Existing small satellite antenna

Transcription

1 Existing small satellite antenna He & Arichandran, 2001 designed a physically small, aperture coupled patch antenna at GHz (X band). The antenna displays 5.6% fractional bandwidth and a gain 6.5 dbi. NTU, Singapore Mathur et al, 2001 described the design of two patch antennas for the USUsat nano-satellite which is part of the ION-F constellation. Operating frequency 450 MHz (uplink), and 2.26 GHz (downlink) with 20 mm square patch. Utah State University Wincza et al described the mini satellite which dimension is 60x60x60cm 3 and it communicates at 2.025GHz and 8.45GHz. Operational Bandwidth 50 MHz and the microstrip patch is printed on a complex sandwiched structure to increase the bandwidth. Idzkowski et al.,2004 studied ESEO satellite which communicates at 2.080GHz and GHz and bears a total of six microstrip antennas for communications and telemetry. The authors cite a 7 dbi gain for this antenna system, without clarifying whether this gain holds for each antenna separately or if the antennas were grouped in two 3 element linear arrays. Muchalski et al designed a 61.4 mm square patch that was suspended 10mm above the ground plane (air dielectric ). The ground plane measured 60cm 70cm and correspond to the wall size of the spacecraft. Maleszka et al describe briefly the design of a low profile,low gain Mathur et al, 2001 :The design of two patch antennas for the USUsat nano-satellite --Utah State University, USA, 2001 Maleszka et al. 2007:Circularly Polarized Patch Antennas Placed on Minisatellites -Wroclaw University of Technology, Poland. Arnieri et al. 2007:European Student Earth Orbiter (ESEO) small satellite --University of Calabria, Italy. 1

2 Existing small satellite antenna SSTL 2008 developed circular patch antenna which achieved 4.9dBi gain and main lobe beam width equal to Maqsood et al presented dual band, circularly polarized planar antenna for GNSS based remote sensing applications. Operating frequency 1.575GHz and 1.227GHz, their achieved gain 6.3dBi and 4.0dBi. Martinez Rodriguez-Osorio et al proposed a stacked patch with 2 2 sub array antenna for 5.8 GHz for inter-satellite communication. The measured S 11 was dB at the central frequency of 5.8 GHz, even outperforming the simulation predictions. The measured -10 db return-loss bandwidth was larger than 250 MHz, and gain of the sub array was 2.5 dbi, lower than expected, and degrading the resulting axial ratio in the vicinity of broadside. Yasin & Baktur 2013 has been designed a circularly polarized meshed patch antenna for small satellite applications. The proposed antenna consists of two square meshed patches, which generate two orthogonal linear polarizations at two slightly different frequencies. Sosa-Pedroza et al developed a 2.4 GHz cross rhombic antenna to be used in a CubeSat. The dimension (100 mm 100mm 5.6mm) and weight (154 gm) of the antenna is comparatively large for using small satellite applications. Surrey S-band Patch Antenna Yasin & Baktur 2013 :Meshed Patch antenna for small satellite Martinez et al : Universidad Politécnica de Madrid, Spain Nascetti et al. 2014: Tigrisat developed at the School of Aerospace Engineering of Sapienza University of Rome, Italy 2

3 Existing small satellite antenna Nascetti et al proposed high-gain s-band patch antenna system for earth-observation cubesat satellites. The antenna consists of four rectangular patches properly excited in order to have the maximum gain. Erika Pittella et al proposed Reconfigurable S-Band Patch Antenna System for Cubesat Satellites. Tigrisat S band antenna Suari, J.P et all 2001 developed Cube-Sat class pico-satellite using UHF/ VHF dipole antenna. (Moghaddam et al., 2004) used a separated turnstile antenna (STA) to obtain saddle-shaped and hemispherical patterns for small low-earthorbit (LEO) satellites at VHF and UHF bands. This STA is an array of four monopoles that are mounted symmetrically on the satellite and are electrically driven in phase-quadrature. The antenna is built with 55 cm long wire elements and it resonates at 130 MHz. UoSAT (2011) spacecraft used VHF and UHF transmitters with corresponding wavelengths of 2m and 70cm on structures typically measuring 58X 35 X 35cm. body of these spacecraft was shorter than the wavelengths involved. Suari, J.P et all 2001 UoSAT (2011) 3

