Military Satellite Communications Research Articles

Theoretical and Experimental Investigation of N-Bit Reconfigurable Retrodirective Metasurface

The PIN diode-based N-bit reconfigurable retrodirective metasurface (N-bit RRDM) is a next-generation retro-reflector that offers the advantages of effective electronical control of the retro-reflection angle, low loss, and thin planar structure. However, since the unit cell of an N-bit RRDM is controlled by a quantized N-bit phase (360°/2<sup>N</sup>), it encounters operational errors, such as beam gain reduction and spurious beams. This can be a fatal disadvantage in military radar or satellite communication, which requires accurate beam tracking. This paper theoretically analyzes the operation of the N-bit RRDM by utilizing generalized Snell’s law and array factor theory. The analysis results present the design criteria for an N-bit RRDM that eliminates issues related to beam gain reduction and spurious beam errors. Furthermore, to verify the theoretical analysis results, High-Frequency Structure Simulator (HFSS) full-wave simulation and experimentation are conducted using the 1-bit RRDM.

Satellite navigation method based on high-speed frequency hopping signal

Global navigation satellite system has been widely used, but it is vulnerable to jamming. In military satellite communications, frequency hopping (FH) signal is usually used for anti-jamming communications. If the FH signal can be used in satellite navigation, the anti-jamming ability of satellite navigation can be improved. Although a recently proposed time-frequency matrix ranging method (TFMR) can use FH signals to realize pseudorange measurement, it cannot transmit navigation messages using the ranging signal which is crucial for satellite navigation. In this article, we propose dual-tone binary frequency shift keying-based TFMR (DBFSK-TFMR). DBFSK-TFMR designs an extended time-frequency matrix (ETFM) and its generation algorithm, which can use the frequency differences in different dual-tone signals in ETFM to modulate data and eliminate the negative impact of data modulation on pseudorange measurement. Using ETFM, DBFSK-TFMR not only realizes the navigation message transmission but also ensures the precision and unambiguous measurement range of pseudorange measurement. DBFSK-TFMR can be used as an integrated solution for anti-jamming communication and navigation based on FH signals. Simulation results show that DBFSK-TFMR has almost the same ranging performance as TFMR.

Development of military satellite communications constellations and the US missile attack warning system: modern state and prospects

In the modern world, the armed forces of technologically developed countries are active consumers of satellite information, and in some cases critically depend on it. This primarily concerns Russia and the United States, which have both military satellite constellations for various purposes (in particular, satellite missile attack warning systems), and make specialized purchases from commercial owners and operators of satellite systems in the interests of their military departments. This article proposes to consider the American military satellite communication systems and missile attack warning systems (MAWS), the reasons and process of their modernization, which took place in 2018-2023, as well as long-term development plans.

Ku band metamaterial absorber for stealth applications against Radar and Military Satcom

Ku band metamaterial absorber for stealth applications against Radar and Military Satcom

A novel ultra wideband circularly polarized stacked cylindrical dielectric resonator antenna with modified ground plane

In this paper, two identical Cylindrical Dielectric Resonator Antennas (CDRA) are stacked together to achieve Circular Polarization (CP). Ultra wideband impedance bandwidth and wide axial ratio bandwidth is achieved by three factors: stacking of similar DRs, stepped conformal microstrip feed line which will generate orthogonal modes and new partial ground plane with circular rings. Measurement results show that the proposed stacked Cylindrical CPDRA achieves an Impedance Bandwidth (IBW) of (S11 < −10 dB) of 72.48% (3.65–7.8 GHz) and Axial Ratio Bandwidth (ARBW) (AR <3 dB) of 44.12% (4.38–6.86 GHz), respectively. In addition, the proposed antenna shows dominant Left Hand CP with gain ranges from 1.4 to 6.5 dBic with maximum radiation efficiency of 93.3%. The advantages and novel points of proposed research work is as follows: (i) The novel configuration of stacking CDRA's along with stepped microstrip feed enhances ARBW, (ii) New proposed partial ground plane with two circular rings provides enhancement in IBW, (iii) Simple design and small height of DRs produces enhanced IBW, ARBW, Gain and Efficiency. Furthermore, by changing the position of circular rings on ground plane, the proposed antenna provides dominant LHCP to RHCP conversion and achieves polarization reconfigurability. The proposed antenna configuration covers the frequency range of applications of C-band and military satellite communication.

