influences while maintaining high efficiency.
GRAT-Antenna: Implementation
Mini, micro and nano satellites. Place of installation: metal panels of heat
exchangers, solar batteries. Objective: Reduction in size of satellites with
high efficiency transceivers antenna systems. On satellites, various electronic
devices, with different purpose in design, frequency range and power
transmitting antennas, which create strong electromagnetic fields. All this
equipment is operated in a very limited extent, which leads to strong
interference. Using the proposed tunable resonant antenna will eliminate the
existing problem on the above described electromagnetic compatibility.
Small size make it possible to place several of the proposed tunable antennas
operating at different frequencies without interference. This allows for the
unique physical experiments on the multi-frequency transillumination of the
ionosphere over a wide frequency range. Possibility of establishing
narrowband communication channel for using satellite in repeater mode.
With compatible "on ground" equipment such communication session will
be precise directed to the object and practically undetected by surrounding
monitoring stations.
The mini satellite on lower orbit relative to targeted satellite
orbit can generate special interference signal to simulate
malfunctioning of the communication channel or falsify GPS signal
for any reason. Because of GRAT-antenna strong EMF in near
zone and small, undetectable, dimension such satellite can be
located near any orbital object to block receiving control signal.
GRAT-Antenna: Implementation
RCIED Jamming
Using the proposed antenna with various existing generators
interference-type jammers. The existing jamming systems now
use full-length whip antenna for lower frequency band and such
jammers are “power hungry” and require big amount of space.
The used type of antenna is not efficient enough to generate
the required field strength in the near zone at an affordable
energy. The proposed antenna because of its natural
properties has a much greater intensity near-field compared
with counterparts with equal energy. In this case, it is, as
mentioned above, is more compact, durable and better
mechanically implemented.
Genesys had designed RCIED Jammer
based on the GRAT-Antenna. The use of
GRAT-Antenna in this new jammer allows
to fully explore and utilize its unique
features and capabilities.