4 Existing small satellite antenna Nascetti et al proposed high-gain s-band patch antenna system for earth-observation cubesat satellites. The antenna consists of four rectangular patches properly excited in order to have the maximum gain. Erika Pittella et al proposed Reconfigurable S-Band Patch Antenna System for Cubesat Satellites. Tigrisat S band antenna Suari, J.P et all 2001 developed Cube-Sat class pico-satellite using UHF/ VHF dipole antenna. (Moghaddam et al., 2004) used a separated turnstile antenna (STA) to obtain saddle-shaped and hemispherical patterns for small low-earthorbit (LEO) satellites at VHF and UHF bands. This STA is an array of four monopoles that are mounted symmetrically on the satellite and are electrically driven in phase-quadrature. The antenna is built with 55 cm long wire elements and it resonates at 130 MHz. UoSAT (2011) spacecraft used VHF and UHF transmitters with corresponding wavelengths of 2m and 70cm on structures typically measuring 58X 35 X 35cm. body of these spacecraft was shorter than the wavelengths involved. Suari, J.P et all 2001 UoSAT (2011) 4

5 Design Specification Typically, Small satellite rely on VHF/UHF communication systems with deployable monopole or dipole antennas for low bitrate uplink and downlink (telecomm ands and telemetry) while, for high bitrates, S-band is among the favorite choices as the range MHz is one of the International amateur satellite frequency ranges allocated by the International Telecommunication Union. Parameter Frequency Bandwidth Size Thickness Substrate Polarization Desired 2400 MHz 200 khz 80 mm 80 mm (Max) 20 mm (Max) Rogers RT/Duroid (Rogers 5880, ε=2.2, tanδ=0.0009) High reliability characteristics for aerospace application. Right Hand Circular Polarization (RHCP) Peak Gain Antenna weight 3 db Axial Ratio Beamwidth 6 dbic 100 ~ 150 gm >120 degrees 5

6 Flowchart of the Design Start Specifications & Literature Review Get Antenna Specifications Study Antenna Literature Analyze Existing Related Antennas Choose appropriate Simulating Software Be accustomed to Simulation Software Determination of Material, Appropriate Model & Design Dimensions D Simulation Consider Targeted Frequency Optimization Simulate in EM Simulator Examine Performances B A 6

7 Flowchart of the Design (Cont) B A No Satisfactory Results? Yes Simulate to meet other Frequencies Optimization Examine Performances No Satisfactory Results? Yes Fabrication & Measurement Prototype Development Scattering Parameter Measurement No Satisfactory Results? Yes Different Characteristics Measurements No Satisfactory Results? End Yes 7

8 Design Method D14 D13 D12 D11 D15 D16 D17 D18 D10 D9 D8 D7 D6 D1 D2 D3 D4 D5 Ground Ground Patch Parasitic Element Ground Ground Xf,Yf Due to space activities, Rogers 5880 material has chosen for this design. The initial design was chosen based on the literature that provided circularly polarized radiation in the broadside direction. The geometric parameters of this structure has adjusted to tune the return loss and bandwidth over S band frequency using the RCPSO algorithm. The patch consists of four asymmetric V-shaped slit (Southern Cross shaped patch) with rectangular parasitic strip. The patch will be connected through a drilled hole in the substrate and ground plane. After getting the desired results, the proposed prototype has fabricated in UKM microwave lab through LPKF PCB(S63) prototype machine. The fabricated antenna has tested in near field anechoic chamber in UKM microwave lab. Performance of this compact small satellite antenna product for commercial application is compared with other existing products. Ref: M. T. Islam, Mengu Cho, M. Samsuzzaman, S. Kibria, Compact Antenna for Small Satellite Applications, IEEE Antennas and Propagation Magazine, Vol. 57, Issue no. 2, pp ,

9 Manufacturing process flow Antenna design PCB fabrication Antenna construction Lab testing Final measurement Licensing End 9

10 Measurement Antenna design PCB fabrication Antenna construction Lab testing Final measurement Licensing End 10

11 Initial and Optimized dimensions for the S band antenna D14 D13 D12 D11 D15 D16 D17 D18 D10 D9 D8 D7 D6 D1 D2 D3 D4 D5 Dimension Initial value Optimized value D D D D D D D D D9 5 0 D D D D D D D D D

12 Ramped Convergence Particle Swarm Optimization Problems: Premature convergence, Curse of dimensionality Solution: RCPSO, Heterogeneous boundary condition, K- dimensionality and multistart approach Any complex design can be expressed a set of dimensions expressed in vector form. A population size is chosen based on computational power used for optimization. This process is repeated until desired performance is achieved. Equations used to update the particles are: V i+1 =wv i +c 1 r 1 (D global_best -D i )+c 2 r 2 (D local_best -D i ) D i+1 =D i +V i+1 Ref: Salehin Kibria, Mohammad Tariqul Islam and Baharuddin Yatim, New Compact Dual-Band Circularly Polarized Universal RFID Reader Antenna Using Ramped Convergence Particle Swarm Optimization, IEEE Transactions on Antennas and Propagation, vol. 62, pp RCPSO uses acceleration coefficients c1, c2 and w to tune the nature of the optimization from exploratory or exploitive. They are used to update the population members and move them towards population members with better performance. 12