Conflict Analysis of Iranian Military-Communications Satellite Launches

Conflict Analysis of Iranian Military-Communications Satellite Launches

An uplink power optimization solution for satellite HUBs station based on closed-loop control algorithm

In this paper, we present a power optimization solution based on the automatic power control method using a closed-loop algorithm for the uplink power control device (UPC) of the satellite communication HUB station. The results are evaluated by theoretical analysis and validated by simulation model on Matlab software, finally the model has also been used in the UPC device and tested in practice. The simulation process, and the test is carried out under the impact of varying rainfall on the wave path, the results are compared with the solutions that have been and are being used to demonstrate the effectiveness of the solution. This paper is the research product of the project "Researching, designing and manufacturing the uplink power controller military satellite communication system".

Communications satellites in Canadian security policy: History and prospects

This article traces Canada’s early interest in space, before turning to its late 1960s decision to focus on a domestic, commercial/civilian communications satellite system in geostationary orbit and the subsequent decline in Canada’s military space efforts. It then highlights the wake-up call of the 1991 Gulf War, which demonstrated the critical importance of military communications satellites to future operations, and the steps Canada has taken to gain assured access to such satellites in the decades since. The final section outlines recent advances in low Earth orbit satellite communications (LEO satcom) and the ways in which these systems can address shortfalls in their geostationary cousins. Drawing reference to a new international security environment, it concludes that Canada should move expeditiously to incorporate LEO satcom into efforts to address the growing imperative of military satellite communications in the Canadian Arctic.

Peano–Gosper, Koch and Minkowski fractal curves-based novel hybrid antenna using modified partial ground plane for multi-standard wireless applications

This paper presents the unique structure of a hybrid antenna with a blend of Peano–Gosper, Koch and Minkowski curves using a modified partial ground plane for multi-standard wireless applications. Initially, the Minkowski and Koch curves are amalgamated by using a versatile mathematical tool called Iterative Function System (IFS), and furthermore, their resultant structure is superimposed on each segment of Peano–Gosper curve to obtain the novel geometry of hybrid fractal antenna named Gosper–Koch–Minkowski Hybrid Fractal Antenna (GKMHFA). The partial ground plane with 50 Ω transmission line fed is used to analyse the performance of designed structure and found that it exhibits five different frequency bands above 9 GHz in the frequency range 1–20 GHz. Consequently, to attain the frequency bands below 9 GHz with enhanced bandwidth and reflection coefficient, the partial ground plane has been modified. The proposed antenna with the modified ground plane reveals seven distinct frequency points 1.5, 3.4, 8.6, 12.2, 14.1, 15.3 and 18.9 GHz with a maximum bandwidth 5.0 GHz along with improved reflection coefficient i.e. −45.65 dB at 1.5 GHz. The proposed antenna also reports positive gain and stable radiation patterns in the operational frequency bands, which make it a proficient candidate for the multi-standard wireless applications such as GPS, terrestrial communication, PCS, UMTS, advance wireless services, Bluetooth, WLAN, Wi-Fi, Wi-MAX, military satellite communication, television broadcasting, broadcasting satellite, FSS, Ku-band and K-band.

A Compact Triple Band Antenna for Military Satellite Communication, Radar and Fifth Generation Applications

A compact triple band antenna by using etching slots technique in the radiation element is presented in this paper. The proposed antenna is designed to target three different frequencies: 7.5 GHz (military satellite communication), 9 GHz (radar applications) and 28 GHz (fifth generation applications). The fabricated prototype of the antenna has overall dimensions of 13x12.8x1.6 mm3. Measurements were carried out to validate the simulation results. The impedance bandwidths are 259 MHz (7.435-7.695 MHz), 355 MHz (8.86-9.221 MHz) and 2.67 GHz (26.79-29.433 GHz) with return loss less than -10 dB. Furthermore, the suggested antenna provides a gain of 3.96 dBi, 3.05 dBi and 5.86 dBi at 7.5 GHz, 9 GHz and 28 GHz respectively. Therefore, the results demonstrate that the proposed triple band antenna can be used for military satellite communication, radar applications and is a good candidate for the future 5G applications.