13 RCPSO Algorithm Flowchart Start Assign initial antenna design and its dimensions Initialize c 1, c 2, w, population, gen_max, n_shift, active dimensions, global and local best values Evaluate fitness for all valid population members Update local global best if fitness is better Set first n_shift active dimensions as inactive. Set next n_shift inactive dimensions active. Initialize population Apply equations (1) and (2) to all population members If any population member violates lower dimensional bound, reset violating dimension to zero If any population member violates upper dimensional bound, set population member as invalid N Y Termination criterion met? Y Output global best N gen_max generations completed for current set of active dimensions? 13

14 Initial and Optimized Result 14

15 High gain antenna prototype The Prototype Ground Parasitic Element Patch Ground Ground Xf,Yf Ground Operating Frequency Ranges Dimension The proposed S band antenna performance specifications 75 MHz (2.385 GHz-2.46 GHz) mm (Patch) mm(antenna Dimension) Gain 7.27 dbi Geometry & Photograph of the Proposed Antenna Maximum Radiation Efficiency Radiation Patterns Polarization 3 db axial ratio beamwidth % Directional Right Hand Circular Polarization (RHCP) >

16 Results and discussion Measured reflection coefficient of the antenna Simulated and measured 10-dB return loss bandwidth are 2.48 % ( GHz) and 3.09 % ( GHz) respectively. 16

17 Axial ratio of the antenna The Simulated 3-dB AR bandwidth is 19 MHz and measured bandwidth is also near about 21 MHz. 17

18 Axial ratio pattern of the antenna (a) XZ plane (b) YZ plane The 3 db axial ratio bandwidth is (-60 0 to 88 0 ) at XZ plane and (-72 0 to 62 0 ) at YZ plane respectively at 2.40 GHz. 18

19 Radiation Pattern (a) The measured and simulated radiation patterns (in dbi) of the proposed antenna (a) XZ plane and (b) YZ plane are at 2.40 GHz. the antenna produces RHCP waves in the >0 half spaces, near the +z direction of which the radiation fields have larger RHCP to LHCP ratios and hence smaller ARs. The measurement agrees quite well with the simulation, especially for RHCP waves in the Z>0 half space. In the measured data for 2.40 GHz, the forward (+z direction) RHCP wave at least 27 db larger than the backward (- z direction) RHCP wave and 17 db larger than the backward LHCP wave. (b) 19

20 Gain and Efficiency The gain in the positive Z axis direction was measured at 7.27 dbi. The radiation efficiency against frequency and more than 95.89% radiation efficiency observed at 2.4 GHz. 20

21 Distribution +Y +Y -X -X a 0 degree b 90 degree -Y +X -Y X c 180 degree d 270 degree The simulated surface current directions at 2.4 GHz, viewed from the patch radiator and rectangular slit are shown in this Figure as the phase changes from 0 0 to The 0 0 phase reference shows that the dominant radiating currents are +Y directions. For 90 0 phase, the dominant surface currents flow is in the -X direction. A dominant -Y current flows are observed in the phase, which is an opposite current phase direction to 0 0 phase reference. Finally, for the phases, the currents are +X directed, hence the current flows in a counter clockwise and polarization sense is right hand in the 21

22 RHCP polarization Anticlockwise direction 22

23 Parasitic Element 2.4 GHz LHCP Antenna The RHCP antenna can be worked also LHCP antenna by alternate the top and bottom asymmetric V-shaped slit. To create the LHCP patch antenna, the optimized RHCP design has just mirror the antenna with existing parameter. If the RCHP antenna s top and bottom side of two V- shaped slits can replace each other, then LHCP characteristic patch antenna can be designed which explained by surface current distribution. LHCP Antenna G_L=80 Ground Ground G_L=80 Patch Ground Feed Position LHCP Antenna geometric layout Asymmetric V shaped slit Ground Asymmetric V shaped slit 23

24 Continued -Y -Y -X -X a 0 degree b 90 degree +Y +Y +X +X c 180 degree d 270 degree The simulated surface current directions at 2.4GHz, viewed from the patch radiator and rectangular slit are shown in this Figure as the phase changes from 0 0 to The 0 0 phase reference shows that the dominant radiating currents are Y directions. For 90 0 phase, the dominant surface currents flow is in the -X direction. A dominant +Y current flows are observed in the phase, which is an opposite current phase direction to 0 0 phase reference. Finally, for the phases, the currents are +X directed, hence the current flows in a clockwise and polarization sense is Left Hand in the +Z 24