대형팬 구동 환경에서의 이동식 위성통신 안테나 진동 저감 방법론

A large offset antenna, which is used as military satellite communication terminal, is generally operated in extremely harsh environments. As a very large reflector is mounted, the reflector has to undergo communication performance tests for external forces such as wind vibrations. Wind vibration tests have been replaced with artificial wind tests conducted using large fans because of space and cost constraints. Therefore, there is a need to improve the communication performance through vibration reduction for the excitation force caused by artificial wind. In this study, the frequency characteristics were verified by analyzing the excitation force caused by artificial wind, and a vibration reduction methodology was presented based on the finite element model which was verified via experiments. This study suggested a general vibration reduction approach for large offset antennas and is expected to be useful in industries.

Askeri Uydu Haberleşmesi için Mikroşerit Yama Anten Tasarımı

In this paper, a broadband and high gain microstrip patch antenna was designed with a microstrip feeding technique to operate in the electromagnetic spectrum in the X band in the frequency range of 7.2 8.4 GHz, which is allocated for use in military sate llite communication. In this design, Rogers RT / duroid 5880 material with a thickness of 3.175mm, dielectric coefficient of 2.2 and tangent loss (tan δ) of 0.0009 was selected and simulated on the HFSS program. Since the antenna sizes calculated by numerical methods are difficult to adjust to operate in appropriate frequency ranges, the dimensions of the antenna designed using the genetic algorithm, which is a part of artificial intelligence optimization algorithms, have been optimized to work in the desir ed frequency ranges. According to the designed antenna simulation results, it operates in the frequency ranges of 7.06 8.41 GHz and the designed antenna has a bandwidth of approximately 1.35 GHz = 17.25%. At 7.825 GHz center frequency, the antenna's gain is approximately 7.2 dB. In order to increase the bandwidth of the designed antenna, a second antenna design was realized by optimizing the dimensions of the antenna covered with copper and microstrip feeding. The second antenna designed as a result of th e changes made on the antenna operates in the frequency ranges of 6.74 9.69 GHz and the designed antenna has a bandwidth of approximately 2.95 GHz = 37.7%. At the central frequency of 7.825 GHz, the antenna's gain is approximately 6.63 dB.

Frequency-Selective Surface-Based Compact Single Substrate Layer Dual-Band Transmission-Type Linear-to-Circular Polarization Converter

In this article, a compact dual-band linear-tocircular polarization converter designed on a single-layer substrate is proposed. The unit cell of the converter has a size of 3.72 × 3.90 × 1.52 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (0.0072λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , λo is calculated with respect to 20.67 GHz). The converter consists of split rings and a pair of metallic strips printed on both sides of a single-layer substrate for dual-band operation. The proposed converter has a measured 3-dB axial ratio bandwidth of 5.56% (20.10-21.25 GHz) in the lower band and 3.97% (29.12-30.30 GHz) at the upper band. The converter transmits a right-hand circularly polarized (RHCP) wave at the lower band and left-hand circularly polarized (LHCP) wave at the upper band for a linearly polarized (LP) incident wave. The characteristics of the polarization converter are validated by integrating an array of 7 × 7 elements of its unit cell in the endfire direction of a dual-band LP dipole antenna operating in the same frequency bands such as that of the polarization converter. The antenna integrated with the polarization converter exhibits measured circularly polarized (CP) bandwidths of 7.80% and 6.57% in the lower frequency band: 20.10-21.75 GHz and the upper frequency band: 29.4-31.4 GHz, respectively. The integrated antenna can act as a feed source of a high-gain dualband transmit array for uplink (30.0-31.0 GHz) and downlink (20.2-21.2 GHz) of Ka-band military satellite communication.

Method for Determining the Parameters of Interference Affecting the Input of the Repeater Trunk

Military satellite communication networks operate under the influence of enemy radio suppression systems. To suppress the network, it is necessary to put a deliberate interference either at the entrance of the trunk of the communication repeater, or at the entrance of satellite communication stations operating in this network. Taking into account the peculiarities of building a satellite communication network, the most likely effect is the radio-electronic suppression complex at the entrance of the repeater trunk. The article presents a method for determining the parameters of interference affecting the input of the repeater trunk

Performance enhancement of nested hexagonal ring‐shaped compact multiband integrated wideband fractal antennas for wireless applications