25 LHCP polarization Clockwise direction 25

26 Radiation Pattern a b Simulated and measured radiation pattern of the LHCP antenna at a) Phi 0 0 b) Phi 90 0 The antenna produces LHCP waves in the Z>0 half spaces, near the +Z direction of which the radiation fields have larger LHCP to RHCP ratios and hence smaller ARs. The measurement agrees quite well with the simulation, especially for LHCP waves in the Z>0 half space. In the measured data for 2.4 GHz, the forward +Z direction LHCP wave at least 36 db larger than the backward - Z direction LHCP wave and 21 db larger than the backward RHCP wave. The HPBW of the proposed antenna achieve near about

27 Parasitic Element Modified RHCP patch antenna with Wide 3dB AR beamwidth 58 mm 80 mm 58 mm Patch feed Ground The optimized value of ground plane size is 58 mm where the minimum axial ratio 0.16 db has achieved. In that case, the refection coefficient and peak gain is dB and 7.05dBic, respectively. By increasing the ground plane sized from its optimized value 58mm, the axial ratio and peak has increased has increased slightly but reflection coefficient remains stable. On the other hand, by decreasing the ground plane sized from its optimized value 58 mm, the axial ratio has increased significantly but peak gain and reflection coefficient has decreased.. The 3 db AR beamwidth is ( to 76 0 CST,) ( to 70 0 HFSS )at ϕ =0 0 plane and (-74 0 to 94 0 CST,) (-72 0 to 82 0 HFSS ) at ϕ =90 0 plane respectively at 2.4 GHz. 27

28 Continued a The reflection coefficient, AR, and peak gain effect of different ground plane size at 2.4 GHz b a b Simulated AR pattern of modified RHCP antenna at 2.4 GHz a) Phi 0 0 b) Phi 90 0 Simulated normalized radiation pattern of the modified RHCP antenna at 2.4 GHz a) Phi 0 0 b) Phi

29 Measured 3D Pattern (a) RHCP (b) LHCP Concerning the antenna radiation pattern, this figure shows the 3D plot of the measured RHCP and LHCP far field pattern at 2.4 GHz. The RHCP figure highlights that the direction of maximum radiation is along to the boresight direction(+z ) with a -3dB aperture of about and RHCP main lobe magnitude of 7.27 dbi. 29

30 Advantages of the prototype over other prototype Characteristics Proposed Antenna Prototype High-Gain Antenna [2] Circular patch antenna [3] Cross Rhombic Antenna [4] Bandwidth GHz-2.46 GHz GHz GHz Overall Size (mm) Weight Material g Rogers 5880 r =2.2, tanδ= g Comparison Titanium With Wideband Antennas Ground r = (radius) 2.80 r =not mentioned g RF60A r =6.15 Comments High Gain Right Hand Circular Polarization Directional radiation pattern High Radiation Efficiency More than 120 degree 3dB Axial Ratio Beamwidth Size and weight comparatively large 3D profile and cannot be easily integrated with satellite body 3D profile and cannot be easily integrated with portable devices Not mentioned 3dB axial ratio beamwidth Size and weight comparatively large High dielectric material has used which are usually inefficient radiators as they allow very little fringing effect Battery Long Life Lower volume than other reported antennas of literature 30

31 Small Satellite Communication Diagram 31

32 Integrating and Testing 32

33 Integrating and Testing 33

34 Summary A novel circularly polarized, high gain, single feed and single layer S band patch antenna for nanosatellite applications has been developed for commercial product. Asymmetric V-shaped slits in the rectangular patch is responsible for the circular polarization (R) which can reduce multipath effects and improve system sensitiveness between transmitting antenna and receiving antenna. By using radiating edges in the asymmetric V-shaped slit patch with probe feed and parasitic strip, the designed antenna achieved desired operating frequency band with the impedance bandwidth of 3.09 % ( GHz) and 3 db axial ratio bandwidth of 0.87% ( GHz) respectively. By adopting truncation of corners and passive rectangular strip in the patch, the designed small satellite antenna can achieve such a stable and wide main lobe in the broadside direction along with high gain inside a compact area. The gain (7.27 dbi) and 3dB axial ratio beamwidth (>120 0 ) of the product will be higher than any other previously reported S band antenna and 34

35 Features High Gain: High gain for long distance communication Polarization: Right Hand Circular Polarization with slotted structure Persistent Radiation Pattern: Directional radiation pattern is exhibited High Radiation Efficiency: 95.89% of the input power is radiated & total antenna loss is less than 5%. 120 degree 3dB Axial Ratio Beamwidth: The bigger axial ratio beamwidth of antenna, the bigger solid angle in which antenna radiates required circular polarization. Battery Long Life: High gain and efficiency ensures low power consumption than other antennas to meet the same features Low volume: Require less space than other high gain antennas previously published. 35

36 Thank You