In this paper, nested hexagonal ring-shaped fractal antennas are designed and investigated which are different from each other in patch orientation. Initially, the multiband integrated wideband hexagonal nested ring antenna is designed (antenna-I). To improve the multiband/wideband behavior, the patch orientation of antenna-I is changed to −60°/60° (antenna-II), −120°/120° (antenna-III), and −180°/180° (antenna-IV). Antennas are designed on low cost FR-4 glass epoxy substrate with relative permittivity of 4.4 and overall dimension 30 × 30 × 1.6 mm3. Comparison among antennas have been made and found that the antennas with negative orientation exhibit better results in terms of bandwidth, impedance matching, number of frequency bands, and gain. Designed antennas have been compared with each other and found that antennas-II and III are better in performance as compared to antennas-I and IV. Antenna-II exhibits wider bandwidth of 1.26 (2.52-3.78 GHz), 2.75 (4.03-6.78 GHz), and 6.1 GHz (7.82-13.92 GHz) with maximum gain of 7.14 dB. Similarly; antenna-III exhibits the bandwidth of 340 MHz (1.92-2.26 GHz), 820 MHz (3.04-3.86 GHz), 4230 MHz (5.38-9.61 GHz), and 3040 MHz (10.41-13.45 GHz) with a maximum gain of 6.19 dB. Prototype of the designed antennas with satisfactory orientations are fabricated and tested for the validation of results. Simulated and measured results are also juxtaposed and observed in good agreement with each other. Antennas exhibit bidirectional and omnidirectional pattern in E-plane and H-plane, respectively, also the radiation efficiency of antennas are in acceptable range from 75% to 95%. Due to the wider bandwidth of designed antennas, they can be used for different wireless standards such as Advance Wireless Services AWS-1, AWS-2, AWS-3, Wi-MAX, WLAN, X-band satellite communication, point-to-point wireless applications, ITU band, military satellite communication, television broadcasting, and military land and airborne systems.

A Novel Low Profile Rectangular Microstrip Patch Antenna for L-Band Applications Using High Permittivity Substrate

A novel low-profile and miniaturized patch antenna on a substrate material of high dielectric constant has been designed, fabricated and tested in an indigenous laboratory. It is highly important to reduce the size of patch antenna as it limits the reduction of the sizes of the devices using this antenna. A number of techniques have been given for the size reduction of patch such as DGS (Defected Ground Structure), use of fractals and the use of metamaterials but in this paper the technique of high permittivity substrate has been implemented. The substrate as well as this conventional antenna has been prepared locally in Pakistan. A ceramic material of chemical composition {(Sr0.5Pb0.25Ca0.25)-Tio3-3Bi2O3.TiO2} having a high dielectric constant has beenused in the substrate of the antenna. The fabricated prototype was investigated experimentally for important parameters using Vector Network analyzer. The total measure of the antenna is 20.5x26.5x1.5 mm3. The antenna presented a large bandwidth of 186 MHz (1070-1256 MHz)in L-Band with a Return Loss of 21.10 dB at resonance. The VSWR (Voltage Standing Wave Ratio) remained under the standard value of 2 in the whole operating range. The proposed antenna may be employed in GPS (Global Positioning System) devices, Amateur Radio, Terrestrial Mobile Communication, Aeronautical and Maritime Mobile and other Military and Low Earth Orbit Satellite Communications.

Secure Satellite Communication Digital IF CMOS $Q$ -Band Transmitter and $K$ -Band Receiver

This paper reports the first CMOS RF integrated chipset for secure commercial and military satellite communication enabling next-generation low size, weight, and power (SWaP) terminals. This chipset is a significant departure from current terminals relying on individually qualified IC components by taking advantage of advanced CMOS integration. The transmitter and receiver designs are digital IF architectures that rely on the higher sampling rate capability of CMOS, and precise digital filtering, quadrature frequency translation, and frequency hopping/de-hopping. The CMOS transmitter is a fully integrated system-on-chip (SoC) design, while the receiver consists of a co-designed RF and digital IF receiver. The Tx/Rx uses a 200-/300-MHz double data rate (DDR) interface driving/receiving a complex frequency translator with sub-hertz frequency hopping resolution via on-chip numerically controlled oscillators (NCO). The transmitter includes two 12-b return-to-zero (RZ) digital-to-analog converters (DACs) and quadrature modulator to form a single-sideband (SSB) upconverter achieving >30-dB spur rejection. An RF upconverter with an X2 multiplier drives a 24-dBm $Q$ -band CMOS stacked power amplifier (PA). The RF receiver implements a matched inverter amplifier (IA) followed by a complementary active balun that current drives a passive mixer with a trans-impedance active combiner. The digital IF receiver includes a high-linearity variable gain amplifier (VGA) that drives an 8 $\times $ time-interleaved 1.2-GS/s analog-to-digital converter (ADC) with dc offset and gain calibration with an embedded digital receiver. Both the transmitter and receiver use a 1.5-GHz IF signal. The combined CMOS chipset was demonstrated with a current military satcom modulation and protocol and achieves 5 $\times $ lower power consumption and size versus the current configuration.

A compact wide-slot UWB antenna with reconfigurable and sharp dual-band notches for underlay cognitive radio applications

This paper presents a compact wide-slot ultrawide-band (UWB) antenna with reconfigurable and sharp dual-band notches compatible with the underlay cognitive radio systems. The antenna slot and tuning stub are reshaped in such a way that the proposed antenna operating bandwidth extends along the frequency band specified for UWB applications (3.1-10.6 GHz). In spite of their sharpness, the generated band notches perfectly cancel the interference with the entire 5 GHz wireless local area network (WLAN) frequency band (5.15-5.725 GHz) and that of the military X-band satellite communications downlink (7.25-7.745 GHz). The WLAN band notch is presented by attaching a pair of quarter wavelength parasitic elements to the antenna ground plane, while the other band notch is produced by engraving another pair of half wavelength parasitic elements within the antenna wide slot along the circumference of the antenna tuning stub. The reconfiguration of the band notches is achieved by inserting a pair of PIN diodes for each pair of parasitic elements. The simulated and measured results accentuate the UWB coverage of the proposed antenna, and also verify the reconfigurability and the sharpness of the antenna band notches. Moreover, the antenna has a noticeably stable radiation pattern over the entire band of operation with omnidirectional pattern convenient for portable UWB gadgets.

Fade Margin Estimations for Malaysian Armed Forces Military X-Band Satellite Communication Links

The satellite communication (satcom) operating in X-band frequencies has the potential to enhance communication capabilities of Malaysian Armed Forces (MAF) and the Malaysian National Security Council (NSC). The satcom can be deployed during catastrophic instances, crisis incidences and certainly for the use of military operations. The satcom can facilitate the delivery of critical high-speed data, voice and video services between military bases, headquarters and also military detachments. The paper highlights the predicted fade margin requirements by the Malaysian Military satellite communication in order to accomplish specific operational quality of services (QoS). This is of utmost importance considering that both the uplink and the downlink will be facing severe rain attenuation due to copious heavy rainfall events, typically endured by tropical region countries. A prediction technique, recommendation ITU-R P. 618-12 with value proposed by ITU-R P. 637-6 had been employed in order to generate the desired results. Local data acquired from the Department of Irrigation and Drainage Malaysia had also been utilized in the generation of the fade margin estimations. The findings from the studies can offer insight of how to ensure/ enhance the satellite communication links reliability.

Synthesis and characterisation of novel low temperature ceramic and its implementation as substrate in dual segment CDRA

Li2O-(2-3x)MgO-(x)Al2O3-P2O5 (LMAP) (x = 0.00–0.08) ceramic system was prepared through solid state synthesis route at different sintering temperatures (800–925 °C). A small addition of Al2O3 (x = 0.02) in LMAP ceramics lowers the sintering temperature by more than 100 °C with good relative density of 94.13%. The sintered samples were characterized in terms of density, apparent porosity, water absorption, crystal structure, micro-structure and microwave dielectric properties. Silver compatibility test is also performed for its use as electrode material in low temperature co-fired ceramic (LTCC) application. To check the performance of the prepared LTCC as substrate, a microstrip-fed aperture-coupled dual segment cylindrical dielectric resonator antenna (DS-CDRA) is designed using LMAP (x = 0.02) ceramic as substrate material and Barium Strontium Titanate with 10 wt% of PbO-BaO-B2O3-SiO2 glass (BSTG) and Teflon as the components of resonating material. The simulation study of the DS-CDRA is performed using the Ansys High Frequency Structure Simulator (HFSS) software. A conductive coating of silver is used on the substrate. The simulated and measured −10 dB reflection coefficient bandwidths of 910 MHz (9.07–9.98 GHz at resonant frequency of 9.49 GHz) and 1080 MHz (8.68–9.76 GHz at resonant frequency of 9.36 GHz), respectively are achieved. The measured results of the fabricated antenna are found in good agreement with the simulation results. The prepared material can find potential applications in radar and radio navigation as well as radio astronomy and military satellite communication.